SPT100 life test with single cathode up to total impulse two million NSEC

The results presented were obtained during life testing of a Stationary Plasma Thruster SPT100. The goal of that test was to achieve the total impulse level 2*10'N»sec operating the thruster with a single cathode. The testing was done at FAKEL and was a followon to the life test of that thruster at JPL where 6141 hours and 6944 cycles were accumulated (5412 hours and 6052 cycles with one cathode). Discharge power was 1350 W during the test (discharge current 4.5 A, discharge voltage 300 V). Parameters of discharge and Xe flow rate were maintained by the facility power and propellant supply subsystems. The test facility equipped with cryogenic Helium pumping system was used for the test. Dynamic pressure in the vacuum tank did not exceed 5.0*10"" torr by Xe. The test included measuring of thrust and total flow rate. SPT operated in cycles from several minutes up to several hundred hours long with single cathode. Stable parameters were demonstrated similar to those obtained during testing at JPL: average thrust 83.9 mN, average specific impulse 1570 sec and average efficiency 0.48. Total operation time was 7515 hours at 6971 cycles. Time of operation with single cathode was 6786 hours at 6079 cycles, total impulse of the thruster amounted to 2.22*10Nsec while total impulse operating with single cathode amounted to 2.01 *10 Nsec. Such cathode life is not its limit. The quantity of emitter material (LaB6) should allow to extend the cathode life by 50%. Both the thruster and the cathode are still operational.