Patent Number: 
Section: claims

1. A neutron generator comprising:a target electrode;a sealed envelope providing an environment for a gas, said sealed envelope defining an ion source chamber bounded by an extraction electrode, said extraction electrode spaced apart from the target electrode;an RF antenna external to said sealed envelope and disposed in proximity to said ion source chamber, said RF antenna for transmitting time-varying electromagnetic fields within said ion source chamber for producing a plasma in said ion source chamber;insulation disposed between said RF antenna and said ion source chamber for electrically insulating said RF antenna from voltages of said ion source chamber and said extraction electrode, the insulation comprising a different material than the sealed envelope;a voltage coupler, wherein the coupler is mounted to the insulation;wherein said extraction electrode operates at a positive voltage potential less than or equal to a steady state potential of the plasma and said target electrode operates at or near ground potential in order to produce an electric field that accelerates ions of said plasma towards said target electrode to induce collisions of ions with target material, thereby causing fusion reactions that generate neutrons; anda plasma electrode disposed within the ion source chamber to influence the steady state potential of the plasma so as to aid extraction of the ions through the extraction electrode;wherein said RF antenna is axially positioned between said extraction electrode and said plasma electrode in relation to an axis formed by the extraction electrode, the plasma electrode, and the target electrode. 2. The neutron generator according to claim 1, wherein:said RF antenna comprises a coil of tubing with coolant flowing therethrough. 3. The neutron generator according to claim 1, wherein:said insulation comprises solid-form voltage insulation surrounding said ion source. 4. The neutron generator according to claim 3, wherein:said solid-form voltage insulation comprises at least one tubular member realized from perfluoroalkoxy. 5. The neutron generator according to claim 3, wherein:said solid-form voltage insulation comprises two or more concentric tubular members realized from perfluoroalkoxy, each having a wall thickness of at least 0.04 inches. 6. The neutron generator according to claim 3, comprising:a first housing that houses said sealed envelope, said RF antenna and said solid-form voltage insulation. 7. The neutron generator according to claim 6, wherein:said solid-form voltage insulation extends between said sealed envelope and said first housing over at least a portion of the lengthwise dimension of said sealed envelope. 8. The neutron generator according to claim 6, wherein:at least one of liquid-form electrically insulating material and gas-form electrically insulating material fill the space between said sealed envelope and said first housing for electrical insulating purposes. 9. The neutron generator according to claim 6, comprising:an RF generator, electrically coupled to said RF antenna, for driving said RF antenna, said RF generator including an RF signal source and an impedance matching network. 10. The neutron generator according to claim 9, wherein:said RF signal generator operates substantially at ground potential and is disposed outside said first housing near said target electrode. 11. The neutron generator according to claim 10, comprising:voltage supply circuit means, electrically coupled to said extraction electrode, for operating said extraction electrode such that it floats at a positive voltage potential. 12. The neutron generator according to claim 11, wherein:said voltage supply circuit means comprises a Cockcroft-Walton voltage multiplier circuit. 13. The neutron generator according to claim 11, wherein:said voltage supply circuit means is disposed within said first housing adjacent or near an end of said sealed envelope opposite said target electrode. 14. The neutron generator according to claim 13, comprising:solid-form voltage insulation, disposed within said first housing and surrounding said voltage supply circuit means, for electrically insulating said voltage supply circuit means. 15. The neutron generator according to claim 14, wherein:said solid-form voltage insulation comprises at least one tubular member realized from perfluoroalkoxy. 16. The neutron generator according to claim 14, wherein:said solid-form voltage insulation comprises at least two concentric tubular members realized from perfluoroalkoxy, each having a wall thickness of at least 0.04 inches. 17. The neutron generator according to claim 14, wherein:said solid-form voltage insulation is part of a unitary member that surrounds said sealed envelope, said unitary member being part of said insulation. 18. The neutron generator according to claim 6, comprising:gas supply means for supplying gas to said enclosed envelope, said gas supply means operating at or near ground potential, said gas supply means disposed near said target electrode. 19. The neutron generator according to claim 11, comprising:control circuitry that interfaces to said voltage supply circuit means, said control circuitry operating at lower voltages than those output by the voltage supply circuit means and disposed outside said first housing. 20. The neutron generator according to claim 19, wherein:said control circuitry and said RF signal generator provide controlled output of ions in a continuous output mode. 21. The neutron generator according to claim 19, wherein:said control circuitry and said RF signal generator provide controlled output of ions in a pulsed output mode. 22. The neutron generator according to claim 21, wherein:said RF signal generator applies pulsed-mode excitation signals to said RF antenna in order to achieve said pulsed output mode. 23. The neutron generator according to claim 21, wherein:said voltage supply circuit means comprises i) DC power supply circuitry floating at positive voltage potentials and ii) circuitry for generating pulsed output signals from output of said DC power supply circuitry and for outputting said pulsed output signals for supply to said extractor electrode. 24. The neutron generator according to claim 23, comprising:an interface to couple control circuitry located outside voltage environment of said voltage supply circuit means to the circuitry for generating pulsed output signals. 25. The neutron generator according to claim 24, wherein:said interface comprises an optical transmitter located outside the voltage environment of said voltage supply circuit means, a fiber optic cable passing through the voltage environment of said voltage supply circuit means and leading to an optical detector located in the voltage environment of said voltage supply circuit means. 26. The neutron generator according to claim 24, wherein:said interface comprises the voltage coupler, wherein the voltage coupler comprises a voltage capacitive coupler, wherein the voltage capacitive coupler is mounted to the insulation. 27. The neutron generator according to claim 1, wherein:said RF antenna comprises a coil of wire or tubing in a helix geometry that surrounds said ion source chamber. 