EP0324817B1 - Gaz electronic switch (pseudo-spark switch) - Google Patents

Gaz electronic switch (pseudo-spark switch) Download PDF

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Publication number
EP0324817B1
EP0324817B1 EP88905787A EP88905787A EP0324817B1 EP 0324817 B1 EP0324817 B1 EP 0324817B1 EP 88905787 A EP88905787 A EP 88905787A EP 88905787 A EP88905787 A EP 88905787A EP 0324817 B1 EP0324817 B1 EP 0324817B1
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Prior art keywords
cathode
anode
electrodes
switch
switch according
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German (de)
French (fr)
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EP0324817A1 (en
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Jens Christiansen
Klaus Frank
Werner Hartmann
Claudius Kozlik
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T2/00—Spark gaps comprising auxiliary triggering means
    • H01T2/02—Spark gaps comprising auxiliary triggering means comprising a trigger electrode or an auxiliary spark gap
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/02—Details
    • H01J17/30—Igniting arrangements

Definitions

  • the invention relates to a gas-electronic switch with a gas discharge chamber in which two metal electrodes, namely a cathode and an anode, are arranged at a distance (d) from one another, the electrodes being separated from one another by an electrically insulating wall of the gas discharge chamber made of ceramic material or glass are separated and the cathode is provided with a hole and the electrodes are connected to the insulating wall by a dense, metal-ceramic connection or fusion and in the gas discharge chamber there is an ionizable low-pressure gas filling under a pressure p such that the product pxd is dimensioned such that the ignition of a gas discharge between the electrodes takes place at a voltage applied to this, which lies in that branch of the characteristic curve of the ignition voltage as a function of the pressure in which the ignition voltage falls with increasing pressure.
  • the invention also relates to a method for operating such a switch.
  • Such a switch is disclosed in DE-A-28 04 393.
  • electrons or ions are generated in a discharge vessel, which is arranged at a distance from one another Has metal electrodes. These metal electrodes are held by an insulating wall surrounding them and have a gas discharge channel which is formed by aligned openings in these electrodes.
  • An ionizable gas filling is introduced into this discharge vessel, which is dimensioned according to the teaching of DE-A-28 04 393 so that the product of the electrode distance (d) and the gas pressure (p) is in the order of 130 pamm (Pascal) mm or less.
  • This pressure range corresponds to the "breakdown of a gas discharge on the left branch of the Paschen curve" in the marking customary for plane-parallel electrodes, the left branch following the minimum in the characteristic curve which describes the breakdown voltage as a function of pxd.
  • pseudo-sparks to mean all gas discharges that ignite spontaneously at pressures that are lower at a given switch than the pressure that describes the minimum in the gas pressure-ignition voltage characteristic curve of the system.
  • plate distance (d) we want to understand the distance between cathode and anode in the vicinity of their hole, which determines the pseudo-spark character of the gas discharge and which must be provided in the cathode and can be provided in the anode.
  • the object of the invention is to provide a pseudo radio switch which has a sufficiently long service life for many switching operations for commercial use and in which there are as few spontaneous, undesirable breakdowns as possible.
  • FIG. 1 shows the basic structure of a discharge vessel with a cathode 11 and an anode 12, which are plate-shaped and arranged parallel to one another at a distance d and are connected to one another in a gas-tight manner by an annular, insulating wall 9.
  • a voltage which is between 5 kV and 50 kV, is applied to the cathode and the anode via connecting terminals 50 and 51. under certain circumstances it can also be below or above what the pseudo-spark gas discharge can take place in the gas discharge channel formed by the holes 5 and 8 with a correspondingly set gas pressure.
  • the gas can be enclosed in a housing which tightly surrounds the arrangement shown.
  • FIG. 1 A realization of the arrangement of electrodes and insulating wall according to the invention is shown in FIG.
  • the gas discharge chamber is located in a cylindrical vessel, the electrically insulating wall 9 of which consists of several sections 9a, 9b, 9c, 9d and 9e.
  • An anode 12, a cathode 11, a screen 15 and two auxiliary electrodes 13 and 14 are located one behind the other in the gas discharge chamber, which are separated from one another by the different sections of the insulating wall 9 and are connected to it in a gas-tight manner.
  • the wall 9 is made of glass or a ceramic material.
  • the anode 12 delimits the discharge chamber at one end.
  • the remaining electrodes are guided radially outwards through the wall 9 between their sections 9a to 9e.
  • a metal cage 2 is provided on the rear of the cathode 11, the cavity 7 of which is connected to the cathode rear space through openings 6 and to the space 1 between the cathode 11 and anode 12 through a hole 5.
  • a metal cage is also provided on the back of the anode 12, the interior 23 of which is connected by a hole 8 to the space 1 between the anode 12 and the cathode 11.
  • a hard metal plate 12c is located on the rear wall of the anode cage; the rear auxiliary electrode 14 is correspondingly made of a hard metal in the central region. The hard metal assembly is intended to make the electrode parts particularly stressed by the impact of charge carriers.
  • the entire system is rotationally symmetrical, with the axis of symmetry 40 also being the axis of the two holes 5 and 8 in the center of the cathode 11 and the anode 12, respectively.
  • the cathode 11 and the anode 12 are flat and consist of a hard metal, while in the outer area 11b or 12b they are made of copper or an alloy with a lower approximation of the thermal expansion coefficient of the wall 9 Thermal expansion coefficients exist as copper, for example from COVAR.
  • the anode and the cathode spring back to form a narrow annular gap 3 and only lead out of the gas discharge chamber at a distance from the front of the electrodes.
  • the electric field is almost perpendicular to the surfaces of the electrodes facing the wall 9 when the voltage is applied to the cathode 11 and anode 12 of the switch.
  • This can be achieved in a narrow space where the annular gap 3 is narrower than the distance d between the anode 11 and cathode 12 in the hole area 1, since the electric field then occurs in a greatly reduced manner when penetrating into the annular gap 3.
  • This ensures that practically no charge carrier acceleration can take place into the annular gap 3, so that the critical area at the contact line 4 between metal, insulator 9a and gas runs practically in the field-free space, and consequently can no longer be an essential starting point for charge carriers.
  • this is important for the suppression of possible sliding discharges, which can otherwise form on the insulator surface when high voltages are present when the switch is stopped and In principle, undesirable breakdowns occur particularly easily at these triple point contact lines 4.
  • the gas discharge occurring during a switching operation is characterized in that a plasma jet runs after the ignition of the switching operation into the space behind the cathode 11 and also undesirably illuminates the wall 9 and transports electrode material into the gas phase by means of a photo effect and sputtering processes, so that dor! Measures are advisable to hinder the diffusion of the electrode material onto the insulator wall 9.
  • Claims 7 and 13 are devoted to this concern. Accordingly, the arrangement shown in FIG. 2 has a screen 15 which screens part of the openings 6 of the cathode cage 2, and the glow discharge electrode 13 located in the cathode rear space is designed in such a way that it is also used for screening of the openings 6 of the cathode cage 2 contributes.
  • the glow discharge electrodes 13 and 14 are provided with ring-shaped extensions 16 and 17 which are parallel to the wall and partially overlap and shield the wall 9.
  • the cathode 11 and the anode 12 are designed in such a way that the pseudo-spark discharge running between them cannot directly illuminate the section 9a of the wall 9.
  • the cathode 11 has an annular extension 18 parallel to the wall 9, which extends into an annular recess 18a of the anode 12.
  • the filling gas is preferably hydrogen and / or deuterium
  • the filling gas is preferably hydrogen and / or deuterium
  • ions of the gas discharge diffuse into the electrodes and into the insulating walls 9a to 9e and because of the metal vapor present has a getter effect.
  • hydrogen and deuterium can be chemically bound by impurities in the electrode material and can also be lost through a relatively high solubility in metals such as copper and nickel. It is therefore advisable to use a hermetically sealed, in particular a melted, gas discharge chamber, in which lost gas can be refilled by measures which are to be influenced from the outside.
  • the hydrogen storage device specified in claim 11 serves this purpose.
  • a hydrogen storage 22 is shown in FIG. 2. It consists of a cylindrical body 22 made of a hydrogen-absorbing metal, e.g. made of titanium, which is e.g. consists of nickel, open at the ends sleeve 21, which is heated by an electrical resistance heater 19.
  • the store 22 is kept at a temperature at which an equilibrium pressure which is suitable for the pseudo-spark discharge is established in the gas filling. In the case of a titanium store, this temperature could be 600 ° C.
  • the memory 22 is arranged in a chamber behind the outer glow discharge electrode 14; the chamber is connected through holes 20 in the glow discharge electrode 14 to the cathode rear space 10, in which the glow discharge takes place.
  • Claims 1 to 15 deal with embodiments of the switch, which are characterized by the use of two main electrodes (cathode 11 and anode 12), each with a hole therein, no further electrodes being arranged between the anode and cathode (cf. FIG. 2 , 3 and 4).
  • switches described in claims 1 to 11 allow high, even in long-term operation Process currents at high switching powers. If a cathode 11 and preferably also an anode 12 with a plurality of holes 5, 24 or 9, 25 are used in such switches, as indicated in claims 16 to 19 and shown in FIG. 4, then one can effectively destroy them Avoid as a consequence of such high currents.
  • the consequence of this measure is, of course, that when the power in switches of this type is increased, possible weaknesses which only occur when the power is high and which would otherwise not be evident become apparent.
  • the next most sensitive area of the switch is that electrode space in which the electron current carrying the switch current is triggered at the cathode 11. It has been shown that the contact of the plasma essentially occurs in hole 5 and that a certain area, depending on the voltage and current of the switching process, is responsible for the essential charge carrier provision. Typical values for this are, for example, areas of electron release on the order of 1 cm2 in the area of hole 5 at current intensities of typically 10 kA. The current density determined in this way is directly correlated with the service life of the electrode surfaces.
  • the pseudo-spark discharge also takes place in the desired sense if not only a hole 5 is made in the cathode 11, but several parallel holes 5, 24 as shown in FIG. 4, the distances between these holes 5, 24 and their diameter should be of the order of magnitude of the electrode spacing (d) in the vicinity of the holes 5, 24 (deviating dimensions, deviating up and down to a factor of 5, are still permissible).
  • the discharge is generally triggered first at one of the holes 5, 24, for example by triggering, which is yet to be described; however, it then automatically spreads to the area of all existing holes 5, 24 during the switching process. In this way, the current load in the areas around the individual holes 5, 24 is greatly reduced because the current is distributed over a larger area.
  • Claims 5, 6, 12, 26 and 27 are concerned with various trigger methods for triggering pseudo spark discharges and the switch designs suitable for this purpose. They all assume the injection of a plasma or the injection of charge carriers from a low-pressure gas discharge (Glow discharge).
  • Glow discharge low-pressure gas discharge
  • two additional electrodes 13 and 14 are provided behind the cathode 11, of which the electrode 13 adjacent to the cathode 11 is the glow discharge electrode, which can be connected positively or negatively, that is to say can serve as the cathode or anode of the grim discharge system.
  • the essential glow discharge current flows from it to the opposite electrode 14, which is essentially at a potential approximately at the level of the potential of the cathode 11 of the switch (or at a potential approximately at the level of the potential of the anode in a further development of the switch according to FIG Claims 13, 14 and 15).
  • the electrode 13 is therefore in such a spatial position that the glow discharge current can branch to the cathode 11 of the switch and to the opposite electrode 14, which is approximately at the same potential as the cathode 11.
  • the current branching is preferably carried out such that only a small part of the glow discharge current flows in the direction of the cathode 11 of the switch, which is then amplified by the measures represented in claims 5, 6 and 12 to 15.
  • a particular advantage of the switch according to the invention is that it can be ignited even if, according to claims 13, 14 and 15, the cathode 11 becomes the anode and the anode 12 the cathode by reversing the polarity. This is not possible with thyratrons.
  • the development of the switch according to claim 25 is particularly suitable for use as a surge arrester.
  • the extinguishing process of the switch 30 (FIG. 5) can be carried out by external, generally passive electrical measures such that a control voltage provided by triggering the switch can be defined for the consumer to be protected against overvoltage.
  • Fig. 5 explains the use of the switch 30 for such an application.
  • the voltage between the connection points 26, 27 is to be reduced by a current bypass if a certain value U of the voltage is exceeded.
  • the regulation stops as soon as this value has been lowered below the voltage U again by the response of the switch. This is achieved, for example, by connecting an RC element 28, 29 between the switch 30 and the consumer (connection points 26 and 27) (the capacitance C (28) being parallel to the switch 30).
  • the switch 30 When the switch 30 is ignited, the capacitor 28 is almost completely discharged. After a short time, the switch 30 extinguishes again if, after the voltage at the deleted switch 30 has risen again, the voltage at the connection points 26, 27 of the consumer to be regulated has not yet been sufficiently lowered. It does not ignite if the voltage has been reduced to the desired extent. Otherwise, the game repeats itself until the voltage drops below the specified value.
  • a triggerable Marx generator can be constructed in such a way that a switch is triggered by the switch chain in a multi-stage Marx generator in the usual way, while the other switches connected in series achieve a breakthrough with high time accuracy by using the method according to claim 26 or 27 .
  • switches By extending the path according to the invention along which a sliding discharge can run along the surface of the insulating wall 9, switches can be constructed which can be operated at very high holding voltages.
  • a technical limit is reached between approximately 50 and 100 kV.
  • the pressure p required for this must be chosen as large as possible, which is necessary for a given holding voltage leads to the electrode gap (d) being as small as possible.
  • the technical limit is then set by the field emission of electrons in the area of the holes 5, 8 and by the fact that with small distances d between the anode 12 and cathode 11 and relatively large holes 5, 8, instabilities and fluctuations therein due to the then extremely steep Ignition voltage characteristic curve occur particularly easily.
  • intermediate electrodes 31 (FIG. 6) and 34 (FIGS. 7 and 8) between cathode 11 and anode 12, as shown in FIGS. 6 to 8, which are either arranged to be free-flowing or connected to voltage dividers outside the gas discharge chamber through which, in the case of three intermediate electrodes, the following potentials are applied to the electrodes, based on the potential of the cathode 11:
  • the dielectric strength is significantly increased by these intermediate electrodes 31 and 34, which expediently run parallel to the cathode 11 and anode 12.
  • the pressure can be at a given distance from cathode 11 and anode 12 the intermediate electrodes 31, 34 are relatively high even at high holding voltages, and the electric field strength becomes relatively small in the individual areas between the electrodes 11, 12, 31, 34.
  • the susceptibility to sliding discharges along the insulating wall 9 is greatly reduced because of the reduction in the field strength. Embodiments of such a switch are the subject of claims 20 and 21.
  • the intermediate electrodes 31 have been installed in the insulating wall 9 as parallel plates between the cathode 11 and the anode 12.
  • the technical teaching given in claim 1 or claim 3 for the anode 12 and the cathode 11 is realized in the intermediate electrodes 34 by the connecting lines 33 between the intermediate electrodes 34, on which metal, gas, are also present in the intermediate electrodes 34 and insulator 9 collide, are protected by a gap 3a against the penetration of the electric field, starting from the respectively opposite electrodes.
  • the intermediate electrodes are designed as hollow disks which only have an annular projection in the middle of their circumference, with which they are held in the insulating wall 9.
  • the intermediate electrodes 31 and 34 have holes 32 and 35, respectively, which are aligned and thereby form a channel in which the pseudo-spark discharge takes place.
  • the cavity in the intermediate electrodes 34 is essentially a field-free space.
  • the switch which is the subject of claim 22 and is shown in FIG. 8, there is a shield plate 36 in the cavity of the intermediate electrodes 34, which interrupts the straight path between the cathode 11 and the anode 12. So that the charge carriers can nevertheless get from the anode to the cathode, the shield plate must of course not completely block the passage through the respective intermediate electrode 34. Therefore, apart from the holes 35, holes 37 are expediently provided in the shield plate 36, through which the charge carriers can reach the anode in a detour. The advantage of this measure is that the dielectric strength is further increased.

