CN111180298A - Radio frequency ion source starts filament device - Google Patents
Radio frequency ion source starts filament device Download PDFInfo
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- CN111180298A CN111180298A CN202010086396.1A CN202010086396A CN111180298A CN 111180298 A CN111180298 A CN 111180298A CN 202010086396 A CN202010086396 A CN 202010086396A CN 111180298 A CN111180298 A CN 111180298A
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- cover plate
- molybdenum
- lower flange
- vacuum sealing
- seat
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J27/00—Ion beam tubes
- H01J27/02—Ion sources; Ion guns
- H01J27/16—Ion sources; Ion guns using high-frequency excitation, e.g. microwave excitation
- H01J27/18—Ion sources; Ion guns using high-frequency excitation, e.g. microwave excitation with an applied axial magnetic field
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/46—Generating plasma using applied electromagnetic fields, e.g. high frequency or microwave energy
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/46—Generating plasma using applied electromagnetic fields, e.g. high frequency or microwave energy
- H05H1/4645—Radiofrequency discharges
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- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Electromagnetism (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Electron Sources, Ion Sources (AREA)
Abstract
The invention provides a radio frequency ion source starting filament device which comprises an air inlet pipe, an upper flange insulation pressing plate, an upper flange cover plate, a compression bolt, a lower flange insulation pressing plate, a molybdenum rod, insulation ceramics, a fixed molybdenum seat, a molybdenum seat flange, a vacuum sealing ring, a cooling water pipe and a flange cover plate, wherein the upper flange insulation pressing plate is arranged on the upper flange; the air inlet pipe, the molybdenum seat flange and the molybdenum rod are welded into a whole and are arranged on the lower flange insulating pressing plate, and the whole is arranged on the lower flange cover plate; the upper flange cover plate and the upper flange insulation pressing plate are arranged on the lower flange cover plate through the pressing bolts, and the first vacuum sealing ring, the second vacuum sealing ring and the third vacuum sealing ring are tightly pressed through tightening the pressing bolts to realize vacuum sealing; the insulating ceramic is arranged on the lower flange cover plate through a fixed molybdenum seat; the starting filament device adopts a molybdenum rod as a pulse high-voltage anode, a molybdenum seat as a pulse high-voltage cathode, plasma is established by utilizing high-voltage breakdown ionization, and meanwhile, the starting filament device serves as an air inlet device and is arranged in the middle of the driving cover plate, so that the non-uniformity of plasma discharge is avoided.
Description
Technical Field
The invention relates to the field of radio frequency ion generators, in particular to a filament starting device of a radio frequency ion source.
Background
The Neutral Beam Injection (NBI) system has the characteristics of high heating efficiency and the clearest physical mechanism, and is one of the important auxiliary devices of EAST tokamak. The ion source is a key component in a neutral beam injection system, and a high-power neutral beam injection device necessarily needs to be supported by a high-current ion source. The radio frequency ion source is a commonly used ion source in a neutral injection system, and the typical radio frequency ion source mainly comprises a radio frequency driving power supply, a radio frequency power generator, a transmission cable, a matching circuit, a radio frequency antenna, a discharge chamber, a vacuum system, a cooling system, measurement, control and the like. When the radio frequency ion source works, the radio frequency power supply drives the radio frequency generator to generate radio frequency power, the radio frequency power is transmitted to a radio frequency antenna coil of the ion source discharge chamber through a transmission cable and an impedance matching network, and then the radio frequency power is coupled into the discharge chamber. When radio frequency current passes through the antenna coil, an axial radio frequency magnetic field is generated, the radio frequency magnetic field generates an induction electric field along with the change of time, the induction electric field accelerates electrons, the accelerated electrons collide with gas ions in the discharge chamber to be ionized to generate plasma, and the plasma is maintained.
Considering the resistivity of the shield can, it is difficult for a plasma to be established by rf power alone. In order to make the plasma discharge easier, a starting filament is arranged on the back plate of the discharge chamber. When the air pressure is higher than 1Pa, the starting can be directly realized by inputting radio frequency power. When the air pressure is lower than 1Pa, the lamp can be started by a filament.
At present, the traditional ion source starting filament mostly adopts a structure of a thin tungsten filament (with the diameter of 0.2-0.5 mm) and a vacuum electrode leading-out structure, and the structure has the main defects that:
(1) the thin tungsten filament structure is easy to break when being used repeatedly, and the tungsten filament is easy to become brittle and break when being in a plasma environment for a long time under long pulse.
