US2835836A - Gas discharge device - Google Patents

Description

May 20, 1958 HSIUNG HSU GAS DISCHARGE DEVICE Filed June 20, 1955 FIGS. 2 AND 4 INPUTCURRENT INVENTORZ HSIUNG HSU.

} BY HI ATT RNEY.

GAS DISCHARGE DEVICE Hsiung Hsu, Liverpool, N. Y., assignor to General Electric Company, a corporation of New York Application June 20, 1955, Serial No. 516,532

13 Claims. (Cl. 313-71) My invention relates to improvements in gas discharge devices and pertains more particularly to improvements in gas amplifier tubes.

One type of gas amplifier tube generally comprises a sealed envelope containing a gaseous filling or ionizable medium, such as xenon, a main cathode, a main anode, and an auxiliary cathode. In the tube there are separate discharge paths for a load current and an ionizing current. The energizing potential required to draw the load current between the main cathode and the main anode is set at a value substantially below the value required to produce ionization of the filling or ionizable medium. A higher potential is applied between the auxiliary cathode and the main anode to maintain a separate ionizing or auxiliary discharge. The auxiliary discharge ionizes the gaseous filling for thereby converting it into a plasma constituted of positive ions and detached, free negative electrons. The free, negative electrons are attracted to the main anode and the heavier positive ions tend to surround the main cathode and fill the load current discharge path or inter-electrode region between the main cathode and anode. Thus, the positive ions serve to neutralize the electron space charge surrounding the main cathode and serve eifectively as a low impedance conductor extending between the main cathode and the main anode. Due to these elfects the tube output current is generally substantially larger than the input current or, in other words, the tube provides a current amplification effect. The amount of current output depends on the density of the plasma between the main cathode and anode and the amount of ionizing or input current required to provide the plasma.

Now, in the ordinary gas amplifier tube the input current comprises electrons which travel toward and into the inter-electrode region intermediate the main cathode and anode. These electrons generate the plasma in the inter-electrode region which is required for the operation of the tube. Additionally, the input current comprises a substantial number of electrons which do not enter the inter-electrode region but which flow directly from the auxiliary cathode to the main cathode and to the edges and surface portions of the anode including the sides of the anode opposite the main cathode. These last-mentioned electrons are undesirable in that they increase the input current required to operate the tube without assisting in the generation of useful plasma in the inter-electrode region between the main cathode and anode. Thus, the current amplification eifect of the tube is decreased. This limits substantially the applications of the tube. Additionally, the mentioned undesirable electrons increase substantially the tube noise.

Accordingly, the primary object of my invention is to provide a new and improved current amplification device.

Another object of my invention is to provide a current amplifying gas tube including new and improved means for increasing the current amplification effect thereof.

Another object of my invention is to provide a current amplifying tube including new and improved means for reducing the current input required to provide a predetermined amplified current output.

Another object of my invention is to provide a current amplifying gas tube including new and improved means for reducing noise in the operation thereof.

Still another object of my invention is to provide a new and improved current amplifying device including means adapting the device for increased applications.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out in particularity in the claims annexed to and forming part of this specification.

In carrying out the objects of my invention I provide a sealed envelope containing an ionizable medium, a main cathode and a main anode in cooperative spaced relation and an auxiliary cathode adapted for maintaining an ionizing discharge and thereby generating a plasma between the main cathode and anode. Cooperating with the auxiliary cathode is means adapted for directing the ionizing discharge into the space between the main anode and main cathode and for minimizing the direct effects of the discharge on the main cathode and anode. Additionally, the last-mentioned means may be adapted for collecting electrons emitted from the main cathode.

For a better understanding of my invention. reference may be had to the accompanying drawing in which:

Fig. l is an enlarged elevation view of a gas discharge device partially broken away to illustrate an embodiment of my invention incorporated therein;

Fig. 2 is an enlarged sectional view taken along the lines 2-2 in Fig. l and looking in the direction of the arrows.

