Investigating Space-Based Plasma Wave Generation Using a Mod-Anode Electron Gun for Future Space Missions*

The Beam Plasma Interactions Experiment (Beam-PIE) was a NASA sounding rocket experiment that launched in November 2023 using space as a laboratory to explore wave generation from a modulated electron beam in the ionosphere. Beam-PIE provided valuable experimental data to enhance our understanding of beam-plasma-wave interactions in the space environment. Ongoing analysis of these results is expected to yield further insights into controlled beam-plasma interactions, with potential applications in space-based communication and radiation belt remediation systems.

A critical challenge of electron gun design is ensuring mechanical and electrical durability, where traditional components, including grids, often fail when subjected to the high levels of mechanical vibrations associated with a space experiment. An alternative less complex approach involves using a mod-anode, a second anode placed between the cathode and the main anode. This mod-anode can efficiently turn the electron beam on and off with lower current and voltage requirements than a bare electron gun, while offering superior mechanical durability compared to traditional designs. However, the voltage required for a mod-anode design to turn the electron beam on and off is much larger than the required voltage of a grid. To address these challenges, we are developing analytical and numerical models of mod-anode designs using CST Microwave Studio. These models will be used to optimize the performance of mod-anode electron guns for future experiments. A new particle accelerator, for Beam2PIE, is being designed to incorporate a mod-anode electron gun modification. This design is anticipated to enhance the reliability and effectiveness of beam generation in space-based experiments.

This study presents the preliminary theoretical predictions, an outline of the new accelerator design, and the initial experimental results from Beam-PIE. The insights gained from this research will contribute to advancing our understanding of beam-plasma interactions and improving the design of electron guns for future space missions.