Ion source utilizing a spherically converging electric field

Claim 1

IN AN APPARATUS FOR PRODUCING ION BEAMS, THE COMBINATION COMPRISING A MEANS OF EMITTING ELECTRONS, AN ACCELERATING GRID, AND A NOZZLE, SAID MEANS OF EMITTING ELECTRONS, SAID ACCELERATING GRID, AND SAID NOZZLE ALL HAVING A COMMON AXIS; A SOURCE OF IONIZABLE MATERIAL IN THE REGION OF SAID ACCELERATING GRID AND SAID NOZZLE; MEANS FOR MAINTAINING APPROXIMATELY THE SAME POTENTIAL ON BOTH NOZZLE AND CATHODE; MEANS FOR MAINTAINING AN APPROXIMATELY SPHERICALLY CONVERGING ELECTROSTATIC FIELD BETWEEN SAID ACCELERATING GRID AND SAID NOZZLE INCLUDING A CURRENT CARRYING COIL OF WIRE WOUND IN A HELIX ABOUT THE SAID COMMON AXIS WITH CONTINUALLY DIMINISHING SPACING BETWEEN TURNS FROM THE END NEAREST THE GRID TO THE END NEAREST THE NOZZLE; AND MEANS FOR MAINTAINING A SUBSTANTIALLY AXIAL MAGNETIC FIELD IN THE REGION BETWEEN SAID ACCELERATING GRID AND SAID NOZZLE SO AS TO PRODUCE PENDULATION OF ELECTRONS IN SAID REGION.