High reliability, long lifetime, negative ion source

1. A negative ion source comprising:

a plasma chamber containing a gas to be ionized;

a microwave source configured to transmit microwaves to the plasma chamber to ionize the gas into atomic species including hyperthermal neutral atoms;

a negative ion source converter configured to convert the hyperthermal neutral atoms to negative ions; and

a magnetic filter configured to reduce the temperature of electrons between the plasma chamber and the negative ion source converter.

2. The negative ion source of claim 1 , wherein the plasma chamber has a high voltage and the microwave source is at ground potential.

3. The negative ion source of claim 1 , further comprising a waveguide configured to electrically isolate the plasma chamber and the microwave source, the waveguide comprising a flange configured to allow a break in the waveguide to be insulated with air.

4. The negative ion source of claim 3 , wherein a plurality of waveguides are used to electrically isolate the plasma chamber and the microwave source.

5. The negative ion source of claim 1 , wherein the gas to be ionized is hydrogen and the hyperthermal neutral atoms produced are hyperthermal neutral hydrogen atoms.

6. The negative ion source of claim 1 , wherein the microwave source comprises a 2.45 GHz microwave source.

7. The negative ion source of claim 1 , wherein the negative ion source converter comprises a cone-shaped cesiated surface.

8. The negative ion source of claim 1 , wherein the magnetic filter comprises a tunable magnetic dipole field provided circumferentially around a junction between the plasma chamber the negative ion converter.

9. A negative ion source comprising:

a plasma chamber containing gas to be ionized;

a microwave source configured to transmit microwaves to the plasma chamber to ionize the gas into atomic species including hyperthermal neutral atoms;

a negative ion converter configured to convert the hyperthermal neutral atoms to negative ions; and

a magnetic filter configured to reduce a temperature of an electron density provided between the plasma chamber and the negative ion converter.

10. The negative ion source of claim 9 , wherein the plasma chamber has a high voltage and the microwave source is at ground potential.

11. The negative ion source of claim 9 , further comprising a waveguide configured to electrically isolate the plasma chamber and the microwave source, the waveguide comprising a flange configured to allow a break in the waveguide to be insulated with air.

12. The negative ion source of claim 11 , wherein a plurality of waveguides are used to electrically isolate the plasma chamber and the microwave source.

13. The negative ion source of claim 9 , wherein the microwave source comprises a 2.45 GHz microwave source.

14. The negative ion source of claim 9 , wherein the negative ion converter comprises a cone-shaped cesiated surface.

15. The negative ion source of claim 9 , wherein the magnetic filter comprises a tunable magnetic dipole field provided circumferentially around a junction between the plasma chamber and the negative ion converter.

16. A method of producing negative ions, the method comprising:

providing a gas to be ionized in a plasma chamber;

transmitting microwaves from a microwave source to the plasma chamber to ionize the gas such that hyperthermal neutral atoms of the gas are produced; and

converting the hyperthermal neutral atoms to negative ions via an interaction with a negative ion source converter.

17. The method of claim 16 , further comprising reducing a temperature of an electron density provided between the plasma chamber and the negative ion source converter with a magnetic filter.

18. The method of claim 16 , further comprising electrically isolating the plasma chamber and the microwave source with a waveguide comprising a flange configured to allow a break in the waveguide to be insulated with air.