Electrostatic ion engine having a permanent magnetic circuit

Claim 1

AN ELECTROSTATIC ION ENGINE COMPRISING A CASING FORMING THE PERIPHERAL WALL OF A CHAMBER FOR CONTAINING AN IONIZABLE PROPELLANT, A SOURCE OF SAID PROPELLANT POSITIONED AT ONE END OF SAID CASING, A THERMIONIC EMITTING CATHODE WITHIN SAID CASING FOR BOMBARDING SAID PROPELLANT WITH HIGH VELOCITY ELECTRONS TO FORM IONS, AN APERTURED GRID HAVING A RELATIVELY HIGH NEGATIVE POTENTIAL RELATIVE TO SAID CATHODE POSITIONED AT THE OPPOSITE END OF SAID CASING REMOTE FROM SAID PROPELLANT SUPPLY TO ACCELERATE SAID IONS AWAY FROM SAID ENGINE, A PLURALITY OF PERMENENT MAGNETS POSITIONED AROUND SAID CASING TO FORM A MAGNETIC FIELD ABOUT SAID PROPELLANT AND SAID CATHODE WHEREBY THE PATHS OF SAID HIGH VELOCITY ELECTRONS ARE LENGTHENED TO INCREASE THE RATE OF COLLISION OF SAID ELECTRONS WITH PARTICLES OF SAID PROPELLANT, A PAIR OF SPACED MEMBERS FOR MOUNTING SAID MAGNETS, SAID MEMBERS BEING OF A MAGNETIC PERMEABLE MATERIAL AND IN CONTACT WITH SAID CASING TO FORM THE END WALLS OF SAID CHAMBER, AND MEANS FOR MAINTAINING SAID MEMBERS AND SAID CASING AT THE SAME ELECTRICAL POTENTIAL.