In a typical satellite ion thruster, thrust is created by accelerating positive ions through a series of gridded electrodes at one end of a thrust chamber. The electrodes, known as an ion extraction assembly, create thousands of tiny beams of thrust. The beams are prevented from being electrically attracted back to the thruster by an external electron-emitting neutralizer. The power processing unit (PPU) is the device which serves to provide electrical control and power to drive the ion thruster, including control of the emission current in the neutralizer cathode.
FIG. 1 is a schematic diagram of a power processor system 100 operating with two individual power processor units 102A, 102B (collectively referred to as 102), one for each ion thruster 104A, 104B (collectively referred to as 104) of acathode heater to heat it to a high temperature at startup and initiate electron emission for gas ionization and a keeper supply 116A, 116B (collectively referred to as 116) coupled to the discharge keeper to maintain electron emission for ionization after startup. The accelerator supply 118A, 118B (collectively referred to as 118) accelerates ions out of the thruster body 106A, 106B.
The PPU 102A, 102B also includes similar power supplies to drive the neutralizer 108A, 108B which serves to both charge neutralize and current neutralize the ion beam. The neutralizer heater supply 120A, 120B (collectively referred to as 120), coupled to the neutralizer cathode heater, heats it to initiate electron emission from the neutralizer. The neutralizer keeper supply 122A, 122B (collectively referred to as 122) maintains electron emission after