ION Emission Energetics From a Positively Biased Hollow Cathode Contactor

A mission concept is under development which involves firing a spacecraft-mounted electron beam from Earth's magnetosphere to connect distant magnetic field lines in real time [1]. To prevent excessive spacecraft charging and consequent beam return, the spacecraft must be neutralized in the tenuous plasma environment of the magnetosphere. Particle-In-Cell (PIC) simulations suggest neutralization can be accomplished by emitting a neutral plasma with the electron beam. Interpretation of these simulations also led to an ion emission model in which ion current is emitted from a quasineutral plasma as defined by the space charge limit [2], [3].