1. demonstrated over 11,600 ignitions. For this test program, a test profile was developed to allow accelerated cyclic testing at projected operating conditions. To datc, two HCAs have successfully demonstrated multiple ignitions at conditions similar to those expected on-orbit. A prototype HCA has achieved 3598 successful ignitions. Nominal operating conditions were 18.0 v and 8.82pa.Lls for anode voltage and xenon flow rate, respectively. The anode voltage from an initial value of 12.8V,i the ignition testing, several parameters were investigated, of which the heater power and pre-heat time were the sept,1993,
2. AIAA Paper 94-3312, June 1994,