Fig. 3 is a schematic circuit diagram of an amplifier system using the tube shown in Figs. 1 and 2;

Fig. 4 is a cross-sectional view similar to that of Fig. 2 and illustrating another embodiment of my invention;

Fig. 5 is a cross-sectional view similar to that of Fig. 2 and illustrating still another embodiment of my invention;

Fig. 6 is a schematic circuit diagram of an. amplifier system using the tube shown in Fig. 5; and

Fig. 7 is a graph that shows the output current versus input current of diiferent types of gas amplifier tubes including tubes incorporating my invention.

Referring to Fig. 1, there is shown a gas amplifier tube incorporating an embodiment of my invention and generally designated 1. The tube 1 comprises a sealed insulative envelope 2 and an insulative base 3 carrying a plurality of pins or prongs 4 electrically connected to leads (not shown) extending in a sealed manner through the lower end of the envelope and adapted for providing electrical connections to various electrode elements contained in the envelope. Additionally, the envelope 2 is charged or filled with an ionizable medium or filling which may be xenon gas or any of the other gases which are well-known by those skilled in the art to be suitable for use in gas tubes of the presently considered type.

In the envelope 2 the electrodes are supported in spaced insulated relation between a pair of spaced insulators 5 which may comprise the conventional mica disks. As perhaps better seen in Fig. 2 the mentioned electrode elements include a main cathode 6 which may be of the familiar indirectly heated type comprising a substantially fiat elongated metallic sleeve 7 coated with a suitable electron emissive material and containing a suitable filamentary heater 8.

Supported between the disks 5 in spaced relation to the main cathode 6 is a main anode 10. The anode 1i) may comprise a three sided sheet metal structure as shown or may be of any similar construction which would cause it to fit almost completely about the cathode J1 and thereby adapt it for maximum collection of electrons emitted by the cathode 6 while providing a suitable entrance for an ionizing discharge into the inter-electrode region between the main cathode and anode.

Positioned between the insulative supports in spaced relation to themain cathode and anode and disposed in front of the entrance into the main anode is a second or auxiliary cathode 11. The auxiliary cathode It may also be of the indirectly heated type and, as shown, it

may comprise a cylindrical metal sleeve 12 having a in construction to the anode and is disposed so that the side edges thereof extend to positions adjacent the edges of the main anode 10 and the open side or discharge aperture provided by the shield is adjacent to or coincides with the entrance to the inter-electrode region between the main cathode and anode. Provided in the shield 14 and suitably secured to the opposite side walls is a pair of elongated members 15 adapted for providing a discharge aperture. Additionally, fitted over the ends of the auxiliary cathode I1 and covering the ends of the shield 14 are suitable metal caps or end shields I16 The tube described to this point may be operated in a circuit such as that shown in Fig. 3. In this figure are shown a low-potential load-current-energizing source 17 and a relatively higher potential auxiliarly-discharge-energizing source 18. Any suitable source (not shown) may be providedfor energizing the cathode heaters 8 and 13.

One side of the source is connected through a utilization' device, which may be a loudspeaker 20, to the main anode and the other side is connected to the main cathode and, thus, the source 17 is adapted for maintaining the smaller non-ionizing potential between the main cathode 6 and the anode 10. This is preferably a low impedance source. This type of source is provided because of the fact that although it need not provide much voltage it must, as'will appear, be capable of delivering to the output current utilization device or loudspeaker 29 a substantial signal-bearing current such as a current which may have an average value of the order of one to several amperes.

The source 18, in turn, is required to be capable of providing a relatively higher potential but need not be capable of providing a particularly large continuous average current. This is due to the fact that the source is serves to energize the relatively efficient low-current iOIllZ- ing-discharge.

In the arrangement described the main anode and the main cathode serve conjointly as an anode for attracting and receiving electrons from the auxiliary cathode 11, thereby to establish the auxiliary or ionizing discharge. Thus, the source 18 is connected between the auxiliary cathode 11 and the side of the source 17 connected to the main cathode through a signal generating means 21 which may be one of any number of suitable well-known devices.

Briefly considered, during operation of the just-do scribed circuit, the auxiliary cathode 11 provides an ionizing discharge which is effective for ionizing the gas or ionizable medium thereby to provide a plasma indicated by the stippling generally designated 24 in Fig. 3. Thus, positive ions are provided for neutralizing the space charge between the main cathode and anode thereby to increase greatly the emission from the main cathode or amplifying the current in the output circuit or circuit coupled to the utilization device adapted for being operated by the output current.

