Electron-beam/plasma coupling physics in support of active experiments in space

The recent development of compact, relativistic electron accelerators [1] might open up a new era of active experiments in space, driven by important scientific and national security applications [2] . Examples include using electron beams to trace magnetic field lines and establish causality between physical processes occurring in the magnetosphere and those in the ionosphere [2] . Another example is the use of electron beams to trigger waves in the near-Earth environment [3] . Waves could induce pitch-angle scattering and precipitation of energetic electrons, acting as an effective radiation belt remediation scheme.