Spacecraft charge mitigation is critical for a host of space plasma measurement techniques. However, charge mitigation in tenuous space plasmas can be a difficult problem. It is especially difficult and essential during active experiments that feature ion or electron beams, as collection from the ambient plasma is often insufficient to balance the beam emission current. For electron emission experiments, the use of a plasma contactor that emits an ionized gas is the only practical option. A series of parametric chamber experiments were completed to address how spacecraft charge mitigation using a plasma contactor may scale in tenuous space plasmas. Experiments focus on how spacecraft potential scales with beam emission current, contactor current (the rate at which the contactor generates quasi-neutral plasma), and contactor expellant mass (ion mass). These experimental results are compared to scaling laws derived via Curvilinear Particle-In-Cell (CPIC) simulations for further validation and physical insights. Implications for improving space plasma measurements and enabling future active experiments such as the Connections Explorer (CONNEX) mission are discussed.

Satellites must carry some manner of propulsion system so that course correction or orbit stationkeeping manoeuvres can be carried out. Chemical thrusters have lower specific impulse than electric propulsion systems, and so focus has turned to using plasma and ion propulsion systems such as Hall Effect thrusters and gridded ion thrusters. Both of these systems use gaseous propellants and require a charge neutralisation system, both of which impose certain design compromises. This thesis explores the potential use of pulsed cathodic arcs as a spacecraft propulsion system, determining fuel specific impulse and jet power efficiency of a range of suitable materials over a range of arc currents and pulse durations. Comparisons between element classes are made, so as to identify candidate materials for various mission profiles. The results for magnesium in particular stand out as being comparable to several thruster technologies that are flight-rated.