Abstract

A switch has a gas discharge chamber in which two electrodes, namely a cathode (11) and an anode (12), are arranged at a distance (d) apart and are separated from each other by an electrically insulating wall (9a) of ceramic material or glass. The cathode (1) has a hole (5) and the electrodes (11, 12) are connected to the insulating wall (9a) through a dense metal-ceramic compound or fused material. The gas discharge chamber contains an ionizing low pressure gas under a pressure p such that ignition of a gas discharge occurs between the electrodes (11, 12) at a voltage on the left, descending branch of the Paschen curve. For at least one of the two electrodes (11, 12), the connecting lines (4) at which the respective electrodes (11, 12), the gas and the wall (9a) meet, are located at a minimal distance from the opposite electrode (12, 11) greater than (d), provided that the corresponding electrode (11, 12) is separated from the wall (9a) by a gap (3) whose width is less than (d).

Description

Die Erfindung betrifft einen gaselektronischen Schalter mit einer Gasentladungskammer, in der zwei Metall-Elektroden, nämlich eine Kathode und eine Anode in einem Abstand (d) voneinander angeordnet sind, wobei die Elektroden durch eine elektrisch isolierende Wand der Gasentladungskammer aus keramischem Material oder aus Glas voneinander getrennt sind und die Kathode mit einem Loch versehen ist und die Elektroden durch eine dichte, metall-keramische Verbindung oder Verschmelzung mit der isolierenden Wand verbunden sind und sich in der Gasentladungskammer eine ionisierbare Niederdruck-Gasfüllung unter einem solchen Druck p befindet, dass das Produkt p x d so bemessen ist, dass die Zündung einer Gasentladung zwischen den Elektroden bei einer an dieser angelegten Spannung erfolgt, welche in jenem Zweig der Kennlinie der Zündspannung in Abhängigkeit vom Druck liegt, in welcher die Zündspannung mit steigendem Druck fällt.The invention relates to a gas-electronic switch with a gas discharge chamber in which two metal electrodes, namely a cathode and an anode, are arranged at a distance (d) from one another, the electrodes being separated from one another by an electrically insulating wall of the gas discharge chamber made of ceramic material or glass are separated and the cathode is provided with a hole and the electrodes are connected to the insulating wall by a dense, metal-ceramic connection or fusion and in the gas discharge chamber there is an ionizable low-pressure gas filling under a pressure p such that the product pxd is dimensioned such that the ignition of a gas discharge between the electrodes takes place at a voltage applied to this, which lies in that branch of the characteristic curve of the ignition voltage as a function of the pressure in which the ignition voltage falls with increasing pressure.

Die Erfindung betrifft auch ein Verfahren zum Betreiben eine derartigen Schalters.The invention also relates to a method for operating such a switch.

Ein solcher Schalter ist in der DE-A-28 04 393 offenbart. In diesem Schalter werden Elektronen bzw. Ionen in einem Entladungsgefäß erzeugt, das im Abstand voneinander angeordnete Metallelektroden aufweist. Diese Metallelektroden sind durch eine sie umgebende Isolierwand gehalten und weisen einen Gasentladungskanal auf, der von fluchtenden Öffnungen in diesen Elektroden gebildet wird. In dieses Entladungsgefäß wird eine ionisierbare Gasfüllung eingebracht, die nach der Lehre der DE-A-28 04 393 so bemessen ist, dass das Produkt aus dem Elektrodenabstand (d) und dem Gasdruck (p) in der Größenanordnung von 130 Pamm (Pascal) mm oder weniger beträgt. Die schnelle funkenähnliche Gasentladung, die sich ergibt, wenn ein solcher Schalter getriggert wird, oder die sich spontan ergibt, sobald die Durchbruchspannung überschritten wird, ist in der Literatur als Pseudofunken-Gasentladung bekannt (D. BLOESS et al: "The triggered speudospark chamber as a fast switch and as a high - intensity beam source" - Nuclear Instruments & Methods in Physics Research, Band 205, Nr. 1/2, Januar 1983, North-Holland Publish Co, Amsterdam NL). Sie tritt in Erweiterung des in der DE-A-28 04 393 festgelegten p x d-Bereiches bei Werten von p x d auf, die eine fallende Zündspannungs-Druckcharakteristik bei steigendem Druck aufweisen. Dieser Druckbereich entspricht in der für planparallele Elektroden üblichen Kennzeichnung dem "Durchbruch einer Gasentladung am linken Ast der Paschen-Kurve", wobei der linke Ast anschließt an das Minimum in der Kennlinie, die die Durchbruchspannung als Funktion von p x d beschreibt. Im Rahmen dieser Patentschrift wollen wir unter Pseudofunken alle Gasentladungen verstehen, die bei Drücken spontan zünden, die bei einem gegebenen Schalter kleiner sind als jener Druck, der das Minimum in der Gasdruck-Zündspannung-Kennlinie des Systems beschreibt. Als Plattenabstand (d) wollen wir den Abstand zwischen Kathode und Anode in der Nähe ihres Loches verstehen, das den Pseudofunken-Charakter der Gasentladung bestimmt und das in der Kathode vorgesehen sein muss und in der Anode vorgesehen sein kann.Such a switch is disclosed in DE-A-28 04 393. In this switch, electrons or ions are generated in a discharge vessel, which is arranged at a distance from one another Has metal electrodes. These metal electrodes are held by an insulating wall surrounding them and have a gas discharge channel which is formed by aligned openings in these electrodes. An ionizable gas filling is introduced into this discharge vessel, which is dimensioned according to the teaching of DE-A-28 04 393 so that the product of the electrode distance (d) and the gas pressure (p) is in the order of 130 pamm (Pascal) mm or less. The rapid spark-like gas discharge that occurs when such a switch is triggered, or that occurs spontaneously as soon as the breakdown voltage is exceeded, is known in the literature as pseudo-spark gas discharge (D. BLOESS et al: "The triggered speudospark chamber as a fast switch and as a high-intensity beam source "- Nuclear Instruments & Methods in Physics Research, Volume 205, No. 1/2, January 1983, North-Holland Publish Co, Amsterdam NL). It occurs as an extension of the px d range specified in DE-A-28 04 393 at values of pxd which have a falling ignition voltage / pressure characteristic with increasing pressure. This pressure range corresponds to the "breakdown of a gas discharge on the left branch of the Paschen curve" in the marking customary for plane-parallel electrodes, the left branch following the minimum in the characteristic curve which describes the breakdown voltage as a function of pxd. For the purposes of this patent, we mean pseudo-sparks to mean all gas discharges that ignite spontaneously at pressures that are lower at a given switch than the pressure that describes the minimum in the gas pressure-ignition voltage characteristic curve of the system. As plate distance (d) we want to understand the distance between cathode and anode in the vicinity of their hole, which determines the pseudo-spark character of the gas discharge and which must be provided in the cathode and can be provided in the anode.