28. The neutron generator according to claim 1, wherein:said RF antenna comprises a coil of wire or tubing in a pancake geometry that is disposed in the vicinity of said ion source chamber. 29. A neutron generator comprising:a target electrode;a sealed envelope providing a pressure environment for a gas, said sealed envelope including an ion source chamber bounded by an extraction electrode, said extraction electrode spaced apart from the target electrode;an RF antenna external to said envelope and disposed in proximity to said ion source chamber, said RF antenna for transmitting time-varying electromagnetic fields within said ion source chamber for producing a plasma in said ion source chamber; anda plasma electrode disposed within the ion source chamber to influence the steady state potential of the plasma so as to aid extraction of the ions through the extraction electrode;wherein said extraction electrode operates at a positive voltage potential with respect to ground potential and said target electrode operates at negative with respect to ground potential in order to produce an electric field gradient that accelerates ions of said plasma towards said target electrode to induce collisions of ions with target material, thereby causing fusion reactions that generate neutrons;insulation disposed between said RF antenna and both said ion source chamber and said extraction electrode, for electrically insulating said RF antenna from voltages of said ion source chamber and said extraction electrode;a voltage capacitive coupler, wherein the coupler is mounted to the insulation; andwherein the RF antenna is axially positioned between said extraction electrode and said plasma electrode in relation to an axis formed by the extraction electrode, the plasma electrode, and the target electrode. 30. The neutron generator according to claim 29,wherein the voltage coupler comprises a voltage capacitive coupler, wherein the voltage capacitive coupler is mounted to the insulation. 31. The neutron generator according to claim 29, wherein:a portion of said sealed envelope defines said ion source chamber, said insulation comprises said portion of said sealed envelope, and said RF antenna is disposed adjacent said portion of said sealed envelope. 32. The neutron generator according to claim 31, wherein:said insulation comprises solid-form voltage insulation surrounding said portion of said sealed envelope. 33. The neutron generator according to claim 32, wherein:said solid-form voltage insulation comprises at least one tubular member realized from perfluoroalkoxy. 34. The neutron generator according to claim 33, wherein:said solid-form voltage insulation comprises two or more concentric tubular members realized from perfluoroalkoxy, each having a wall thickness of at least 0.04 inches. 35. The neutron generator according to claim 33, comprising:a first housing that houses said sealed envelope, said RF antenna and said solid-form voltage insulation. 36. The neutron generator according to claim 35, wherein:said solid-form voltage insulation extends between said sealed envelope and said first housing over at least a portion of the lengthwise dimension of said sealed envelope. 37. The neutron generator according to claim 35, wherein:at least one of liquid-form electrically insulating material and gas-form electrically insulating material fill the space between said sealed envelope and said first housing for insulating purposes. 38. The neutron generator according to claim 35, comprising:an RF generator, electrically coupled to said RF antenna, for driving said RF antenna, said RF generator including an RF signal source and an impedance matching network. 39. The neutron generator according to claim 38, wherein:said RF signal generator operates substantially at ground potential and is disposed outside said first housing near said target electrode. 40. The neutron generator according to claim 39, comprising:first voltage supply circuit means, electrically coupled to said extraction electrode, for operating said extraction electrode such that it floats at a positive voltage potential; andsecond voltage supply circuit means, electrically coupled to said target electrode, for operating said target electrode such that it floats at a negative voltage potential. 41. The neutron generator according to claim 40, wherein:said first and second voltage supply circuit means each comprise a Cockcroft-Walton voltage multiplier circuit. 42. The neutron generator according to claim 40, wherein:said first voltage supply circuit means is disposed within said first housing adjacent or near an end of said sealed envelope opposite said target electrode, and said second voltage supply circuit means is disposed within said first housing adjacent or near said target electrode. 43. The neutron generator according to claim 42, comprising:solid-form voltage insulation, disposed within said first housing and surrounding said first and second voltage supply circuit means, for electrically insulating said first and second voltage supply circuit means. 44. The neutron generator according to claim 43, wherein:said solid-form voltage insulation comprises at least one tubular member realized from perfluoroalkoxy. 45. The neutron generator according to claim 43, wherein:said solid-form voltage insulation comprises at least two concentric tubular members realized from perfluoroalkoxy, each having a wall thickness of at least 0.04 inches. 46. The neutron generator according to claim 43, wherein:said solid-form voltage insulation is part of a unitary member that surrounds said sealed envelope, said unitary member being part of said insulation. 47. The neutron generator according to claim 40, comprising:gas supply means for supplying gas to said enclosed envelope, said gas supply means operably coupled to said first voltage supply circuit means and operating at a positive voltage potential. 48. The neutron generator according to claim 40, comprising:control circuitry that interfaces to said first and second voltage supply circuit means, said control circuitry disposed outside said first housing. 49. The neutron generator according to claim 48, wherein:said control circuitry and said RF signal generator provide controlled output of ions in a continuous output mode. 50. The neutron generator according to claim 48, wherein:said control circuitry and said RF signal generator provide controlled output of ions in a pulsed output mode. 51. The neutron generator according to claim 50, wherein:said RF signal generator applies pulsed-mode excitation signals to said RF antenna in order to achieve said pulsed output mode. 52. The neutron generator according to claim 50, wherein:said voltage supply circuit means comprises i) DC power supply circuitry floating at positive voltage potentials and ii) circuitry for generating pulsed output signals from output of said DC power supply circuitry and for outputting said pulsed output signals for supply to said extractor electrode. 53. The neutron generator according to claim 29, comprising:an electrode disposed between said extraction electrode and said target electrode and operating at or near ground potential.