Abstract
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.