Claims
- 1. A plasma generating device for use as a source of ions while operating at high vacuum and at high voltage relative to an ion extracting system, comprising:
- a gun comprising a body having an outer diameter section and having a cylindrical cavity connected to a source of plasma-forming gas, a cylindrical cathode member mounted coaxially in the cylindrical cavity, and a nozzle anode affixed to the body in coaxial, plasma-forming relationship with the cathode member and the cylindrical cavity; and
- a mounting structure generally encircling the gun, comprising a mating flange adapted for vacuum sealing connection to an ion extracting system in electrical contact therewith, a metallic ring welded to the outer diameter section of the body and extending forward therefrom, a ceramic ring brazed to the first metallic ring and extending forward therefrom, and a second metallic ring situated between the ceramic ring and the mating flange, the second metallic ring being brazed to the ceramic ring and welded to the mating flange, such that the mounting structure supports the gun in vacuum relationship with and in electrical isolation from the ion extracting system.
- 2. A plasma generating device according to claim 1 wherein:
- the gun further comprises an intermediate electrode mounted therein having an orifice located coaxially between the cathode member and the nozzle anode and having an elongated cylindrical middle section surrounding a substantial portion of the cathode member, a ring shaped magnetic coil located generally outward of the intermediate electrode and outward of and proximate to the mounting structure, and a partial shell on the magnet coil having portions on the outer, forward and rear sides of the coil;
- the nozzle anode comprises an outer rim located proximate to the ceramic ring; and
- the intermediate electrode, the nozzle anode, the shell portions and the section of gun body inward of the rear portion of the shell are formed substantially of material having high magnetic permeability such that a generally toroidal shaped magnetic field loop about the electrically energized coil traverses the gun body, the intermediate electrode, the nozzle anode and the ceramic ring to aid in focusing the plasma.
- 3. A plasma generating device according to claim 1, further comprising an inlet conduit for conveying gas at near-vacuum pressure extending between an external gas source and the cylindrical cavity of the gun body without gaseous discharge occurring in the conduit, an electrically insulating container coupled into the conduit to form a portion thereof, a multiplicity of electrically insulating pellets in a plurality of layers filling the cross-section of the container, and retention means disposed at opposite ends of the container having a multiplicity of orifices therein to retain the pellets while readily conveying the gas therethrough.
- 4. A conduit according to claim 3 wherein the pellets substantially fill the container and are packed sufficiently to prevent electrical discharge and to render insignificant resistance to gas conveyance.
- 5. A conduit according to claim 4 wherein the pellets are generally spherical in shape have similar in diameters.
- 6. A conduit according to claim 5 wherein the pellet diameters are between about 1 mm and about 5 mm.
- 7. A conduit according to claim 4 wherein the container is tubular in shape and has a ratio of length to inner diameter between about 1 and about 10.
- 8. A plasma generating device according to claim 3 further comprising a housing within which the gun is mounted, the housing being electrically isolated from the gun, wherein the container is situated within the housing.
- 9. A plasma generating device according to claim 1, further comprising:
- a plurality of anode cooling fins disposed externally to the gun in heat conducting relationship with the nozzle anode;
- a housing generally enclosing the gun having an effluent opening for the plasma, an inlet opening for the cooling air and an outlet opening for the cooling air; and
- a fan mounted in the housing with respect to the gun so as to cause cooling air to flow in a path over the cooling fins.
- 10. A plasma generating device according to claim 9 further comprising a plurality of additional cooling fins disposed in heat conducting relationship with the cathode member in the path of the cooling air flow.
- 11. A plasma generating device according to claim 10 wherein a heat conducting rod extends from the cathode member rearward through the body, and the additional cooling fins are attached to the heat conducting rod.
- 12. A plasma generating device according to claim 9, further comprising an intermediate electrode mounted in heat conducting relationship with the body, having an axial orifice therein located coaxially between the cathode member and the nozzle anode, the nozzle anode being in heat conducting relationship with the body, and the plurality of anode cooling fins being attached to the external surface of the body.
- 13. A plasma generating device according to claim 9 further comprising:
- a rim on the body located radially outward from the cathode member;
- a generally tubular intermediate electrode mounted in the gun, having a rear section and a forward end with an axial orifice therein positioned coaxially between the cathode member and the nozzle anode, the rear section being attached to the rim of the body in heat conducting relationship therewith, the body having an external surface with the anode cooling fins attached thereto;
- a tubular support member surrounding the forward end of the intermediate electrode and attached circumferentially between the nozzle anode and the rim of the body to support the nozzle anode and conduct heat therefrom; and
- an annular insert of heat-conducting electrical insulator material interposed between the tubular support member and the rim of the body to electrically isolate the nozzle anode from the intermediate electrode.
- 14. The plasma generating device of claim 3 wherein the external gas source comprises a piezoelectric crystal leak valve, a conduit for the plasma-forming gas connected between the leak valve and the cylindrical cavity, and a pressure sensor having a signal voltage output and being situated to detect the pressure of the plasma-forming gas at a point between the leak valve and the nozzle anode, and means for applying the signal voltage to the piezoelectric crystal to regulate gas flow through the leak valve in inverse proportion to changes in the pressure.
- 15. A conduit for conveying gas at low pressure between an external source of gas and a device maintained at high voltage relative to the external gas source without gaseous discharge occurring in the conduit, said conduit extending from the external gas source to the device and comprising an electrically insulating container, a multiplicity of electrically insulating pellets in a multiplicity of layers filling the cross-section of the container, and retention means disposed at opposite ends of the container having a multiplicity of orifices therein to retain the pellets while readily conveying the gas therethrough, the pellets being packed with their adjacent surfaces separated by maximum distances that are less than the average path length of electrons and ions in a low pressure gas in the conduit such as to prevent electrical discharge in the gas.
- 16. A conduit according to claim 15 wherein the pellets substantially fill the container and are packed sufficiently and to rendor insignificant resistance to gas conveyance.
- 17. A conduit according to claim 16 wherein the pellets are generally spherical in shape and similar in diameter.
- 18. A conduit according to claim 17 wherein the pellet diameters are between about 1 mm and about 5 mm.
- 19. A conduit according to claim 16 wherein the container is tubular in shape and has a ratio of length to inner diameter between about 1 and about 10.
Parent Case Info
This application is a continuation of co-pending application Ser. No. 664,195 filed Oct. 24, 1984 now abandoned.
US Referenced Citations (6)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0102392 |
Aug 1981 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
664195 |
Oct 1984 |
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