Now, I have found that in a system such as that justdescribed, a substantial number of electrons comprising the ionizingdischarge tend to flow to the main cathode and the surfaces of the main anode before they are able to produce effective plasma between the main cathode and anode. These electrons are wasted in that they do not assist in neutralizing the space charge and tend to increase the current input required for a given desired output current, for example, and as indicated by the curve designated A in Fig. 7, an input current of one milliarnpere will result in an output current of only twenty milliamperes. This is not a substantial amplification. A" 'itionally, the electrons which flow to the main cathode and anode without contributing substantially to the production of plasma in the region between the main cathode and anode have the effect of causing substantial tube noise. Accordingly, my invention is intended to 'rinirnize the amount of wasted electrons in the ionizing discharge, thereby to reduce the input current required to obtain a predetermined amplified output current and to reduce noise.

As seen in Figs. 1-3 an embodiment of my invention may include a single elongated electrode element 25 mounted between micas 5 and disposed in a direct or straight line path between the auxiliary and main cathodes and adjacent the latter. Thus, with respect to the auxiliary cathode, the main cathode is located in the shadow of the element 25, or considered from another viewpoint the element 25 is adapted for splitting or dividing the ionizing discharge or stream of electrons in substantially the manner illustrated by the arrows in Fig. 3. As shown, the element 25 is allowed to float electrically or if desired it maybe biased slightly negatively with respect to the auxiliary cathode 11. Accordingly, the stream of electrons comprising the ionizing discharge is split and diverted from the edge of the main cathode and directed into the inter-electrode regions or spaces on either side of the main cathode 6 and between the main cathode and anode for producing plasma between these electrodes. Thus, eiectrons are not Wasted on the edge of the main cathode and greater concentration of positive ions or plasma is provided where it is most useful to neutralize the space charge with the result that emission from the main cathode and output current are correspondinglyv increased. The advantage of this form of my invention is perhaps better appreciated by reference to the curves shown in Fig. '7 whereby it is shown that a given desired output current of approximately two-hundred milliamperes may be obtained with an input current of only one milliampere.

Additionally, tie diversion of the auxiliary discharge from the edge of the main cathode reduces substantially noise tube operation. Reduction of wasted electrons and noise are further eifected by the shield 24 and the members 15 which prevent electrons from flowing dircct ly to the edges and outer surfaces of the main anode.

It is to be understood that while I have illustrated the ciement 25 as being Y-shaped in cross-scction it may assume any desired cross-sectional configuration throughout its length. For example, I have found that a flat metal strip or a metal rod are suitable for splitting the electron stream and diverting the electrons in the abovedescribed manner. Additionally, by carrying the potential applied to the element 25 it is possible to determine and variably control the shadowing effect of the element of the main cathode.

In Fig. 4 is illustrated a modified form of my invention incorporated in a tube generally designated in. In this embodiment the envelope, electrode supports, main cathode, main anode and auxiliary cathode may be identical in structure and purpose to those described above with regard to Figs. l3 and are accordingly re erred to by similar reference characters. The Fig. 4 embodiment differs, however, in that it includes an auxiliary cathode shield 26 which is relatively narrower than the main anode and includes side portions which extend up to the anode entrance and define a discharge aperture that is smaller than the anode entrance. Additionally, this form of my invention includes an elongated conductive element mounted between the usual top and bottom micas and which extends radially for a substantial distance in the straight line path between the cathodes. Element 27 can be allowed to float electrically or be biassed slightly negative with respect to the auxiliary cathode to cause the electron stream to become split or divided with portions thereof diverted from the edge of the main cathode 6 and directed into the spaces or inter-electrode regions intermediate the main cathode and anode. Additionally, the shield 126 causes the outer portions of the divided stream to be diverted from the anode 10 and into the portions of the inter-electrode regions immediately adjacent the main cathode. This results in concentration of the resulting plasma in the portions of the space charge adjacent the cathode where it is efiective in accordance with the invention, to control the space charge and the output current of the device. Additionally, the just-described shielding structure prevents electrons from impinging upon the edges and outer sides of the main anode; Thus, the structure illustrated in Fig. 4 is effective for minimizing the input current required to obtain a predetermined amplified output current in a manner generally similtnar to that of the device of Fig. 2 and also illustrated in Pig. 7. Additionally, noise is reduced in a manner similar to that described above.

