DIAGNOSIS OF PERFORMANCE OF ELECTRIC PROPULSION ENGINES

A program of research has been carried out on the response of electron emissive particle beam systems to electric fields. These 'E-field meters' may be used in turn for determinations of the surface electric field strength of isolated spacecraft. The experimental and analytical studies have resulted in the development of a comparatively sensitive device capable of electric field strength measurements within approximately a .1 volt/cm with an extended range capability up to electric field strengths of 100 volts/cm at reduced sensitivities. The meter performance is adequate for its operation in the space environment where the factors of the geo-magnetic field and the ambient space plasma and photo-electric effects, though present, constitute only minimum perturbations to the meter performance. Although effort remains to be done in the transformation of this laboratory type field sensor into a fully operational spacecraft instrument, the present program of research has successfully examined and determined the basic questions of scientific merit for this device. (Author)