Patent ID: 6208080
Filing Date: 2001-03-27
Classification: F03H

Abstract:
An ion accelerator with closed electron drift having an annular gas discharge area including an exit end, discharge of gas through the exit end defining a downstream direction, said accelerator comprising:an inner magnetic pole located at the inside of and encircled by the annular gas discharge area adjacent to the exit end;an outer magnetic pole located at the outside of and encircling the annular gas discharge area adjacent to the exit end;a magnetic field source for producing a generally radially extending magnetic field between the inner pole and the outer pole in the vicinity of the exit end of the gas discharge area;an anode located upstream of the exit end of the gas discharge area;a gas source for supplying an ionizable gas to the gas discharge area for flow in a downstream direction toward the exit end;an electron source for supplying free electrons for introduction toward the exit end of the gas discharge area in a generally upstream direction;an electric field source for producing an electric field extending from the anode in a downstream direction through the exit end, interaction between the ionizable gas from the gas source and free electrons from the electron source producing ions accelerated in a downstream direction by the electric field to produce a propelling reaction force; anda magnetic flux bypass component for shaping the magnetic field in the area of the exit end of the gas discharge area, said component comprising:a downstream inner ring of magnetically permeable material located at the inside of and encircled by the annular gas discharge area adjacent to the exit end;an upstream inner ring of magnetically permeable material located at the inside of and encircled by the annular gas discharge area at a location a substantial distance upstream from the downstream inner ring;an inner quantity of magnetically permeable material magnetically coupling the downstream inner ring and the upstream inner ring;a downstream outer ring of magnetically permeable material located at the outside of and encircling the annular discharge area adjacent to the exit end;an upstream outer ring of magnetically permeable material located outside of and encircling the annular gas discharge area at a location a substantial distance upstream from the downstream outer ring;an outer quantity of magnetically permeable material magnetically coupling the downstream outer ring and the upstream outer ring; andan upstream quantity of magnetically permeable material coupling the upstream inner ring and the upstream outer ring to form a continuous magnetic path from the downstream inner ring through the inner quantity of magnetically permeable material to the upstream inner ring, through the upstream quantity of magnetically permeable material to the upstream outer ring, and through the outer quantity of magnetically permeable material to the downstream outer ring, at least one of said quantities of magnetic material having openings therethrough for regulating the reluctance of the magnetic path to control the shape of the magnetic field in the vicinity of the exit end of the gas discharge area.