(2) The radio frequency ion source driving cover plate needs a special interface for installing a fine tungsten wire and vacuum electrode leading-out structure, the available space of the cover plate is small, and a plurality of other interfaces such as diagnosis, a cooling water path, an observation window and the like need to be installed, so that only other equipment interfaces can be occupied.
(3) The filament and vacuum electrode lead-out structure can generally be installed only on one side of the eccentric position, which can cause non-uniformity of plasma discharge.
Disclosure of Invention
The starting filament device aims to overcome the defects that the traditional radio frequency ion source starting filament device is easy to break tungsten filaments after repeated or long-term use, a special interface is needed to be installed to occupy other equipment interfaces, plasma discharge non-uniformity is caused by installation eccentricity, and the like. The invention provides a radio frequency ion source starting filament device which solves the problems that a traditional starting filament is short in service life, needs to be replaced frequently, occupies installation space of other parts, causes uneven plasma discharge due to eccentric installation and the like.
The technical scheme of the invention is as follows: a radio frequency ion source starting filament device comprises an air inlet pipe, an upper flange insulation pressing plate, an upper flange cover plate, a compression bolt, a lower flange insulation pressing plate, a molybdenum rod, insulation ceramics, a fixed molybdenum seat, a molybdenum seat flange, a vacuum seal ring, a cooling water pipe and a flange cover plate;
the air inlet pipe, the molybdenum seat flange and the molybdenum rod are welded into a whole and are arranged on the lower flange insulating pressing plate, and the whole is arranged on the lower flange cover plate; the upper flange cover plate and the upper flange insulation pressing plate are arranged on the lower flange cover plate through the pressing bolts, and the first vacuum sealing ring, the second vacuum sealing ring and the third vacuum sealing ring are tightly pressed through tightening the pressing bolts to realize vacuum sealing; the insulating ceramic is arranged on the lower flange cover plate through a fixed molybdenum seat;
the starting filament device adopts a molybdenum rod as a pulse high-voltage anode and a molybdenum seat as a pulse high-voltage cathode, the high voltage is 5kV-8kV in voltage value range, plasma is established by high-voltage breakdown ionization, and the starting filament device is used as an air inlet device and is arranged in the middle of a driving cover plate, so that the non-uniformity of plasma discharge is avoided.
Furthermore, the anode adopts a metal molybdenum rod with the diameter of 2mm, and the cathode adopts a molybdenum seat with the inner diameter of 4mm, the outer diameter of 10mm, the height of 8mm and the outer side of a threaded structure.
Further, the step of establishing plasma through high-voltage breakdown ionization is that breakdown electric arcs are generated between the bottom of the molybdenum rod and the fixed molybdenum seat through 5kV-8kV pulse high voltage, so that gas is ionized to generate plasma.
Furthermore, a gap exists between the molybdenum rod and the molybdenum seat flange in the filament starting device, and gas can enter the radio frequency ion source discharge chamber through the gap to realize the gas inlet function.
Further, an electric potential is isolated between the molybdenum rod and the lower flange cover plate by adopting insulating ceramic, and the insulating ceramic is arranged on the lower flange cover plate through a fixed molybdenum seat.
Furthermore, the cooling water pipe is cooled by the lower flange cover plate through silver-copper welding, so that the high-temperature plasma is prevented from damaging the lower flange cover plate.
Furthermore, the first vacuum sealing ring is positioned between the upper flange insulation pressing plate and the molybdenum base flange; the second vacuum sealing ring is positioned between the molybdenum seat flange and the lower flange insulating pressing plate; and the third vacuum sealing ring is positioned between the lower flange insulating pressing plate and the lower flange cover plate.
The invention has the beneficial effects that:
(1) the molybdenum rod with the diameter of 2mm and the molybdenum seat are used as high-voltage positive and negative electrodes, and the plasma is established by high-voltage breakdown ionization, so that the structure is more reliable and durable than a thin tungsten wire structure.
(2) The filament device is started and can serve as an air inlet device to realize structure integration optimization, and the space of the radio frequency ion source driving cover plate is saved, so that more space can be provided for the installation of other parts.
(3) The gas inlet device and the starting filament device are integrated and arranged in the middle of the driving cover plate, so that the nonuniformity of plasma discharge is avoided.
Drawings
Fig. 1 is a sectional view of a configuration of an rf ion source start-up filament arrangement.
