A HALL PROBE DIAGNOSTIC FOR LOW-DENSITY PLASMA ACCELERATORS

A Hall probe diagnostic was developed for use with plasma thrusters. T he Hall generators were mounted at the end of a stainless steel tube h eat exchanger. Ceramic cement and a Pyrex tube were used as radiation and particle Aux shields, respectively. A thermocouple was used to mon itor the temperature of the Hall generator. The low voltage output fro m the probe was amplified within one meter of the transducer to minimi ze the effect of noise pick up. A National Institute of Standards and Technology traceable Gaussmeter provided an absolute reference for cal ibration, and relative calibrations were performed both in a strong el ectric field and in situ during thruster operation to approximate the conditions in the discharge. The overall accuracy of the diagnostic wa s +/- 6 G . The probes were tested with a Hall-effect thruster, and pr ovided sufficiently accurate data to estimate the magnitude of the clo sed-drift electron current. (C) 1998 American Institute of Physics. [S 0034-6748(98)00306-2]