Combined radio frequency and hall effect ion source and plasma accelerator system

• US 20060284562A1
• Filed: 04/27/2006
• Published: 12/21/2006
• Est. Priority Date: 04/27/2005
• Status: Active Grant

• Current Assignee: Busek Co., Inc.
• Original Assignee: Busek Co., Inc.
• Inventors: Brogan, Thomas, Hruby, Vladimir, Hohman, Kurt
• Granted Patent: US 7,420,182 B2
• Time in Patent Office: Days
• US Class Current: 315/111.610
• CPC Class Codes: F03H 1/0075 with an annular channel; Hall-effect thrusters with closed electron drift
• CPC Class Codes: H01J 27/143 Hall-effect ion sources with closed electron drift
• CPC Class Codes: H01J 27/16 using high-frequency excitation, e.g. microwave excitation
• CPC Class Codes: H05H 1/54 Plasma accelerators

Abstract

This invention features a combined radio frequency (RF) and Hall Effect ion source and plasma accelerator system including a plasma accelerator having an anode and a discharge zone, the plasma accelerator for providing plasma discharge. A gas distributor introduces a gas into the plasma accelerator. A cathode emits electrons attracted to the anode for ionizing the gas and neutralizing ion flux emitted from the plasma accelerator. An electrical circuit coupled between the anode and the cathode having a DC power source provides DC voltage. A magnetic circuit structure including a magnetic field source establishes a transverse magnetic field in the plasma accelerator that creates an impedance to the flow of the electrons toward the anode to enhance ionization of the gas to create plasma and which in combination with the electric circuit establishes an axial electric field in the plasma accelerator. An RF power source provides RF power to at least one electrode disposed about and/or inside the plasma accelerator that induces current for ionizing the gas to create the plasma such that the axial electric field accelerates ions through the plasma accelerator to provide ion flux.

Claims

1. A combined radio frequency (RF) and Hall Effect ion source and plasma accelerator system comprising:

a plasma accelerator including an anode and a discharge zone, said plasma accelerator for providing plasma discharge;

a gas distributor for introducing a gas into the plasma accelerator;

a cathode for emitting electrons attracted to the anode and for neutralizing ion flux emitted from the plasma accelerator;

an electrical circuit coupled between the anode and the cathode having a DC power source for providing DC voltage;

a magnetic circuit structure including a magnetic field source for establishing a transverse magnetic field in said plasma accelerator that creates an impedance to the flow of the electrons toward said anode to enhance ionization of the gas to create plasma and which in combination with said electric circuit establishes an axial electric field in said plasma accelerator; and

an RF power source for providing RF power to at least one electrode disposed about and/or inside said plasma accelerator that induces current for ionizing the gas to create the plasma such that said axial electric field accelerates ions through said plasma accelerator to provide ion flux.

2. The system of claim 1 in which the DC voltage provided by the DC power source and RF power provided by the RF power source are adjusted to selectively control the amount of ionization and acceleration of the plasma.

3. The system of claim 1 in which ionization and acceleration of the plasma is optimized by controlling the RF power provided by the RF power source and/or the DC voltage provided by the DC power source.

4. The system of claim 1 in which the DC voltage provided by the DC power source is adjusted to control acceleration of the ions.

5. The system of claim 1 in which the DC voltage provided by the DC power source and the RF power provided by the RF power source are adjusted to decouple ionization of the gas from acceleration of the ions.

6. The system of claim 1 in which the DC voltage generated by the DC power source and RF power provided by RF power source are adjusted to selectively control the energy level of ions and the ion flux density of the plasma.

7. The system of claim 1 in which the RF power source provides RF power that is coupled to the plasma inductively and/or capacitively.

8. The system of claim 1 in which the RF power source provides RF power that is coupled to the plasma by electron cyclotron resonance.

9. The system of claim 1 in which the plasma accelerator includes at least first and second stages wherein first stage is powered by the RF power source and the second stage is powered the DC power source such that most of the ionization occurs in the first stage and most of the acceleration occurs in the second stage.

10. The system of claim 1 in which said at least one electrode includes a coil and/or capacitive plates.

11. The system of claim 1 in which the magnetic circuit structure includes a least one electrically resistive material for minimizing coupling of the RF power into the magnetic circuit structure.

12. The system of claim 1 in which said magnetic circuit structure is segmented to minimize RF power losses.

13. The system of claim 1 in which said magnetic circuit structure includes at least one layer of highly conductive material for minimizing RF power losses.

14. The system of claim 1 in which the axial electric field accelerates the ions in said plasma accelerator to create thrust.

15. The system of claim 1 in which the DC voltage provided by the DC source and the RF power provided by the RF power source are adjusted to increase thrust to the power ratio.

16. The system of claim 1 in which the DC voltage provided by the DC power source and the RF power provided by the RF power source are adjusted to increase specific impulse.

17. The system of claim 1 in which the DC voltage provided by the DC power source and the RF power provided by the RF power source are adjusted to provide a specific impulse of about 1000 seconds at DC voltages of about 100 V DC while delivering a thrust to power ratio of about 0.1N/kW.

18. The system of claim 1 in which the DC voltage provided by the DC power source and the RF power provided by the RF power source are adjusted to provide low to mid energy level ions at high ion flux density.

19. The system of claim 18 in which the low energy ions at said high ionic flux density used to simulate particle flux and energy level of an atmosphere at low altitude orbit.

20. The system of claim 19 in which said atmosphere at low altitude orbit includes low earth orbit atmosphere.

21. The system of claim 20 in which said low earth orbit atmosphere includes atomic oxygen.

22. The system of claim 18 in which the low to mid energy level ions provided at the high ionic flux density are used for semiconductor processing.