Description of reference numerals: the vacuum sealing device comprises an air inlet pipe 1, an upper flange insulation pressing plate 2, an upper flange cover plate 3, a lower flange insulation pressing plate 4, a compression bolt 5, a molybdenum rod 6, insulation ceramic 7, a fixed molybdenum seat 8, a first vacuum sealing ring 9, a molybdenum seat flange 10, a second vacuum sealing ring 11, a third vacuum sealing ring 12, a cooling water pipe 13 and a lower flange cover plate 14.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person skilled in the art based on the embodiments of the present invention belong to the protection scope of the present invention without creative efforts.
According to one embodiment of the invention, referring to fig. 1, an air inlet pipe (1), a molybdenum base flange (10) and a molybdenum rod (6) are welded into a whole and are arranged on a lower flange insulating pressing plate (4) and then are arranged on a lower flange cover plate (14) in a whole. The upper flange cover plate (3) and the upper flange insulation pressing plate (2) are installed on the lower flange cover plate (14) through the pressing bolts (5), and the first vacuum sealing ring (9), the second vacuum sealing ring (11) and the third vacuum sealing ring (12) are pressed tightly through tightening the pressing bolts (5) to achieve vacuum sealing. The insulating ceramic (7) is arranged on the lower flange cover plate (14) through a fixed molybdenum seat (8). The first vacuum sealing ring (9) is positioned between the upper flange insulation pressing plate (2) and the molybdenum base flange (10); the second vacuum sealing ring (11) is positioned between the molybdenum seat flange (10) and the lower flange insulation pressing plate (4); and the third vacuum sealing ring (12) is positioned between the lower flange insulating pressing plate (4) and the lower flange cover plate (14).
The upper flange insulation pressing plate (2), the lower flange insulation pressing plate (4) and the insulation ceramic (7) realize potential isolation of the molybdenum rod (6) and the lower flange cover plate (14). When 5kV direct-current high voltage is applied between the air inlet pipe (1) and the lower flange cover plate (14), as the conduction potentials of the molybdenum rod (6) and the air inlet pipe (1) are the same, the conduction potentials of the lower flange cover plate (14) and the fixed molybdenum seat (8) are the same. When gas enters the device through the gas inlet pipe (1), breakdown electric arcs are generated between the bottom of the molybdenum rod (6) and the fixed molybdenum seat (8) due to 5kV pulse high voltage, so that the gas is ionized to generate plasma. The cooling water pipe (13) can cool the lower flange cover plate (14) to prevent the damage of high-temperature plasma. Potential isolation is carried out through the upper flange insulation pressing plate and the lower flange insulation pressing plate and the insulation ceramic, and vacuum sealing is carried out through the compression vacuum sealing ring. When gas enters the device through the gas inlet pipe, breakdown electric arcs can be generated between the bottom of the molybdenum rod and the fixed molybdenum seat due to 5kV pulse high voltage, so that the gas is ionized to generate plasma. The 5kV pulse high voltage can be switched off after the plasma in the discharge chamber is established, and the stable plasma in the discharge chamber is established at the moment. The lower flange cover plate and the fixed molybdenum seat are in direct contact with plasma, but are cooled by water cooling, so that the lower flange cover plate and the fixed molybdenum seat are not damaged. Although the molybdenum rod is in direct contact with the plasma, the melting point of the metal molybdenum is 2620 degrees, the diameter of the molybdenum rod is 2mm, only the tip part of the bottom of the molybdenum rod is in contact with the plasma, and the molybdenum rod cannot be easily damaged, so that the whole structure is safe and reliable and cannot be broken as often as a thin tungsten wire structure.
According to the radio frequency ion source starting filament device provided by the embodiment of the invention, 5kV pulse high voltage is applied between the air inlet pipe and the lower flange cover plate, when gas enters the device through the air inlet pipe, breakdown electric arcs are generated between the bottom of the molybdenum rod and the fixed molybdenum seat due to the 5kV pulse high voltage, so that the gas is ionized to generate plasma. The 5kV pulse high voltage can be switched off after the plasma in the discharge chamber is established, and the stable plasma in the discharge chamber is established at the moment. The device adopts a molybdenum rod with the diameter of 2mm and a molybdenum seat as a high-voltage anode and a high-voltage cathode, and establishes a plasma by high-voltage breakdown ionization, so that the plasma is more reliable and durable than a thin tungsten wire structure; the filament device is started and can serve as an air inlet device to realize structure integration optimization, and the space of the radio frequency ion source driving cover plate is saved, so that more space can be provided for the installation of other parts. The gas inlet device and the starting filament device are integrated and arranged in the middle of the driving cover plate, so that the nonuniformity of plasma discharge is avoided.
