Electron flow accelerating method and apparatus which can generate a high-power beam

• US 5,677,597 A
• Filed: 03/13/1996
• Issued: 10/14/1997
• Est. Priority Date: 12/21/1993
• Status: Expired due to Fees

• Current Assignee: Sumitomo Heavy Industries Limited
• Original Assignee: Sumitomo Heavy Industries Limited
• Inventors: Tanaka, Masaru
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): SHINGLETON, MICHAEL B
• Application Number:
  US08/614,884
• Time in Patent Office: 580 Days
• Field of Search: 315/111.21, 315/111.31, 315/111.41, 315/111.51, 315/111.61, 315/111.71, 315/111.81, 250/492.3, 250/492.1, 250/396 R
• US Class Current: 315/111.21
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32623 Mechanical discharge control means
• CPC Class Codes: H01J 37/3266 Magnetic control means
• CPC Class Codes: H01J 37/32688 Multi-cusp fields
• CPC Class Codes: H05H 1/54 Plasma accelerators

Abstract

In a plasm beam generating apparatus comprising a plasma source and an anode portion for receiving a plasma beam, a magnetic field generating device is arranged between the plasma source and the anode portion along an orbit of the plasma beam to generate magnetic field having magnetic gradient such that space charges are generated. The magnetic field generating device accelerates electron flow in the plasma beam to supply accelerated electron flow to the anode portion.

Claims

1. A method of accelerating electron flow within a plasma beam along an orbit of said plasma beam, in which an anode portion is arranged within a chamber provided with a plasma source to generate said plasma beam from said plasma source towards said anode portion, comprising the steps of:

generating a cusp-shaped magnetic field on the orbit of said plasma beam by annular-shaped magnetic field generating means arranged so as to surround the orbit of said plasma beam;

generating a plasmatic state within said cusp-shaped magnetic field, wherein an electron density of said plasma beam is higher than an ion density, to thereby increase a discharge voltage in the plasmatic state; and

passing the electron flow in said plasma beam through a point cusp of said cusp-shaped magnetic field to thereby accelerate said electron flow.

3. A method of accelerating electron flow within a plasma beam as recited in claim 1;

wherein said cusp-shaped magnetic field is generated using an annular-shaped permanent magnet.

4. A method of accelerating electron flow within a plasma beam as recited in claim 1, wherein said annular-shaped magnetic field generating means includes two electromagnetic coils arranged along the orbit of said plasma beam, one of said two electromagnetic coils being closer to said anode portion and having a diameter smaller than that of another one of said two electromagnetic coils, said method further including a step of:

supplying the two electromagnetic coils with electric currents which are different, in polarity, from each other.

5. A method of accelerating electron flow within a plasma beam as recited in claim 1, further comprising a step of:

contacting said plasma beam with an electrode located between said annular-shaped magnetic field generating means and said plasma source, said electrode being supplied with a bias potential, so that the electron density of said plasma beam is varied to thereby control said discharge voltage.

6. A method of accelerating electron flow within a plasma beam as recited in claim 3, further comprising a step of:

contacting said plasma beam with an electrode located between said annular-shaped magnetic field generating means and said plasma source, said electrode being supplied with a bias potential, so that the electron density of said plasma beam is varied to thereby control said discharge voltage.

7. A method of accelerating electron flow within a plasma beam as recited in claim 4, further comprising a step of:

contacting said plasma beam with an electrode located between said annular-shaped magnetic field generating means and said plasma source, said electrode being supplied with a bias potential, so that the electron density of said plasma beam is varied to thereby control said discharge voltage.

2. An apparatus for accelerating electron flow within a plasma beam, comprising:

a chamber for defining a discharge space;

a plasma source mounted on said chamber to generate a plasma beam;

an anode portion arranged within said chamber so as to receive said plasma beam; and

annular-shaped magnetic field generating means arranged within said chamber for surrounding an orbit of said plasma beam and for generating a cusp-shaped magnetic field along the orbit of said plasma beam, said anode portion being arranged on an extension of a point cusp of said cusp-shaped magnetic field, electron flow in said plasma beam being passed through the point cusp of said cusp-shaped magnetic field to thereby accelerate said electron flow to supply the accelerated electron flow to said anode portion.

8. An apparatus for accelerating electron flow within a plasma beam as recited in claim 2, wherein said annular-shaped magnetic field generating means comprises:

a first annular-shaped permanent magnet.

9. An apparatus for accelerating electron flow within a plasma beam as recited in claim 2, wherein said annular-shaped magnetic field generating means comprises:

two electromagnetic coils arranged along the orbit of said plasma beam, one of said two electromagnetic coils being closer to said anode portion and having a diameter smaller than that of another one of said two electromagnetic coils, said two electromagnetic coils being supplied with electric currents which are different, in polarity, from each other.

10. An apparatus for accelerating electron flow within a plasma beam as recited in claim 2, further comprising:

an electrode located between said annular-shaped magnetic field generating means and said plasma source so as to be brought into contact with said plasma beam for controlling a discharge voltage; and

a power supply for supplying a predetermined bias potential to said electrode.

11. An apparatus for accelerating electron flow within a plasma beam as recited in claim 9, further comprising:

an electrode located between said annular-shaped magnetic field generating means and said plasma source so as to be brought into contact with said plasma beam for controlling a discharge voltage; and

a power supply for supplying a predetermined bias potential to said electrode.