In der Literatur existieren zahlreiche Abhandlungen über Eigenschaften und Betrieb von Pseudofunkenkammern und Pseudofunkenschaltern, -siche auch D.BLOESS, a.a.O.. Im allgemeinen ist ihre isolierende Wand so angebracht, dass sie senkrecht auf den Elektroden steht (Fig. 1) und ihre Länge gleich dem Elektrodenabstand ist. Die veröffentlichten Untersuchungen sind bisher fast ausschließlich für wissenschaftliche Zwecke durchgeführt worden, so dass die Lebensdauer und die Existenz eines dauernd mit Gas gefüllten Schalters nicht von Bedeutung war.There are numerous treatises in the literature on the properties and operation of pseudo-spark chambers and pseudo-spark switches, including D.BLOESS, loc.cit. In general, their insulating wall is mounted so that it is perpendicular to the electrodes (Fig. 1) and its length is the same Is the electrode gap. The published investigations have so far been carried out almost exclusively for scientific purposes, so that the service life and the existence of a switch that is constantly filled with gas were not important.

Aufgabe der Erfindung ist es, einen Pseudofunkenschalter zu schaffen, der eine für die gewerbliche Anwendung hinreichend lange Lebensdauer bei vielen Schaltvorgängen aufweist und bei dem möglichst keine spontanen, unerwünschten Durchschläge auftreten.The object of the invention is to provide a pseudo radio switch which has a sufficiently long service life for many switching operations for commercial use and in which there are as few spontaneous, undesirable breakdowns as possible.

Diese Aufgabe wird gelöst durch einen Schalter mit den im Anspruch 1 angegebenen Merkmalen. Vorteilhafte Weiterbildungen der Erfindung sind Gegenstand der Unteransprüche.This object is achieved by a switch with the features specified in claim 1. Advantageous developments of the invention are the subject of the dependent claims.

Für die isolierende Wand des erfindungsgemäßen Schalters wird Glas oder ein keramischer Werkstoff verwendet und mit den Elektroden so verbunden, dass keine nennenswerte Gasabgabe an das System beim Betrieb des Schalters erfolgen kann. Die Erfindung stellt sicher, dass Metalldampf, der seinen Ursprung im wesentlichen an den Elektroden in der Nähe der Löcher in der Kathode und ggfs. in der Anode hat, an seiner Diffusion zur Isolatorwand und am Niederschlagen auf ihr gehindert wird. Dieser Diffusionsbehinderung dienen insbesondere die im Patentanspruch 9 aufgeführten Schirme. Trotz solcher Schirme könnte bei Langzeitbetrieb des Schalters noch diffundierender Metalldampf sich an den Isolatoren niederschlagen und zu einer leitenden Brücke führen, wenn dem nicht die im Patentanspruch 1 angegebene Erfindung begegnete, indem sie dafür sorgt, dass der Niederschlagsbereich, der im wesentlichen in der Verlängerung des Diffusionsweges auftritt, unterbrochen wird durch eine geschützte Zone der isolierenden Wand zwischen Kathode und Anode. Dieses wird erreicht, indem die Elektrodenform so ausgebildet wird, dass die Berührungslinien zwischen den Elektroden und dem Isolator hinter engen schlitzartigen Vertiefungen so versteckt werden, dass das elektrische Feld nur noch geringfügig durch diese Schlitze hindurchgreifen kann. Dadurch wird dort die Anfachung einer Entladung selbst bei geringfügiger Bedampfung der Isolatorwand weitgehend unterdrückt.

  • Figur 1 zeigt schematisch die Grundelemente einer Gasentladungskammer für eine Pseudofunken-Gasentladung, wie sie sich aus dem Stand der Technik ergibt,
  • Figur 2 zeigt schematisch eine erfindungsgemäße Gasentladungskammer mit den zugehörigen Elektroden,
  • Figur 3 zeigt ein zweites Ausführungsbeispiel einer Gasentladungskammer im Längsschnitt mit einer gegenüber dem in Fig. 2 dargestellten Beispiel abgewandelten Elektrodenanordnung,
  • Figur 4 zeigt für eine Gasentladungskammer, wie sie in Fig. 2 dargestellt ist, eine abgewandelte Ausbildung von Anode und Kathode, jeweils mit mehreren Löchern,
  • Figur 5 ist ein Schaltbild, welches den Einsatz eines erfindungsgemäßen Schalters zur Ableitung von Überspannungen aus einem elektrischen Netzwerk zeigt,
  • Figur 6 zeigt eine Abwandlung des in Fig. 2 dargestellten Ausführungsbeispieles mit Hilfselektroden zwischen Kathode und Anode,
  • Figur 7 zeigt eine Abwandlung der in Fig. 6 dargestellten Elektrodenanordnung, in welcher die zwischen Kathode und Anode vorgesehenen Hilfselektroden hohl ausgebildet sind,
  • Figur 8 zeigt eine Abwandlung der in Fig. 7 dargestellten Elektrodenanordnung, in welcher im Hohlraum der Hilfselektroden ein Abschirmblech angeordnet ist, und
  • Figur 9 zeigt schematisch die Anordnung mehrerer erfindungsgemäßer Schalter, die gemeinsam parallel mit dem Gas versorgt werden, in welchem die Gasentladung stattfindet.
Glass or a ceramic material is used for the insulating wall of the switch according to the invention and is connected to the electrodes in such a way that no significant gas can be released to the system when the switch is in operation. The invention ensures that metal vapor that originates essentially on the electrodes near the holes in the cathode and possibly in the anode, is prevented from diffusing to the insulator wall and from being deposited on it. This diffusion hindrance serves in particular the screens listed in claim 9. Despite such screens, diffusing metal vapor could deposit on the insulators during long-term operation of the switch and lead to a conductive bridge if this was not met by the invention specified in claim 1 by ensuring that the precipitation area, which essentially extends the Diffusion path occurs, is interrupted by a protected zone of the insulating wall between the cathode and anode. This is achieved by designing the electrode shape in such a way that the lines of contact between the electrodes and the insulator are hidden behind narrow slot-like depressions in such a way that the electric field can only reach through these slots to a slight extent. As a result, the build-up of a discharge is largely suppressed there, even with slight vapor deposition on the insulator wall.
  • FIG. 1 schematically shows the basic elements of a gas discharge chamber for a pseudo-spark gas discharge, as it results from the prior art,
  • FIG. 2 schematically shows a gas discharge chamber according to the invention with the associated electrodes,
  • FIG. 3 shows a second exemplary embodiment of a gas discharge chamber in longitudinal section with an electrode arrangement modified compared to the example shown in FIG. 2,
  • FIG. 4 shows a modified design of anode and cathode, each with several holes, for a gas discharge chamber as shown in FIG. 2,
  • FIG. 5 is a circuit diagram which shows the use of a switch according to the invention for deriving overvoltages from an electrical network,
  • FIG. 6 shows a modification of the exemplary embodiment shown in FIG. 2 with auxiliary electrodes between cathode and anode,
  • FIG. 7 shows a modification of the electrode arrangement shown in FIG. 6, in which the auxiliary electrodes provided between the cathode and the anode are hollow.
  • FIG. 8 shows a modification of the electrode arrangement shown in FIG. 7, in which a shielding plate is arranged in the cavity of the auxiliary electrodes, and
  • FIG. 9 schematically shows the arrangement of a plurality of switches according to the invention, which are jointly supplied in parallel with the gas in which the gas discharge takes place.

Wege zur Ausführung der Erfindung:WAYS OF CARRYING OUT THE INVENTION:

In den verschiedenen Ausführungsbeispielen sind gleiche oder einander entsprechende Teile mit übereinstimmenden Bezugszahlen bezeichnet.In the various exemplary embodiments, identical or corresponding parts are identified by corresponding reference numbers.

Figur 1 zeigt den Grundaufbau eines Entladungsgefäßes mit einer Kathode 11 und einer Anode 12, welche plattenförmig ausgebildet sind und parallel zueinander im Abstand d angeordnet und durch eine ringförmige, isolierende Wand 9 gasdicht miteinander verbunden sind. In der Mitte der Kathode 11 befindet sich ein Loch 5, und diesem gegenüberliegend befindet sich in der Anode 12 ein weiteres Loch 8. Über Anschlußklemmen 50 und 51 wird an die Kathode und die Anode eine Spannung angelegt, die zwischen 5 kV und 50 kV, unter Umständen auch darunter oder darüber liegen kann, womit in dem durch die Löcher 5 und 8 gebildeten Gasentladungskanal bei entsprechend eingestelltem Gasdruck die Pseudofunken-Gasentladung stattfinden kann. Das Gas kann in einem die dargestellte Anordnung dicht umgebenden Gehäuse eingeschlossen sein.FIG. 1 shows the basic structure of a discharge vessel with a cathode 11 and an anode 12, which are plate-shaped and arranged parallel to one another at a distance d and are connected to one another in a gas-tight manner by an annular, insulating wall 9. There is a hole 5 in the middle of the cathode 11, and a hole 8 is located opposite this in the anode 12. A voltage which is between 5 kV and 50 kV, is applied to the cathode and the anode via connecting terminals 50 and 51. under certain circumstances it can also be below or above what the pseudo-spark gas discharge can take place in the gas discharge channel formed by the holes 5 and 8 with a correspondingly set gas pressure. The gas can be enclosed in a housing which tightly surrounds the arrangement shown.

In Figur 2 wird eine Realisierung der erfindungsgemäßen Anordnung von Elektroden und isolierender Wand gezeigt. Die Gasentladungskammer befindet sich in einem zylindrischen Gefäß, dessen elektrisch isolierende Wand 9 hintereinander aus mehreren Abschnitten 9a, 9b, 9c, 9d und 9e besteht. In der Gasentladungskammer befinden sich hintereinander eine Anode 12, eine Kathode 11, ein Schirm 15 und zwei Hilfselektroden 13 und 14, welche durch die verschiedenen Abschnitte der isolierenden Wand 9 voneinander getrennt und gasdicht mit ihr verbunden sind. Die Wand 9 besteht aus Glas oder einem keramischen Werkstoff. Die Anode 12 begrenzt die Entladungskammer am einen Ende. Die übrigen Elektroden sind durch die Wand 9 zwischen ihren Abschnitten 9a bis 9e radial nach aussen geführt.A realization of the arrangement of electrodes and insulating wall according to the invention is shown in FIG. The gas discharge chamber is located in a cylindrical vessel, the electrically insulating wall 9 of which consists of several sections 9a, 9b, 9c, 9d and 9e. An anode 12, a cathode 11, a screen 15 and two auxiliary electrodes 13 and 14 are located one behind the other in the gas discharge chamber, which are separated from one another by the different sections of the insulating wall 9 and are connected to it in a gas-tight manner. The wall 9 is made of glass or a ceramic material. The anode 12 delimits the discharge chamber at one end. The remaining electrodes are guided radially outwards through the wall 9 between their sections 9a to 9e.