Although illustrative embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the embodiments, but various changes may be apparent to those skilled in the art, and it is intended that all inventive concepts utilizing the inventive concepts set forth herein be protected without departing from the spirit and scope of the present invention as defined and limited by the appended claims.
Claims (7)
1. A kind of radio frequency ion source starts the filament device, its characteristic is: the device comprises an air inlet pipe, an upper flange insulation pressing plate, an upper flange cover plate, a compression bolt, a lower flange insulation pressing plate, a molybdenum rod, insulation ceramics, a fixed molybdenum seat, a molybdenum seat flange, a vacuum sealing ring, a cooling water pipe and a flange cover plate;
the air inlet pipe, the molybdenum seat flange and the molybdenum rod are welded into a whole and are arranged on the lower flange insulating pressing plate, and the whole is arranged on the lower flange cover plate; the upper flange cover plate and the upper flange insulation pressing plate are arranged on the lower flange cover plate through the pressing bolts, and the first vacuum sealing ring, the second vacuum sealing ring and the third vacuum sealing ring are tightly pressed through tightening the pressing bolts to realize vacuum sealing; the insulating ceramic is arranged on the lower flange cover plate through a fixed molybdenum seat;
the starting filament device adopts a molybdenum rod as a pulse high-voltage anode and a molybdenum seat as a pulse high-voltage cathode, the high voltage is 5kV-8kV in voltage value range, plasma is established by high-voltage breakdown ionization, and the starting filament device is used as an air inlet device and is arranged in the middle of a driving cover plate, so that the non-uniformity of plasma discharge is avoided.
2. The rf ion source start filament apparatus of claim 1, wherein: the anode adopts a metal molybdenum rod with the diameter of 2mm, and the cathode adopts a molybdenum seat with the inner diameter of 4mm, the outer diameter of 10mm, the height of 8mm and the outer side of a threaded structure.
3. The rf ion source start filament apparatus of claim 1, wherein: the high-voltage breakdown ionization is used for establishing plasma, and the breakdown electric arc is generated between the bottom of the molybdenum rod and the fixed molybdenum seat by adopting 5kV-8kV pulse high voltage so that gas is ionized to generate plasma.
4. The rf ion source start filament apparatus of claim 1, wherein: a gap exists between the molybdenum rod and the molybdenum seat flange in the starting filament device, and gas can enter the radio frequency ion source discharge chamber through the gap to realize the gas inlet function.
5. The rf ion source start filament apparatus of claim 1, wherein: and the molybdenum rod and the lower flange cover plate are isolated from each other by adopting insulating ceramic, and the insulating ceramic is arranged on the lower flange cover plate through a fixed molybdenum seat.
6. The rf ion source start filament apparatus of claim 1, wherein: the cooling water pipe is welded on the lower flange cover plate through silver and copper, and is cooled to prevent high-temperature plasma from damaging the lower flange cover plate.
7. The rf ion source start filament apparatus of claim 1, wherein: the first vacuum sealing ring is positioned between the upper flange insulation pressing plate and the molybdenum seat flange; the second vacuum sealing ring is positioned between the molybdenum seat flange and the lower flange insulating pressing plate; and the third vacuum sealing ring is positioned between the lower flange insulating pressing plate and the lower flange cover plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010086396.1A CN111180298A (en) | 2020-02-11 | 2020-02-11 | Radio frequency ion source starts filament device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010086396.1A CN111180298A (en) | 2020-02-11 | 2020-02-11 | Radio frequency ion source starts filament device |
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| Publication Number | Publication Date |
|---|---|
| CN111180298A true CN111180298A (en) | 2020-05-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010086396.1A Pending CN111180298A (en) | 2020-02-11 | 2020-02-11 | Radio frequency ion source starts filament device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116821565A (en) * | 2023-08-29 | 2023-09-29 | 江苏鹏举半导体设备技术有限公司 | Method for calculating gas ionization critical conditions in radio frequency ion source discharge chamber |
-
2020
- 2020-02-11 CN CN202010086396.1A patent/CN111180298A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116821565A (en) * | 2023-08-29 | 2023-09-29 | 江苏鹏举半导体设备技术有限公司 | Method for calculating gas ionization critical conditions in radio frequency ion source discharge chamber |
| CN116821565B (en) * | 2023-08-29 | 2023-11-07 | 江苏鹏举半导体设备技术有限公司 | Method for calculating gas ionization critical conditions in radio frequency ion source discharge chamber |
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