in Fig. 5 is illustrated another embodiment of my invention in which the envelope, electrode supports, main cathode, main anode, auxiliary cathode and shield may be identical in structure, and purpose, and numerical designation to those illustrated in Figs. 1-3. The structure of Pig. 5 is different, however, in that it includes an auxiliary discharge splitting electrode element 30 which may be supported between the top and bottom micas and disposed in a straight line path between the cathodes, as shown, element Ed is located adjacent the exit aperture of the auxiliary cathode It and on the auxiliary cathode side of electrode 32 located in the same path between the element 34) and the main cathode 6. Thus, the electrode 31 is in the shadow of the element St and adjacent the main cathode 6. As before, stream-splitting electrode 30 can be allowed to float electrically or biassed slightly negative relative the auxiliary cathode. The electrode 31, as seen in Pig. 6, is adapted for being connected to the anode 1d and to the positive terminal of source 17 through the utilization device, here shown as a loudspeaker 2%.

During the operation of the system shown in Fig. 6, the ionizing discharge or electron stream emanating from the auxiliary cathode 11 is split by the element 30 and thereby diverted from the electrode 31 and cathode 6 and divided into two leg portions. Thereafter, the electrons comprising the leg portions of the split stream tend to impinge upon the side wall portions of the main anode til. However, since the main anode to which the electrode 31 is connected is positive relative to the main cathode, the element 31 is effective for attracting the legs of the electron stream inwardly. This results in the electrons entering the space charge or inter-electrode region adjacent the main cathode, resulting in greater concentration of effective plasma in the portions of the inter-electrode regions immediately adjacent the cathode. It further results in avoidance of substantial electron impingement upon the walls of the main anode. As explained above in connection with the other embodiments, reduction of the input current required for a predetermined amplified output current and a substantial reduction of noise in the operation of the system are accomplished. Additionally, the inward attraction of the legs of the electron stream, as efiected by the element 31,

results in the introduction of plasma between the main v cathode and the element 31 while at the same time the main cathode 6 and electrode 31 are ettectively shielded from the discharge stream. Now, inasmuch as the element 31 is at anode potential, this results in current flow span between the main cathode and the element 341 which results in increased output current. As shown in Fig. 7, with my structure of Fig. 5 a given output current of approximately four hundred milliamperes may be obtained with an input current of only one milliampere as cornpared with two hundred milliarnperes and twenty milliamperes obtainable with the version of Figs. 2 and 4 and prior-known types, respectively.

Thus, it will be seen that I have provided a new and improved gas amplifier tube adapted for operating with a minimal input current for obtaining a predetermined amplified output current and thereby increasing the current amplification eflect of the tube. Additionally, my device provides for substantial reduction of noise. Additionally, dueto the reduced requirement for input cur rent my device is applicable for use in systems including components of relatively small current output such as transistors. Thus, my invention is adapted for increased applications in electron circuits.

While I have shown and described specific embodiments of my invention, I do not desire my invention to be limited to the particular forms shown and described, and I intend by the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A gas discharge device comprising; a sealed envelope containing an ionizable medium, a main cathode and an anode in cooperative spaced relation within said envelope, means including an auxiliary cathode in laterally spaced relation to said main cathode for producing an ionizing discharge to provide a conductive plasma be tween said main cathode and anode, and means for diverting said ionizing discharge from said main cathode and directing said ionizing discharge into the region b tween said main cathode and anode.

2. A gas discharge device comprising; a sealed envelope containing an ionizable medium, a main cathode and an anode in cooperative spaced relation within said envelope, means including an auxiliary cathode for producing an ionizing discharge to provide a conductive plasma between said main cathode and anode, and means effective for diverting said ionizing discharge: from the portion of said main cathode adjacent said auxiliary cathode and directing substantially all of said ionizing discharge into a portion of the region between said main cathode and anode adjacent said main cathode and substantially spaced from said anode.