Auf der Rückseite der Kathode 11 ist ein Metallkäfig 2 vorgesehen, dessen Hohlraum 7 durch Öffnungen 6 mit dem Kathoden-Hinterraum und durch ein Loch 5 mit dem Raum 1 zwischen Kathode 11 und Anode 12 in Verbindung steht. Auf der Rückseite der Anode 12 ist ebenfalls ein Metallkäfig vorgesehen, dessen Innenraum 23 durch ein Loch 8 mit dem Raum 1 zwischen Anode 12 und Kathode 11 verbunden ist. Auf der Rückwand des Anodenkäfigs befindet sich eine Hartmetallplatte 12c; entsprechend ist die hintere Hilfselektrode 14 im Mittelbereich aus einem Hartmetall. Die Hartmetallbestückung soll die durch das Auftreffen von Ladungsträgern besonders beanspruchten Elektrodenteile widerstandsfähig machen.A metal cage 2 is provided on the rear of the cathode 11, the cavity 7 of which is connected to the cathode rear space through openings 6 and to the space 1 between the cathode 11 and anode 12 through a hole 5. A metal cage is also provided on the back of the anode 12, the interior 23 of which is connected by a hole 8 to the space 1 between the anode 12 and the cathode 11. A hard metal plate 12c is located on the rear wall of the anode cage; the rear auxiliary electrode 14 is correspondingly made of a hard metal in the central region. The hard metal assembly is intended to make the electrode parts particularly stressed by the impact of charge carriers.

Das ganze System ist rotationssymmetrisch, wobei die Symmetrieachse 40 zugleich die Achse der zwei Löcher 5 und 8 in der Mitte der Kathode 11 bzw. der Anode 12 ist. Im Umgebungsbereich 11a bzw. 12a der Löcher 5 und 8 sind die Kathode 11 und die Anode 12 eben ausgebildet und bestehen aus einem Hartmetall während sie im Aussenbereich 11b bzw. 12b aus Kupfer oder aus einer Legierung mit niedrigerem, an den Wärmeausdehnungskoeffizienten der Wand 9 angenäherten Wärmeausdehnungskoeffizienten als Kupfer bestehen, z.B. aus COVAR. Nahe beim Abschnitt 9a der Wand 9 springen jedoch die Anode und die Kathode unter Bildung eines engen Ringspalts 3 zurück und führen erst in einigem Abstand von der Vorderseite der Elektroden aus der Gasentladungskammer heraus. Im Ringspalt 3 steht das elektrische Feld bei anliegender Spannung an Kathode 11 und Anode 12 des Schalters fast senkrecht auf den der Wand 9 zugewandten Oberflächen der Elektroden. Dies läßt sich bei einem engen Raumgebiet, wo der Ringspalt 3 schmaler ist als der Abstand d zwischen Anode 11 und Kathode 12 im Lochbereich 1 erreichen, da dann das elektrische Feld beim Eindringen in den Ringspalt 3 sehr stark reduziert auftritt. Auf diese Weise ist gewährleistet, dass in den Ringspalt 3 hinein praktisch keine Ladungsträgerbeschleunigung erfolgen kann, so dass der kritische Bereich an der Berührungslinie 4 zwischen Metall, Isolator 9a und Gas praktisch im feldfreien Raum verläuft, mithin nicht mehr wesentlicher Ausgangspunkt von Ladungsträgern sein kann. Dies ist gleichzeitig wichtig für die Unterdrückung möglicher Gleitentladungen, die bei Anliegen hoher Spannungen im Haltezustand des Schalters sich sonst auf der Isolator-Oberfläche ausbilden können und die als unerwünschte Durchschläge prinzipiell besonders leicht an diesen tripelpunktartigen Berührungslinien 4 entstehen.The entire system is rotationally symmetrical, with the axis of symmetry 40 also being the axis of the two holes 5 and 8 in the center of the cathode 11 and the anode 12, respectively. In the surrounding area 11a or 12a of the holes 5 and 8, the cathode 11 and the anode 12 are flat and consist of a hard metal, while in the outer area 11b or 12b they are made of copper or an alloy with a lower approximation of the thermal expansion coefficient of the wall 9 Thermal expansion coefficients exist as copper, for example from COVAR. However, near the section 9a of the wall 9, the anode and the cathode spring back to form a narrow annular gap 3 and only lead out of the gas discharge chamber at a distance from the front of the electrodes. In the annular gap 3, the electric field is almost perpendicular to the surfaces of the electrodes facing the wall 9 when the voltage is applied to the cathode 11 and anode 12 of the switch. This can be achieved in a narrow space where the annular gap 3 is narrower than the distance d between the anode 11 and cathode 12 in the hole area 1, since the electric field then occurs in a greatly reduced manner when penetrating into the annular gap 3. This ensures that practically no charge carrier acceleration can take place into the annular gap 3, so that the critical area at the contact line 4 between metal, insulator 9a and gas runs practically in the field-free space, and consequently can no longer be an essential starting point for charge carriers. At the same time, this is important for the suppression of possible sliding discharges, which can otherwise form on the insulator surface when high voltages are present when the switch is stopped and In principle, undesirable breakdowns occur particularly easily at these triple point contact lines 4.

Diese wichtige Maßnahme für die Langzeitstabilität von Pseudofunkenschaltern, insbesondere von Hochstromschaltern, wird am besten wirksam, wenn zwischen beiden Hauptelektroden (Kathode 11 und Anode 12) des Schalters und der isolierenden Wand 9a ein solcher enger Spalt 3 vorgesehen ist, so dass de facto die Elektrodendurchführungen durch die Wand 9 im Vergleich zu planparallelen Elektroden (Fig. 1) geometrisch zurückgesetzt sind. Ein wesentlicher Effekt im Sinne der Erfindung wird aber schon dadurch erreicht, dass nur bei einer der beiden Elektroden 11 oder 12 die Elektrodendurchführung zurückgesetzt wird, wie es der Patentanspruch 1 fordert.This important measure for the long-term stability of pseudo-radio switches, in particular high-current switches, is best effective if such a narrow gap 3 is provided between the two main electrodes (cathode 11 and anode 12) of the switch and the insulating wall 9a, so that the electrode bushings are de facto are geometrically reset by the wall 9 in comparison to plane-parallel electrodes (FIG. 1). An essential effect in the sense of the invention is achieved, however, by only resetting the electrode feedthrough in one of the two electrodes 11 or 12, as claimed in claim 1.

Die bei einem Schaltvorgang ablaufende Gasentladung ist dadurch gekennzeichnet, dass ein Plasmastrahl nach dem Zünden des Schaltvorgangs in den hinter der Kathode 11 liegenden Raum läuft und auch dort unerwünschterweise die Wand 9 beleuchtet und durch Photoeffekt und durch Sputterprozesse Elektrodenmaterial in die Gasphase transportiert, so dass auch dor! Maßnahmen ratsam sind, um die Diffusion des Elektrodenmaterials an die Isolatorwand 9 zu behindern. Diesem Anliegen sind die Ansprüche 7 und 13 gewidmet. Demgemäß hat die in Fig. 2 dargestellte Anordnung einen Schirm 15, welcher einen Teil der Öffnungen 6 des Kathodenkäfigs 2 abschirmt, und die im Kathodenhinterraum liegende Glimmentladungselektrode 13 ist so gestaltet, dass sie ebenfalls zur Abschirmung der Öffnungen 6 des Kathodenkäfigs 2 beitragt. Im Ausführungsbeispiel gemäß Fig. 3 sind die Glimmentladungselektroden 13 und 14 mit zur Wand parallelen, sich teilweise überlappenden, ringförmigen Fortsätzen 16 und 17 versehen, die die Wand 9 abschirmen.The gas discharge occurring during a switching operation is characterized in that a plasma jet runs after the ignition of the switching operation into the space behind the cathode 11 and also undesirably illuminates the wall 9 and transports electrode material into the gas phase by means of a photo effect and sputtering processes, so that dor! Measures are advisable to hinder the diffusion of the electrode material onto the insulator wall 9. Claims 7 and 13 are devoted to this concern. Accordingly, the arrangement shown in FIG. 2 has a screen 15 which screens part of the openings 6 of the cathode cage 2, and the glow discharge electrode 13 located in the cathode rear space is designed in such a way that it is also used for screening of the openings 6 of the cathode cage 2 contributes. In the exemplary embodiment according to FIG. 3, the glow discharge electrodes 13 and 14 are provided with ring-shaped extensions 16 and 17 which are parallel to the wall and partially overlap and shield the wall 9.

In ähnlicher Weise sind bei dem in Fig. 3 dargestellten Ausführungsbeispiel die Kathode 11 und die Anode 12 so gestaltet, dass die zwischen ihnen ablaufende Pseudofunkenentladung den Abschnitt 9a der Wand 9 nicht direkt beleuchten kann. Zu diesem Zweck hat die Kathode 11 einen zur Wand 9 parallelen ringförmigen Fortsatz 18, der in eine ringförmige Ausnehmung 18a der Anode 12 eintaucht.Similarly, in the exemplary embodiment shown in FIG. 3, the cathode 11 and the anode 12 are designed in such a way that the pseudo-spark discharge running between them cannot directly illuminate the section 9a of the wall 9. For this purpose, the cathode 11 has an annular extension 18 parallel to the wall 9, which extends into an annular recess 18a of the anode 12.

Die Wechselwirkung des Plasmas mit den Wänden der Gasentladungskammer bewirkt insbesondere bei Hochstrombelastung eine allmähliche Verringerung des Gasdrucks (das Füllgas ist vorzugsweise Wasserstoff und/oder Deuterium) weil Ionen der Gasentladung in die Elektroden und in die isolierenden Wände 9a bis 9e diffundieren und weil der vorhandene Metalldampf eine Getterwirkung ausübt. Ausserdem können Wasserstoff und Deuterium durch Verunreinigungen im Elektrodenwerkstoff chemisch gebunden werden und auch durch eine verhältnismässig hohe Löslichkeit in Metallen wie Kupfer und Nickel verlorengehen. Es ist daher sinnvoll, eine hermetisch dichte, insbesondere eine abgeschmolzene Gasentladungskammer zu verwenden, in der eine Nachfüllung von verlorengegangenem Gas durch Maßnahmen erfolgen kann, die von aussen zu beeinflussen sind.The interaction of the plasma with the walls of the gas discharge chamber brings about a gradual reduction in the gas pressure, especially under high current loads (the filling gas is preferably hydrogen and / or deuterium) because ions of the gas discharge diffuse into the electrodes and into the insulating walls 9a to 9e and because of the metal vapor present has a getter effect. In addition, hydrogen and deuterium can be chemically bound by impurities in the electrode material and can also be lost through a relatively high solubility in metals such as copper and nickel. It is therefore advisable to use a hermetically sealed, in particular a melted, gas discharge chamber, in which lost gas can be refilled by measures which are to be influenced from the outside.

