Laboratory explorations of energetic electrons in space plasma: results and opportunities

Energetic electrons have dramatic effects in plasmas throughout the universe. Fast electrons make up the super-heated solar corona, produce auroras and radiation belts in planetary magnetospheres, and can damage fusion plasma devices. In response to our growing dependence on the electromagnetic properties of Earth’s space environment, the space plasma physics community has prioritized understanding the dynamics of energetic electrons in these settings. Due to diagnostic limitations, lab experiments have traditionally played a minor role in studying the fundamental plasma physics responsible for energizing electrons. However, recent diagnostic advances have enabled the measurement of electron velocity distributions in lab plasmas with new levels of resolution and precision, resulting in new opportunities to answer long-standing questions. The citation for the 2023 LAD Early Career Award includes lab experiments that settled a decades-old question in space physics by showing that Alfven waves can accelerate electrons that cause auroras. Other investigators performing similar work have detected pitch-angle scattering of energetic electrons by whistler-mode waves and the presence of accelerated electrons produced by magnetic reconnection. These processes are essential for understanding planetary magnetospheres. Ongoing work is exploring electron interactions with whistler-mode waves in an effort to probe the wave-particle interacts credited for many radiation belt phenomena.