Plasma devices

• US 4,584,160 A
• Filed: 09/24/1982
• Issued: 04/22/1986
• Est. Priority Date: 09/30/1981
• Status: Expired due to Fees

• Current Assignee: Tokyo Shibaura Denki Kabushiki Kaisha
• Original Assignee: Tokyo Shibaura Denki Kabushiki Kaisha
• Inventors: Kageyama, Katsuhiro
• Primary Examiner(s): Behrend, Harvey E.
• Application Number:
  US06/423,293
• Time in Patent Office: 1,306 Days
• Field of Search: 376/136, 376/139, 376/140, 376/141
• US Class Current: 376/141
• CPC Class Codes: H05H 1/11 using cusp configuration H05H1/14 takes precedence
• CPC Class Codes: Y02E 30/10 Nuclear fusion reactors

Abstract

Plasma apparatus comprises a vacuum vessel, a device for creating an open-ended magnetic field containing a plasma, a plurality of electrostatic plugs disposed at the open-ended portions of the magnetic field. At least one of the electrostatic plugs comprises a limiter attached to the vacuum vessel, provided with an inner hollow portion and arranged so as to confine the plasma, an anode electrode disposed at the open-ended portion and provided with an inner hollow portion extending along a direction of the open-ended magnetic field, a cathode electrode disposed with space from the anode electrode on the side opposite to the limiter and coaxially with the anode electrode and the limiter, a control electrode passing through a through hole provided for the cathode electrode and extending into the hollow portion of the anode electrode so as to operate to control electrode density thereby to determine the space potential distribution, and electric power applying means so that potentials are applied to the anode electrode, the control electrode, the limiter, and the cathode electrode so as to be higher in the stated order.

Claims

1. In a plasma device of the type comprising a vacuum vessel, means for creating an open-ended magnetic field containing a plasma, and a plurality of electrostatic plugs disposed at open-ended portions of said magnetic field and forming an electric field having a component parallel to the direction of said magnetic field, at least one of said electrostatic plugs including a limiter grounded to said vacuum vessel, provided with an inner hollow portion and arranged so as to control a potential of the space in which said plasma is confined, the improvement in which said electrostatic plug comprises, in addition to said limiter, an anode electrode disposed at an open-ended portion spaced therefrom and provided with an inner hollow portion extending along a direction of said open-ended magnetic field so as to allow all magnetic lines passing through the inner hollow portion of said limiter to pass through said hollow portion of said anode electrode, a cathode electrode spaced from said anode electrode and disposed on a side of said anode electrode opposite to said limiter, said cathode electrode being provided with a through hole, a control electrode disposed so as to pass through the through hole of said cathode electrode and extending into the hollow portion of said anode electrode without contacting with said cathode electrode for controlling electron density thereby to determine the space potential distribution, and means for applying potentials to said anode electrode, said control electrode, said limiter, and said cathode electrode, said potentials being higher in the stated order.

2. The plasma device according to claim 1 wherein the diameter of the inner hollow portion of said anode electrode is substantially equal to the diameter of the inner hollow portion of said limiter and the diameter of said cathode electrode is larger than the inner diameter of said anode electrode.

3. The plasma device according to claim 1 wherein the diameter of the inner hollow portion of said anode electrode is larger than the diameter of the inner hollow portion of said limiter and the diameter of said cathode electrode is larger than the inner diameter of said anode electrode and wherein said through hole of said cathode electrode through which said control electrode extends into the inner hollow portion of said anode electrode is positioned outside of the inner diameter of said limiter.

4. The plasma device according to claim 1, wherein said electrostatic plug further comprises an intermediate electrode disposed between said anode electrode and said limiter and provided with an inner hollow portion coaxial with said anode electrode and said limiter, said intermediate electrode functioning as another cathode electrode.

5. The plasma device according to claim 4 wherein said intermediate electrode comprises an electrode having a negative potential with respect to that of said limiter so that potentials to be applied to said anode electrode, said control electrode, said limiter, said intermediate electrode, and said cathode electrode have higher magnitudes in the stated order.

6. The plasma device according to claim 4 wherein said intermediate electrode comprises an electrode having a positive potential with respect to that of said limiter so that potentials to be applied to said node electrode, said control electrode, said intermediate electrode, said limiter, and said cathode electrode have higher magnitudes in the stated order.

7. The plasma device according to claim 4 wherein said intermediate electrode comprises at least one elemental anode electrode and one elemental cathode electrode arranged alternately in an axial direction thereof and provided with inner through holes coaxial with said anode electrode and said limiter so as to converge from said limiter towards said anode electrode and potentials to be applied to said anode electrode, said control electrode, said limiter, and said cathode electrode have higher magnitudes in the stated order.

8. The plasma device according to claim 1 wherein said electrostatic plug further comprises means for supplying gas into the inner hollow portion of said anode electrode through a further through hole provided for said cathode electrode at a position where a distance between the axis of said hollow portion and said further through hole is larger than a distance between the axis of said control electrode and the axis of said hollow portion.

9. The plasma device according to claim 4 wherein said electrostatic plug further comprises means for supplying gas into the inner hollow portion of said anode electrode through a further through hole provided for said cathode electrode at a position where a distance between the axis of said hollow portion and said further through hole is larger than a distance between the axis of said control electrode and the axis of said hollow portion.