Hierzu dient der im Anspruch 11 aufgeführte Wasserstoffspeicher. In Fig. 2 ist ein solcher Wasserstoffspeicher 22 dargestellt. Er besteht aus einem zylindrischen Körper 22 aus einem Wasserstoff aufnehmenden Metall, z.B. aus Titan, welches in einer z.B. aus Nickel bestehenden, an den Enden offene Hülse 21 besteht, die durch eine elektrische Widerstandsheizung 19 beheizt wird. Der Speicher 22 wird auf einer Temperatur gehalten, bei welcher sich ein für die Pseudofunkenentladung geeigneter Gleichgewichtsdruck in der Gasfüllung einstellt. Im Falle eines Titanspeichers könnte diese Temperatur bei 600°C liegen. Der Speicher 22 ist in einer Kammer hinter der äußeren Glimmentladungselektrode 14 angeordnet; die Kammer ist durch Löcher 20 in der Glimmentladungselektrode 14 mit dem Kathoden-Hinterraum 10 verbunden, in welchem die Glimmentladung stattfindet.The hydrogen storage device specified in claim 11 serves this purpose. Such a hydrogen storage 22 is shown in FIG. 2. It consists of a cylindrical body 22 made of a hydrogen-absorbing metal, e.g. made of titanium, which is e.g. consists of nickel, open at the ends sleeve 21, which is heated by an electrical resistance heater 19. The store 22 is kept at a temperature at which an equilibrium pressure which is suitable for the pseudo-spark discharge is established in the gas filling. In the case of a titanium store, this temperature could be 600 ° C. The memory 22 is arranged in a chamber behind the outer glow discharge electrode 14; the chamber is connected through holes 20 in the glow discharge electrode 14 to the cathode rear space 10, in which the glow discharge takes place.

Die Ansprüche 1 bis 15 befassen sich mit Ausführungsformen des Schalters, welche durch die Verwendung von zwei Hauptelektroden (Kathode 11 und Anode 12) mit jeweils einem Loch darin gekennzeichnet sind, wobei zwischen Anode und Kathode keine weiteren Elektroden angeordnet sind (vgl. Fig. 2, 3 und 4).Claims 1 to 15 deal with embodiments of the switch, which are characterized by the use of two main electrodes (cathode 11 and anode 12), each with a hole therein, no further electrodes being arranged between the anode and cathode (cf. FIG. 2 , 3 and 4).

Die in den Ansprüchen 1 bis 11 beschriebenen Ausführungsformen von Schaltern erlauben es, auch im Langzeitbetrieb hohe Ströme bei hohen Schaltleistungen zu verarbeiten. Verwendet man in solchen Schaltern eine Kathode 11 und vorzugsweise auch eine Anode 12 mit mehreren Löchern 5, 24 bzw. 9, 25, wie in den Ansprüchen 16 bis 19 angegeben und in Fig. 4 dargestellt, dann kann man dadurch wirksam Zerstörungen, die eine Folge von so hohen Strömen sein könnten, optimal vermeiden. Die Folge dieser Maßnahme ist natürlich, dass bei Steigerung der Leistung in derartigen Schaltern nur bei großen Leistungen auftretende mögliche Schwachstellen erkennbar werden, die sonst nicht zum Tragen kämen.The embodiments of switches described in claims 1 to 11 allow high, even in long-term operation Process currents at high switching powers. If a cathode 11 and preferably also an anode 12 with a plurality of holes 5, 24 or 9, 25 are used in such switches, as indicated in claims 16 to 19 and shown in FIG. 4, then one can effectively destroy them Avoid as a consequence of such high currents. The consequence of this measure is, of course, that when the power in switches of this type is increased, possible weaknesses which only occur when the power is high and which would otherwise not be evident become apparent.

Bei Hochleistungsschaltern, bei denen die Isolatoren auf die erfindungsgmäße Weise geschützt sind, ist der nächstanfällige Bereich des Schalters jener Elektrodenraum ist, in dem der den Schalterstrom tragende Elektronenstrom an der Kathode 11 ausgelöst wird. Es hat sich gezeigt, dass die Berührung des Plasmas im wesentlichen im Loch 5 auftritt und dass eine gewisse Fläche, je nach Spannung und Strom des Schaltvorganges, für die wesentliche Ladungsträgerbereitstellung verantwortlich ist. Typische Werte dazu sind z.B. Flächen der Elektronenauslösung in der Größenordnung von 1 cm² im Bereich des Loches 5 bei Stromstärken von typischerweise 10 kA. Die dadurch bestimmte Stromdichte ist direkt korreliert mit der Lebensdauer der Elektrodenoberflächen. Gemäß einer Weiterbildung der Erfindung ist deshalb zur Verlängerung der Stabilität der Elektroden und damit zur Erhöhung der Lebensdauer der Schalter vorgesehen, ein geeignetes Elektrodenmaterial zu wählen, wie es im Anspruch 8 angegeben ist, sowie Maßnahmen zu ergreifen, um die stromtragende Fläche des Schaltvorgangs zu erweitern. Dazu hat es sich gezeigt, dass die Pseudofunkenentladung auch dann im gewünschten Sinne stattfindet, wenn nicht nur ein Loch 5 in der Kathode 11 angebracht ist, sondern mehrere parallele Löcher 5, 24 wie in Fig. 4 dargestellt, wobei die Abstände dieser Löcher 5, 24 und ihre Durchmesser von der Größenordnung des Elektrodenabstandes (d) in der Nähe der Löcher 5, 24 sein sollten (abweichende Maße, nach oben und unten abweichend bis zum Faktor 5, sind noch zulässig). In diesem Fall wird die Entladung im allgemeinen zunächst an einem der Löcher 5, 24 ausgelöst, z.B. durch eine noch zu beschreibende Triggerung; sie breitet sich dann jedoch während des Schaltvorgangs selbständig auf den Bereich sämtlicher vorhandener Löcher 5, 24 aus. Auf diese Weise ist die Strombelastung in den Bereichen um die einzelnen Löcher 5, 24 herum stark reduziert, weil sich der Strom auf eine größere Fläche verteilt.In the case of high-power switches in which the insulators are protected in the manner according to the invention, the next most sensitive area of the switch is that electrode space in which the electron current carrying the switch current is triggered at the cathode 11. It has been shown that the contact of the plasma essentially occurs in hole 5 and that a certain area, depending on the voltage and current of the switching process, is responsible for the essential charge carrier provision. Typical values for this are, for example, areas of electron release on the order of 1 cm² in the area of hole 5 at current intensities of typically 10 kA. The current density determined in this way is directly correlated with the service life of the electrode surfaces. According to a development of the invention, therefore, to extend the stability of the electrodes and thus to increase the service life of the switches, it is provided to choose a suitable electrode material, as specified in claim 8, and to take measures to expand the current-carrying area of the switching process . For this purpose, it has been shown that the pseudo-spark discharge also takes place in the desired sense if not only a hole 5 is made in the cathode 11, but several parallel holes 5, 24 as shown in FIG. 4, the distances between these holes 5, 24 and their diameter should be of the order of magnitude of the electrode spacing (d) in the vicinity of the holes 5, 24 (deviating dimensions, deviating up and down to a factor of 5, are still permissible). In this case, the discharge is generally triggered first at one of the holes 5, 24, for example by triggering, which is yet to be described; however, it then automatically spreads to the area of all existing holes 5, 24 during the switching process. In this way, the current load in the areas around the individual holes 5, 24 is greatly reduced because the current is distributed over a larger area.

Die Ansprüche 5, 6, 12, 26 und 27 befassen sich mit verschiedenen Triggerverfahren zur Auslösung von Pseudofunkenentladungen und den dazu geeigneten Ausbildungen des Schalters. Sie gehen alle von der Injektion eines Plasmas bzw. von der Injektion von Ladungsträgern aus einer Niederdurck-Gasentladung (Glimmentladung) aus. Entsprechend Fig. 2 sind dazu hinter der kathode 11 zwei zusätzliche Elektroden 13 und 14 vorgesehen, von denen die der Kathode 11 benachbarte Elektrode 13 die Glimmentladungselektrode ist, die positiv oder negativ geschaltet sein, also als Kathode oder Anode des Grimmentladungssystems dienen kann. Von ihr fließt der wesentliche Glimmentladungsstrom zur gegenüberliegenden Elektrode 14, die sich im wesentlichen auf einem Potential in etwa auf der Höhe des Potentials der Kathode 11 des Schalters befindet (bzw. auf einer Potential ungefähr in Höhe des Potentials der Anode bei einer Weiterbildung des Schalters gemäß Anspruch 13, 14 und 15). Die Elektrode 13 ist also in einer solchen räumlichen Position, dass der Glimmentladungsstrom sich zur Kathode 11 des Schalters und zur gegenüberliegenden Elektrode 14, die sich ungefähr auf gleichen Potential wie die Kathode 11 befindet, verzweigen kann. Vorzugsweise wird die Stromverzweigung so vorgenommen, dass nur ein kleiner Teil des Glimmentladungsstroms in Richtung Kathode 11 des Schalters fließt, der dann durch die in den Ansprüchen 5, 6 und 12 bis 15 dargestellten Maßnahmen verstärkt wird. Um einen fluktuationsfreien Ablauf des Schaltvorgangs zu erreichen, ist es ratsam die Stromverzweigung so einzustellen, dass ein nennenswerter Dauerstrom in den Bereich des Lochs 5 der Kathode 11 gelangt. (Typische Werte für diesen Dauerstrom, die bei einer realen Anordnung gewählt werden können, liegen zwischen 10⁻⁷A und 10⁻⁵A). Dieser Ladungsträgerstrom, der in das Loch 5 der Kathode 11 des Schalters gelangt, bewirkt,dass hier ständig ein schwaches Untergrund-Plasma vorhanden ist. Dieses hat zur Folge, dass die stochastischen Fluktuationen beim Auslösen des Schaltvorgangs gering sind. Es muss gewissermaßen nicht auf das Elektron zum Auslösen der Pseudofunkenentladung gewartet werden, so dass die stochastisch stark fluktuierende Wartestatistik nicht zum Zuge kommt, wohl aber kleinere statistische Schwankungen auftreten, die abhängig sind von der Mächtigkeit des kontinuierlich vorhandenen Plasmas im Kathodenlochbereich. Das ständige Vorhandensein eines solchen Ladungsträgerstrom hat zur Folge, dass die Stärke des durch einen Triggervorgang zusätzlich injizierten Plasmas bzw. die Stärke eines durch gezielte photoelektrische Wechselwirkung durch Beleuchtung des Raums 7 hinter der Kathode 11 zusätzlich ausgelösten Plasmas gering gehalten werden kann. Analogerweise wird durch einen solchen ständigen Ladungsträgerstrom die Präzision des Auslösens des Schaltvorgangs bei Erreichen einer Überspannung im Falle der Ansprüche 25 bis 27 wesentlich verbessert.Claims 5, 6, 12, 26 and 27 are concerned with various trigger methods for triggering pseudo spark discharges and the switch designs suitable for this purpose. They all assume the injection of a plasma or the injection of charge carriers from a low-pressure gas discharge (Glow discharge). According to FIG. 2, two additional electrodes 13 and 14 are provided behind the cathode 11, of which the electrode 13 adjacent to the cathode 11 is the glow discharge electrode, which can be connected positively or negatively, that is to say can serve as the cathode or anode of the grim discharge system. The essential glow discharge current flows from it to the opposite electrode 14, which is essentially at a potential approximately at the level of the potential of the cathode 11 of the switch (or at a potential approximately at the level of the potential of the anode in a further development of the switch according to FIG Claims 13, 14 and 15). The electrode 13 is therefore in such a spatial position that the glow discharge current can branch to the cathode 11 of the switch and to the opposite electrode 14, which is approximately at the same potential as the cathode 11. The current branching is preferably carried out such that only a small part of the glow discharge current flows in the direction of the cathode 11 of the switch, which is then amplified by the measures represented in claims 5, 6 and 12 to 15. In order to achieve a fluctuation-free sequence of the switching process, it is advisable to set the current branch in such a way that a significant continuous current reaches the area of the hole 5 of the cathode 11. (Typical values for this continuous current, which can be selected in a real arrangement, are between 10⁻⁷A and 10⁻⁵A). This charge carrier current, which gets into the hole 5 of the cathode 11 of the switch, has the effect that a weak background plasma is constantly present here. This has to As a result, the stochastic fluctuations when triggering the switching process are small. In a sense, there is no need to wait for the electron to trigger the pseudo-spark discharge, so that the stochastically fluctuating waiting statistics do not come into play, but smaller statistical fluctuations do occur, which depend on the thickness of the continuously present plasma in the cathode hole area. The constant presence of such a charge carrier current has the consequence that the strength of the plasma additionally injected by a trigger process or the strength of a plasma additionally triggered by targeted photoelectric interaction by illuminating the space 7 behind the cathode 11 can be kept low. Analogously, the precision of triggering the switching process when an overvoltage is reached in the case of claims 25 to 27 is substantially improved by such a constant charge carrier current.