3. A gas amplifier tube comprising; a sealed envelope containing an ionizable medium, means for carrying a load current through the tube comprising a main cathode and a main anode in cooperative spaced relationship, said anode including portions disposed on either side of said main cathode, means including an auxiliary cathode in laterally spaced relation to said main cathode for producing an ionizing discharge to provide a conductive plasma between said main cathode and anode, and an element interposed between said main and auxiliary cathodes efiective for dividing said ionizing discharge thereby to shield said main cathode from the direct effects of such discharge and to direct a divided portion of said dis-- charge into the inter-electrode region of either side of said main cathode.

4. A gas amplifier tube comprising; a sealed envelope containing an ionizable medium, means for carrying a load current through the tube comprising a main cathode and a main anode in cooperative spaced relationship, said anode including portions disposed on either side of said main cathode, means including an auxiliary cathode for producing an ionizing discharge to provide a conductive plasma between said main cathode and anode, an element interposed between said main and auxiliary cathodes etfective for dividing said ionizing discharge thereby to shield said main cathode from the direct effects of said discharge and to direct a divided portion of said discharge into the inter-electrode region on either side of said main cathode, and means limiting the outer margins of said divided portions of said discharge for effecting concentration thereof in portions of said inter-electrode region adjacent said main cathode.

5. A gas amplifier tube comprising; a sealed envelope containing an ionizable medium, means for carrying a load current through the tube comprising a main cathode and a main anode, said anode including side portions disposed on either side of and in cooperative spaced relationship with said main cathode, means including an auxiliary cathode for producing an ionizing discharge to provide a conductive plasma between said main cathode and anode, a shield disposed about said auxiliary cathode and including side portions extending adjacent to said side portions of said anode, and an element interposed in a direct line path between said cathodes, said element being effective for splitting said ionizing discharge thereby to shield said main cathode from the direct effects of said discharge and to direct plasma producing portions of said discharge into the inter-electrode regions on either side of said main cathode, said shieldv being effective for reducing direct effects of said discharge on said main anode and to concentrate said plasma producing portions of said discharge in portions of said inter-electrode region immediately adjacent said main cathode.

6. A gas amplifier tube comprising; a sealed envelope containing an ionizable medium, means for carrying a load current through the tube comprising a main cathode and a main anode, said anode including side portions disposed on either side of and in cooperative space relationship with said main cathode, the edge portions of said anode defining an entrance for an ionizing discharge, means including an auxiliary cathode for producing an ionizing discharge to provide a conductive plasma between said main cathode and anode, a shield disposed about said auxiliary cathode and including side portions extending to said anode entrance and defining an aperture smaller than said entrance, and an element interposed in a direct line path between said cathodes effective for splitting said ionizing discharge thereby to shield said main cathode from the direct effects of said discharge and to direct plasma producing portions of said discharge through said entrance and into the inter-electrode regions on either side of said main cathode, said shield being effective for directing said plasma producing portions away from said anode and toward the lateral portions of said main cathode.

7. A gas amplifier tube comprising; a sealed'envelope containing an ionizable medium, means for carrying a load through the tube comprising a main cathode and a main anode, said anode including side portions disposed on either side of and in cooperative spaced relationship with said main cathode, the edge portions of said anode defining an entrance for an ionizing discharge, means including an auxiliary cathode for producing an ionizing discharge to provide a conductive plasma between said main cathode and anode, a shield disposed about said auxiliary cathode and including elongated side portions extending to said anode entrance and defining an aperture smaller than said entrance, and an elongated element interposed in and extending a substantial length of a direct line path between said cathodes, said element being effective for splitting said ionizing discharge thereby to shield said main cathode from the direct effects of such discharge and to direct plasma producing portions of said discharge into the inter-electrode region on either side of said main cathode, said shield being effective for directing said plasma producing portions away from said side portions of said main anode and toward the lateral portions of said main cathode.

