New Electron Beam Experiments in Space and Active Spacecraft Potential Control

Abstract:

The recent development of relativistic electron accelerators compact enough for space opens a host of exciting new opportunities. For example, an electron beam fired from the Earth’s magnetosphere could be used to trace magnetic field lines in real-time and thus provide closure to long-standing, fundamental questions in magnetosphere-ionosphere coupling. However, electron beam emission in the low-density magnetosphere requires the development of a spacecraft-charging mitigation scheme to ensure safe operation. Currently the most promising spacecraft-charging mitigation scheme is based on the emission of a plasma contactor (high-density plasma) during electron beam operation. Recent work has shown that the contactor can operate in a new regime by emitting substantial ion currents off the plasma contactor surface, thereby opening a new path forward for magnetospheric electron beam experiments.

This presentation summarizes three mission concepts featuring active electron beam emission in the Magnetosphere-Ionosphere Connections Explorer (CONNEX), the Beam-Spacecraft Plasma Interaction and Charging Experiment (B-SPICE), and the Beam Plasma Interaction Experiment (Beam-PIE). These missions promise to answer science questions ranging from what magnetospheric processes drive the aurora (CONNEX) to how ions are emitted from the surface of quasi-neutral plasmas in space (B-SPICE). A summary of recent simulation and ground-based experiments addressing this novel spacecraft-charging mitigation scheme (termed the ion emission model) is also provided in this presentation. Finally, the benefits of a novel spacecraft charging diagnostic currently under development are described in the context of active electron emission experiments in space.