Ein besonderer Vorteil des erfindungsgemäßen Schalters besteht auch darin, dass er sogar dann gezündet werden kann, wenn gemäß den Ansprüchen 13, 14 und 15 durch Umkehr der Polung die Kathode 11 zur Anode und die Anode 12 zur Kathode wird. Bei Thyratrons ist das nicht möglich.A particular advantage of the switch according to the invention is that it can be ignited even if, according to claims 13, 14 and 15, the cathode 11 becomes the anode and the anode 12 the cathode by reversing the polarity. This is not possible with thyratrons.

Die Ansprüche 26 und 27 beschreiben ein neues Triggerverfahren des Pseudofunkenschalters. Es beruht darauf, dass die Auslösung des Schaltvorgangs durch das Überschreiten der Durchbruchsspannung in einem äußeren Schaltkreis erfolgt. Dies findet jedoch statt bei Anwesenheit der Gleichstrom-Glimmentladung, die durch die Löcher 6 in dem abgeschirmten Hohlraum 7 hinter der Kathode 11 (die im Beispiel des Anspruchs 13, 14 und 15 zur Anode wird) mit den Löchern 5 und 8 in den Hauptelektroden 11 und 12 des Pseudofunkenschalters in Wechselwirkung steht. In neuartiger Weise Weise tritt dabei in den durch die Löcher 5 und 8 definierten Kanal der erwähnte Ladungsträgerstrom ein, der den Durchbruchspunkt auf der Zündspannungskennlinie geringfügig absenkt, ausserdem jedoch die erwähnte Verringerung der statistischen Fluktuationen der Schaltverzögerung zur Folge hat, da stets eine große Zahl von Ladungsträgern im Beschleunigungsfeld des Schalters anwesend ist. Auch die Zuverlässigkeit des Schaltens wird in hohem Maße durch diesen Dunkelstrom verbessert. Hiermit erschließt der neue Schalter Anwendungsbereiche, bei denen in anderen Verfahren zur Ladungsträgererzeugung ganz wesentlich eine radioaktive Vorionisierung notwendig ist, nämlich:

  • 1) Einsatz des Pseudofunkenschalters in einer Schaltkette von Marx-Generatoren (bisherige Triggermethode: durch Photostrom aus Hochleistungslasern, durch radioaktive Strahler zur Vorionisierung, und durch Spark-Gaps mit Inkaufnahme von hohen Jitterwerten.)
  • 2) Einsatz des Pseudofunkenschalters in Überspannungsschaltern (sogenannte Überspannungsableiter). Handelsübliche Überspannungsableiter verwenden ebenfalls oft ein radioaktives Präparat zur Vorionisierung, um scharf triggern zu können.
  • 3) Einsatz in Crowbar-Schaltern zum Schutz elektrischer Anlagen und Maschinen.
  • 4) Verwendung als Impulsgenerator und Impulsformer (z.B. als Kleinschalter oder auch als Transferelement zur Übertragung elektrischer Energie in Pulse-Power-Anlagen).
Claims 26 and 27 describe a new trigger method of the pseudo-radio switch. It is based on the fact that the switching process is triggered when the breakdown voltage is exceeded in an external circuit. However, this takes place in the presence of the DC glow discharge through the holes 6 in the shielded Cavity 7 behind the cathode 11 (which becomes the anode in the example of claim 13, 14 and 15) interacts with the holes 5 and 8 in the main electrodes 11 and 12 of the pseudo-spark switch. In a new way, the aforementioned charge carrier current enters the channel defined by holes 5 and 8, which slightly lowers the breakdown point on the ignition voltage characteristic curve, but also results in the aforementioned reduction in statistical fluctuations in the switching delay, since there is always a large number of Charge carriers are present in the acceleration field of the switch. The reliability of switching is also greatly improved by this dark current. The new switch hereby opens up areas of application in which radioactive preionization is essential in other processes for charge carrier generation, namely:
  • 1) Use of the pseudo radio switch in a switching chain of Marx generators (previous trigger method: by photocurrent from high-power lasers, by radioactive emitters for pre-ionization, and by spark gaps with the acceptance of high jitter values.)
  • 2) Use of the pseudo-radio switch in overvoltage switches (so-called surge arresters). Commercial surge arresters also often use a radioactive preparation for pre-ionization in order to be able to trigger sharply.
  • 3) Use in crowbar switches to protect electrical systems and machines.
  • 4) Use as a pulse generator and pulse shaper (e.g. as a small switch or as a transfer element for the transmission of electrical energy in pulse power systems).

Die Weiterbildung des Schalters gemäß Anspruch 25 eignet sich besonders zur Verwendung als Überspannungsableiter. Dabei kann durch äussere, im allgemeinen passive elektrische Maßnahmen der Löschvorgang des Schalters 30 (Fig. 5) so ausgeführt werden, dass für den gegen Überspannung zu schützenden Verbraucher eine durch das Triggern des Schalters vorgesehene Regelspannung definierbar wird. Fig. 5 erläutert den Einsatz des Schalters 30 für eine solche Anwendung. Die Spannung zwischen den Anschlußpunkten 26, 27 soll durch einen Strom-Bypass gesenkt werden, falls ein bestimmter Wert U der Spannung überschritten wird. Die Regulierung hört auf, sobald dieser Wert durch das Ansprechen des Schalters wieder unter die Spannung U abgesenkt wurde. Dies wird erreicht, indem z.B. ein RC-Glied 28, 29 zwischen den Schalter 30 und den Verbraucher (Anschlußpunkte 26 und 27) geschaltet wird (wobei die Kapazität C (28) parallel zum Schalter 30 liegt). Auf diese Weise wird bei Zündung des Schalters 30 der Kondensator 28 fast vollständig entladen. Nach kurzer Zeit löscht der Schalter 30. Er zündet erneut, falls nach Wiederanstieg der Spannung am gelöschten Schalter 30 die Spannung an den Anschlußpunkten 26, 27 des zu regulierenden Verbrauchers noch nicht genügend abgesenkt wurde. Er zündet nicht, falls die Absenkung der Spannung im gewünschten Maße stattgefunden hat. Andernfalls wiederholt sich das Spiel so häufig, bis die Spannung unter den vorgegebenen Wert abgesenkt ist.The development of the switch according to claim 25 is particularly suitable for use as a surge arrester. The extinguishing process of the switch 30 (FIG. 5) can be carried out by external, generally passive electrical measures such that a control voltage provided by triggering the switch can be defined for the consumer to be protected against overvoltage. Fig. 5 explains the use of the switch 30 for such an application. The voltage between the connection points 26, 27 is to be reduced by a current bypass if a certain value U of the voltage is exceeded. The regulation stops as soon as this value has been lowered below the voltage U again by the response of the switch. This is achieved, for example, by connecting an RC element 28, 29 between the switch 30 and the consumer (connection points 26 and 27) (the capacitance C (28) being parallel to the switch 30). To this When the switch 30 is ignited, the capacitor 28 is almost completely discharged. After a short time, the switch 30 extinguishes again if, after the voltage at the deleted switch 30 has risen again, the voltage at the connection points 26, 27 of the consumer to be regulated has not yet been sufficiently lowered. It does not ignite if the voltage has been reduced to the desired extent. Otherwise, the game repeats itself until the voltage drops below the specified value.

Ein triggerbarer Marx-Generator kann so aufgebaut werden, dass von der Schalterkette in einem mehrstufigen Marx-Generator ein Schalter in der üblichen Weise getriggert wird, während die anderen hintereinander geschalteten Schalter durch Anwendung des Verfahrens gemäß Anspruch 26 oder 27 mit hoher Zeitschärfe zum Durchbruch gelangen.A triggerable Marx generator can be constructed in such a way that a switch is triggered by the switch chain in a multi-stage Marx generator in the usual way, while the other switches connected in series achieve a breakthrough with high time accuracy by using the method according to claim 26 or 27 .