8. Atgas amplifier tube comprising; a sealed envelope containing an ionizable medium, means for carrying a load current through the tube comprising a main cathode and a main anode in cooperative spaced relationship,

means including an auxiliary cathode in laterally spaced relation to said main cathode for producing an ionizing discharge to provide a conductive plasma between said main cathode and anode, means effective for deflecting said ionizing discharge out of a straight line path between said cathodes, and means effective for directing the deflected portion of said discharge toward the inter-electrode region between said main cathode and anode.

9. A gas amplifier tube comprising; a sealed envelope containing an ionizable medium, means for carrying a load current through the tube comprising a main cathode and a main anode in cooperative spaced relationship, means including an auxiliary cathode for producing an ionizing discharge to provide a conductive plasma between said main cathode and anode, means effective for deflecting said ionizing discharge out of a straight line path between said cathodes whereby said main cathode is substantially shaded from said ionizing discharge, and electrode means adapted for directing the deflected portion of' said discharge toward the surface of said main cathode.

10. A gas amplifier tube comprising; a sealed envelope containing an ionizable medium, means for carrying a load current through the tube comprising a main cathode and a main anode, said anode including portions on either side of and in cooperative spaced relationship with said main cathode, means including an auxiliary cathode for producing an ionizing discharge to provide a conductive plasma between said main cathode and anode, an element interposed between said main and auxiliary cathodes effective for dividing said ionizing discharge thereby to shield said main cathode fro-m the direct effects of said discharge and to direct a divided portion of said discharge into the inter-electrode region on either side of said main cathode, andan electrode interposed between said element and said main cathode adapted for being maintained at a potential effective for attracting the divided portions of said discharge whereby said divided portions are caused to enter said inter-electrode regions on either side of said main cathode adjacent said main cathode and substantially spaced from said main anode.

11. A gas amplifier tube comprising; a sealed envelope containing an ionizable medium, means for carrying a load current through the tube comprising a main cathode and a main anode, said anode including portions on either side of and in cooperative spaced relationship with said main cathode, means including an auxiliary cathode for producing an ionizing discharge to provide a conductive plasma betweensaid main cathode and anode, an element interposed in a direct line path between said cathodes effective for dividing said ionizing discharge thereby to shield said main cathode from the direct effects of said discharge and to direct plasma producing portions of said discharge toward the inter-electrode regions on either side of said main cathode, and an electrode interposed between said element and said main cathode adjacent said main cathode and electrically connected to said main anode, said electrode being adapted for effecting a convergence of the divided portions of said discharge thereby to reduce direct effects of said discharge on said main anode and to direct said portions of said discharge into portions of the inter-electrode regions immediately adjacent said main cathode, said electrode being further effective for serving as an electron collector thereby to add to the load'current of said tube.

12. A gas-filled current amplifying device comprising; a sealed envelope containing an ionizable medium, a main cathode and an anode in cooperative spaced relation defining an inter-electrode region, means for producing an electron discharge to provide a conductive plasma in said inter-electrode region, and discharge-controlling means effective for causing substantially all of the electrons comprising said discharge to pass through said inter-electrode region before impinging upon any portion of said main cathode and anode, thereby to provide maximum utilization of said discharge in producing plasma in said interelectrode region.

13. A gas discharge device comprising; a sealed envelope containing an ionizable medium, a main cathode and anode in cooperative spaced relation Within said envelope, an auxiliary cathode in laterally spaced relation to said main cathode and effective for producing an ionizing discharge between said auxiliary cathode and main cathode and anode to provide a conductive plasma between said main cathode and anode, and a member substantially completely shadowing the portion of said main cathode facing said auxiliary cathode and directing divergent portions of said discharge into regions intermediate said main cathode and anode and on opposite sides of said 10 main cathode, thereby to avoid direct impingement of said ionizing discharge on said main cathode and to provide increased plasma density between said main cathode and anode.

References Cited in the file of this patent UNITED STATES PATENTS 2,578,571 Meier Dec. 11, 1951 2,602,862 Webster July 8, 1952 2,602,906 Johnson July 8, 1952 2,611,880 Webster Sept. 23, 1952 2,660,685 Johnson Nov. 24, 1953 2,687,485 Tirico Aug. 24, 19.54

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