Durch die erfindungsgemäße Verlängerung des Weges, auf dem längs der Oberfläche der isolierenden Wand 9 eine Gleitentladung ablaufen kann, lassen sich Schalter konstruieren, die bei sehr hohen Haltespannungen betrieben werden können. Eine technische Grenze wird je nach Füllgas erreicht zwischen etwa 50 und 100 kV. Zur Vermeidung von Instabilitäten ist nämlich der dazu notwendige Druck p möglichst groß zu wählen, was bei vorgegebener Haltespannung zu der Notwendigkeit führt, den Elektrodenabstand (d) möglichst klein zu wählen. Die technische Grenze wird dann durch die Feldemission von Elektronen im Bereich der Löcher 5, 8 gesetzt sowie durch die Tatsache, dass bei kleinen Abständen d zwischen Anode 12 und Kathode 11 und relativ großen Löchern 5, 8 darin Instabilitäten und Fluktuationen wegen der dann extrem steilen Zündspannungs-Kennlinie besonders leicht auftreten. Es ist daher von Vorteil, zwischen Kathode 11 und Anode 12 wie in den Figuren 6 bis 8 dargestellt Zwischenelektroden 31 (Fig. 6) bzw. 34 (Fig. 7 und 8) vorzusehen, die entweder freiflutend angeordnet oder ausserhalb der Gasentladungskammer mit Spannungsteilern verbunden sind, durch die im Falle dreier Zwischenelektroden z.B. die nachstehenden Potentiale an die Elektroden gelegt werden, bezogen auf das Potential der Kathode 11:

Figure imgb0001
By extending the path according to the invention along which a sliding discharge can run along the surface of the insulating wall 9, switches can be constructed which can be operated at very high holding voltages. Depending on the filling gas, a technical limit is reached between approximately 50 and 100 kV. To avoid instabilities, the pressure p required for this must be chosen as large as possible, which is necessary for a given holding voltage leads to the electrode gap (d) being as small as possible. The technical limit is then set by the field emission of electrons in the area of the holes 5, 8 and by the fact that with small distances d between the anode 12 and cathode 11 and relatively large holes 5, 8, instabilities and fluctuations therein due to the then extremely steep Ignition voltage characteristic curve occur particularly easily. It is therefore advantageous to provide intermediate electrodes 31 (FIG. 6) and 34 (FIGS. 7 and 8) between cathode 11 and anode 12, as shown in FIGS. 6 to 8, which are either arranged to be free-flowing or connected to voltage dividers outside the gas discharge chamber through which, in the case of three intermediate electrodes, the following potentials are applied to the electrodes, based on the potential of the cathode 11:
Figure imgb0001

Durch diese Zwischenelektroden 31 bzw. 34, welche zweckmässigerweise parallel zur Kathode 11 und Anode 12 verlaufen, wird die Spannungsfestigkeit wesentlich erhöht. Der Druck kann bei gegebenem Abstand von Kathode 11 und Anode 12 über die Zwischenelektroden 31, 34 hinweg auch bei hohen Haltespannungen relativ hoch sein und die elektrische Feldstärke wird in den einzelnen Bereichen zwischen den Elektroden 11, 12, 31, 34 verhältnismäßig klein. Dies führt zu einer wesentlichen Erhöhung der Stabilität des Schaltsystems gegenüber Fluktuationen, zu einer Reduzierung des Gasverbrauchs und zu einer wesentlichen Reduzierung der Sputterrate des Elektrodenmaterials. Darüberhinaus ist auch die Anfälligkeit gegen Gleitentladungen längs der isolierenden Wand 9 wegen der Herabsetzung der Feldstärke stark vermindert. Ausführungsformen eines solchen Schalters sind Gegenstand der Ansprüche 20 und 21.The dielectric strength is significantly increased by these intermediate electrodes 31 and 34, which expediently run parallel to the cathode 11 and anode 12. The pressure can be at a given distance from cathode 11 and anode 12 the intermediate electrodes 31, 34 are relatively high even at high holding voltages, and the electric field strength becomes relatively small in the individual areas between the electrodes 11, 12, 31, 34. This leads to a substantial increase in the stability of the switching system against fluctuations, to a reduction in gas consumption and to a substantial reduction in the sputtering rate of the electrode material. In addition, the susceptibility to sliding discharges along the insulating wall 9 is greatly reduced because of the reduction in the field strength. Embodiments of such a switch are the subject of claims 20 and 21.

Im Falle des Anspruchs 20 sind die Zwischenelektroden 31 als parallele Platten zwischen Kathode 11 und Anode 12 in die isolierende Wand 9 eingebaut worden.In the case of claim 20, the intermediate electrodes 31 have been installed in the insulating wall 9 as parallel plates between the cathode 11 and the anode 12.

Im Falle des Anspruchs 21 ist bei den Zwischenelektroden 34 die im Anspruch 1 bzw. Anspruch 3 für die Anode 12 und die Kathode 11 gegebene technische Lehre verwirklicht, indem auch bei den Zwischenelektroden 34 die Verbindungslinien 33 zwischen den Zwischenelektroden 34, an denen Metall, Gas und Isolator 9 zusammenstoßen, durch einen Spalt 3a vor dem Eindringen des elektrischen Feldes, ausgehend von den jeweils gegenüberliegenden Elektroden, geschützt sind. Um dies zu erreichen, sind die Zwischenelektroden als hohle Scheiben ausgebildet, die nur in der Mitte ihres Umfangs einen ringförmigen Vorsprung haben, mit dem sie in der isolierenden Wand 9 gehalten werden.In the case of claim 21, the technical teaching given in claim 1 or claim 3 for the anode 12 and the cathode 11 is realized in the intermediate electrodes 34 by the connecting lines 33 between the intermediate electrodes 34, on which metal, gas, are also present in the intermediate electrodes 34 and insulator 9 collide, are protected by a gap 3a against the penetration of the electric field, starting from the respectively opposite electrodes. In order to achieve this, the intermediate electrodes are designed as hollow disks which only have an annular projection in the middle of their circumference, with which they are held in the insulating wall 9.

In beiden Fällen haben natürlich die Zwischenelektroden 31 und 34 Löcher 32 bzw. 35, die fluchten und dadurch einen Kanal bilden, in welchem die Pseudofunkenentladung abläuft.In both cases, of course, the intermediate electrodes 31 and 34 have holes 32 and 35, respectively, which are aligned and thereby form a channel in which the pseudo-spark discharge takes place.

Der Hohlraum in den Zwischenelektroden 34, wie sie im Ausführungsbeispiel gemäß Fig. 7 dargestellt sind, ist im wesentlichen ein feldfreier Raum. In der Weiterbildung des Schalters, die Gegenstand des Anspruchs 22 ist und in Fig. 8 dargestellt ist, befindet sich in dem Hohlraum der Zwischenelektroden 34 ein Schirmblech 36, welches den geraden Weg zwischen der Kathode 11 und der Anode 12 unterbricht. Damit die Ladungsträger dennoch von der Anode zur Kathode gelangen können, darf das Schirmblech den Durchgang durch die jeweilige Zwischenelektrode 34 natürlich nicht vollständig versperren. Zweckmässigerweise sind deshalb abseits der Löcher 35 im Schirmblech 36 Löcher 37 vorgesehen, durch die hindurch die Ladungsträger auf einem Umweg zur Anode gelangen können. Der Vorteil dieser Maßnahme liegt darin, dass die Spannungsfestigkeit weiter erhöht wird. Weitere Vorteile liegen darin, dass die Energieverluste des Schalters geringer werden, weil die Elektronen nicht mehr so stark beschleunigt werden. Eine weitere positive Folge davon ist , dass weniger Röntgenstrahlung auftritt und weniger Schäden an den Teilen der Gasentladungskammer auftreten. Trotz der Schirmbleche 36 läuft eine Pseudofunkenentladung ab, weil das Plasma durch die seitlichen Löcher 37 in den Schirmblechen koppelt.The cavity in the intermediate electrodes 34, as shown in the exemplary embodiment according to FIG. 7, is essentially a field-free space. In the further development of the switch, which is the subject of claim 22 and is shown in FIG. 8, there is a shield plate 36 in the cavity of the intermediate electrodes 34, which interrupts the straight path between the cathode 11 and the anode 12. So that the charge carriers can nevertheless get from the anode to the cathode, the shield plate must of course not completely block the passage through the respective intermediate electrode 34. Therefore, apart from the holes 35, holes 37 are expediently provided in the shield plate 36, through which the charge carriers can reach the anode in a detour. The advantage of this measure is that the dielectric strength is further increased. Further advantages are that the energy losses of the switch are reduced because the electrons are no longer accelerated as much. Another positive consequence of this is that there is less X-ray radiation and less damage to the parts of the gas discharge chamber. Despite the shield plates 36, a pseudo-spark discharge takes place because the plasma couples through the lateral holes 37 in the shield plates.

Die Weiterbildung gemäß den Ansprüchen 23 und 24, dargestellt in Fig. 9, trägt der Möglichkeit des Pseudofunkenschalters, in parallel geschalteten Systemen verwendet zu werden, Rechnung. Insbesondere wegen des weitgehend fluktuationsfreien Aufbaus der Gasentladung, welche durch die Triggerung mit einer Glimmentladung gewährleistet ist, können Pseudofunkenschalter parallel betrieben werden, wenn sie innerhalb eines nicht zu großen Zeitintervalls getriggert werden. Es hat sich gezeigt, dass dieses Zeitintervall von der Größenordnung des Impulsanstiegs des Schalters sein muss. In niederohmigen Systemen liegen die Anstiegszeiten des Schaltimpulses in der Größenordnung 10⁻⁸s, so dass bei einer zeitlichen Fluktuation des Sehaltvorgangs in der Größenordnung von 1 bis 2 ns, wie sie für die Schalter realistisch sind, ein Parallelschalten von mehreren Schaltern im Betrieb möglich ist. Auf diese Weise lassen sich großflächige Schaltarrangements aufbauen, die überdies extrem niederinduktiv sind und bei denen eine Stromverteilung auf parallelgeschaltete Systems vorgenommen werden kann, was zu einer Begrenzung der Belastung der einzlenen Schaltteile führt. Notwendig für einen langzeitigen Betrieb solcher Systeme ist jedoch, dass bei vorgegebenen geometrischen Dimensionen der Schalter der Gesamtgasdruck in allen Systemen gleich gehalten werden muss. Wegen des Gasverbrauchs empfiehlt es sich daher, die Schalter 42 kommunizierend an ein gemeinsames Rohrleitungssystem 43 anzuschließen, über welches sie mit einem gemeinsamen Gasspeicher 44 verbunden sind, von dem aus sie, vorzugsweise mit Unterstützung durch einen Druckregler, mit dem Gas versorgt werden.The development according to claims 23 and 24, shown in FIG. 9, takes into account the possibility of the pseudo-radio switch to be used in systems connected in parallel. In particular because of the largely fluctuation-free structure of the gas discharge, which is ensured by triggering with a glow discharge, pseudo-spark switches can be operated in parallel if they are triggered within a not too large time interval. It has been shown that this time interval must be of the order of the pulse increase of the switch. In low-resistance systems, the rise times of the switching pulse are in the order of magnitude of 10 sos, so that with a temporal fluctuation of the holding process in the order of 1 to 2 ns, such as they are realistic for the switches, a parallel connection of several switches is possible during operation. In this way, large-area switching arrangements can be built which are also extremely low-inductance and in which current can be distributed to systems connected in parallel, which leads to a limitation of the load on the individual switching parts. For long-term operation of such systems, however, it is necessary that the total gas pressure must be kept the same in all systems for given geometrical dimensions of the switch. Because of the gas consumption, it is therefore advisable to connect the switches 42 in a communicating manner to a common pipeline system 43, via which they are connected to a common gas store 44, from which they are supplied with the gas, preferably with the support of a pressure regulator.

Claims (27)

1. A gas-electronic switch having a gas discharge chamber, which contains two metal electrodes, namely, a cathode (11) and an anode (12), which are spaced a distance (d) aparat and are separated from each other by an electrically insulating wall (9a) of the gas discharge chamber made of ceramic material or glass, wherein the cathode (11) has a hole (5) and the electrodes (11, 12) are joined to the insulating wall (9a) by a tight metal-ceramic joint or fused joint, and wherein the gas discharge chamber is filled with an ionizable low-pressure gas under such a pressure p that the product p x d has such a value that a gas discharge between the electrodes (11, 12) will be fired in response to a voltage applied thereto which is disposed in that branch of the firing voltage vs. pressure characteristic in which the firing voltage decreases as the pressure rises, characterized in that for at least one of the two electrodes (11, 12) the lines of contact (4) at which the electrode (11, 12) which is considered, the gas and the insulating wall (9a) meet are spaced from the respective opposite electrode (12, 11) by a smallest distance which is larger than (d) and the electrode (11, 12) which is considered is separated from the insulating wall (9a) by a gap (3) which has a width that is smaller than (d).
2. A switch according to claim 1, characterized in that the anode (12) has a hole (8) that is opposite to the hole (5) in the cathode (11).
3. A switch according to claim 1 or 2, characterized in that for the cathode (11) as well as for the anode (12) the lines of contact (4) at which the metal of the electrode (11 , 12) which is considered, the gas and the insulating wall (9a) meet are spaced from the respective opposite electrode (12, 11) by a smallest distance which is larger than (d) and the electrodes (11, 12) are spaced from the insulating wall (9a) by a gap (3), which has a width that is smaller than (d).
4. A switch according to any of the preceding claims, characterized in that the gap (3) is much smaller than (d), preferably smaller than 1 mm, and best is as small as is technically possible.
5. A switch according to claim 1, characterized in that a cage is provided in the space behind the cathode (11) and is constituted by a cavity (7), which is surrounded by a metal wall (2) and has openings (5, 6), which consist of the hole (5) in the cathode (11) and of at least one additional opening (6), which connects the cavity (7) to the space behind the cathode,
   that two additional electrodes (13, 14) are disposed in the space behind the cathode and are so connected in circuit that a low-pressure gas discharge (10) can be sustained between them, so that when the switch is in a stand-by state, before the pseudospark between the cathode (11) and the anode (12) is fired, a small partial current of charge carriers will flow from the low-pressure gas discharge through the cavity (7) and through the hole (5) in the cathode (11) to the anode (12).
6. A switch according to claim 5, characterized in that the additional electrodes (13, 14) are so connected in circuit that a low-pressure gas discharge is sustained between them throughout the operation of the switch.
7. A switch according to claim 5, characterized in that the additional openings (6) in the wall (2) of the cavity (7) which is disposed behind the cathode (11) and constitutes a cage are so shielded by metal shields (15) or by the additional electrodes (13, 14) in the space behind the cathode that the insulating wall (9b, 9c, 9d, 9e) of the gas discharge chamber cannot be reached on a straight path from the interior of the cavity (7).
8. A switch according to any of claims 1 and 5 to 7, characterized in that at least those portions of the electrodes (11 to 14), of the metal shields (15) and of the wall (2) of the cavity (7) behind the cathode (11) as well as the rear wall of the space behind the cathode and optionally also the rear wall of the space behind the anode, at least in those portions which are particularly highly stressed by the gas discharge, are made of a hardmetal, such as tungsten, tantalum, molybdenum, or of alloys containing said metals, or a chromium-copper composite material.
9. A switch according to claim 1, characterized in that one or more metal shields (18) are arranged on the cathode (11) and/or on the anode (12) in such a manner that light from the gas discharge struck between the cathode (11) and the anode (12) in the region between their openings (5, 8) cannot directly reach the insulating wall (9a) which surrounds the gas discharge chamber.
10. A switch according to claim 5, characterized in that shields (15, 16, 17) are disposed between the insulating wall (9a to 9e) of the gas discharge chamber and the additonal electrodes (13, 14), between which a direct-current glow discharge for triggering the pseudospark is maintained, and said shields (15, 16, 17) are so arranged that the plasma of the glow discharge is substantially unable to illuminate the insulating wall (9a to 9e) on a straight path.
11. A switch according to any of the preceding claims, characterized in that the filling gas consists of hydrogen or heavy hydrogen (deuterium) or of a mixture of said two gases, a hydrogen accumulator consisting of an absorptive metal accumulator (22) is provided, which consists, e.g., of titanium, zirconium and/or palladium or of another metal or of a metal alloy which is adapted to adsorb hydrogen and to subsequently release hydrogen in response to a supply of heat to the accumulator, and heating means (19, 21) and a pressure regulator acting on the heating means are provided so that the pressure of the gas which fills the gas discharge chamber can be automatically controlled at a predetermined value.
12. A switch according to claim 5 and preferably according to any other of the preceding claims, characterized in that a voltage source that is capable of a pulsed operation is provided and is connected either to the additional electrodes (13, 14), between which the low-pressure gas discharge used to fire the pseudospark is sustained, or is connected to auxiliary electrodes, which are disposed in the space behind the cathode and which act in such a manner on the low-pressure gas discharge sustained between the additional electrodes (13, 14) that the injection of charge carriers from that low-pressure gas discharge into the cavity (7) behind the cathode (11) is pulse-like intensified to fire the pseudospark.
13. A switch according to claim 5 and preferably according to any other of the preceding claims, characterized in that a cage which is constituted by a cavity (23) which is surrounded by a metal wall is provided behind the anode (12).
14. A switch according to claim 13, characterized in that the cavity (23) behind the anode (12) is similar in size to the cavity (7) behind the cathode (11).
15. A switch according to claim 13 or 14, characterized in that switching means are provided for interchanging the polarities of the cathode (11) and the anode (12).
16. A switch according to claim 5 and preferably according to any other of the preceding claims, characterized in that the cathode (11) has a plurality of holes (24) and each of said holes (24) opens into a cavity (7), which is provided behind the cathode and is surrounded by a metal wall (2) and in which at least one additional opening (6) is provided, which connects the cavity (7) to the space behind the cathode.
17. A switch according to claim 16, characterized in that the holes (24) in the cathode (11) open into a common cavity (7) behind the cathode (11).
18. A switch according to claim 16 or 17, characterized in that the anode has holes (8, 25) which are equal in number to those in the cathode (11) and are opposite to and aligned with the holes (5, 24) in the cathode (11).
19. A switch according to claim 16, 17 or 18, characterized in that it has an axis of symmetry (40), which extends through the cathode (11) and the anode (12) at right angles thereto and the holes (5, 24; 8, 25) provided in the cathode (11) and optionally in the anode (12) are symmetrically arranged with respect to the axis of symmetry (40).
20. A switch according to any of the preceding claims, characterized in that its breakdown voltage is increased by the provision of one or more interposed electrodes (31 and 34), which are disposed between and electrically insulated from the anode (12) and the cathode (11) and have holes (32), which are aligned with the hole (5) and optionally with the additional holes (24) in the cathode (11).
21. A switch according to claim 20, characterized in that at least one of the interposed electrodes (34) is so designed and arranged that for said interposed electrodes the lines of contact (33) where the metal of the interposed electrode (34), the gas and the insulating wall (9) of the gas discharge chamber meet are spaced from the respective adjacent electrode (11 or 12 or 34) by a smallest distance which is larger than the distance between the interposed electrode (34) and the respective adjacent electrode (11 or 12 or 34) , adjacent to their holes (5, 8, 35) and that the interposed electrodes (34) are separated from the insulating wall (9) by a gap (3a) which has a width that is smaller than said distance.
22. A switch according to claim 21, characterized in that the interposed electrodes (34) are hollow and in their cavity contain a sheet metal shield (36), which interrupts the straight path between the cathode (11) and the anode (12) and compels the charge carriers to take a detour as they flow from the cathode (11) to the anode (12).
23. A switch according to any of the preceding claims, characterized in that the gas discharge chamber has an inlet (41) for supplying the filling gas from the outside.
24. An arrangement consisting of a plurality of switches according to claim 23, wherein the switches (42) are interconnected in parallel by pipes (43), which are also connected to a gas accumulator (44).
25. The use of a switch according to any of claims 1 to 22 as an overvoltage arrester in an electric network, to which the switch is connected in such a manner that the switch will be fired when the voltage between two terminals (26, 27) of the network exceeds a predetermined value and that the switch will discharge energy from said network until the voltage has decreased below said predetermined value, characterized in that electric components, particularly a resistance-capacitance circuit (28, 29), are connected between the switch (30) and the network and adapt the predetermined voltage between the terminals (26 and 27) to the firing voltage of the switch (30).
26. A method of operating a switch according to claim 5 and preferably according to any further of claims 6 to 25, characterized in that a slight charge carrier stream, which in itself is not sufficient to fire the pseudospark, is always supplied from the low-pressure glow discharge, which is permanently sustained between the additional electrodes (13) and (14) and the anode, and that the pseudospark is fired in that the voltage between the cathode (11) and the anode (12) is increased above the breakdown voltage by an action from the outside.
27. A method according to claim 26, characterized in that the voltage between the cathode (11) and the anode (12) is increased by switching pulses in the switching circuit of the switch.
EP88905787A 1987-06-30 1988-06-30 Gaz electronic switch (pseudo-spark switch) Expired - Lifetime EP0324817B1 (en)

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DE3721529 1987-06-30
DE19873721529 DE3721529A1 (en) 1987-06-30 1987-06-30 TRIGGERING AND ISOLATION OF PSEUDO SPARK SWITCHES

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EP0324817A1 EP0324817A1 (en) 1989-07-26
EP0324817B1 true EP0324817B1 (en) 1992-08-12

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EP88905787A Expired - Lifetime EP0324817B1 (en) 1987-06-30 1988-06-30 Gaz electronic switch (pseudo-spark switch)

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Country Link
US (1) US5091819A (en)
EP (1) EP0324817B1 (en)
JP (1) JPH02500868A (en)
DE (2) DE3721529A1 (en)
WO (1) WO1989000354A1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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WO1995019651A1 (en) * 1994-01-13 1995-07-20 Centre National De La Recherche Scientifique (Cnrs) Pseudospark switch triggered by a corona discharge

Also Published As

Publication number Publication date
DE3873729D1 (en) 1992-09-17
US5091819A (en) 1992-02-25
WO1989000354A1 (en) 1989-01-12
EP0324817A1 (en) 1989-07-26
JPH02500868A (en) 1990-03-22
DE3721529A1 (en) 1989-01-12

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