Team Collaboration Diagram

Comprehensive Study of Plasma-Wall Sheath Transport Phenomena

Sponsored by AFOSR, researchers from Georgia Tech (GT) and George Washington University (GWU) are conducting a highly integrated, cumulative research program to develop an understanding of the plasma-wall interaction and how both the sheath and the wall material affect the plasma as a whole. The research seeks to study the most fundamental aspects of mass, charge, and energy transport in the plasma sheath, the relationship between plasma properties and wall surface modification as a function of wall material, and to develop new material design methodologies.

GT High-Power Electric Propulsion Laboratory (HPEPL)

Plasma sheaths are typically extremely thin, with thicknesses commonly in the microns because the electron density is high. Preliminary work physically probed enlarged plasma sheaths produced by a low-density plasma cell. HPEPL's current focus is the development of optical diagnostic techniques, including Thomson scattering and Terahertz time-domain spectroscopy, that can be used to noninvasively investigate plasma sheaths.

GT Materials Modeling (GTMM)

While a Hall Effect thruster operates, the channel walls erode over time as they are exposed to the energetic plasma. The erosion of the channel walls limits the lifespan of hall effect thrusters. Life testing of Hall Effect thrusters is a major undertaking, involving thousands of hours of vacuum chamber time. Because of this, improving modeling of channel wall erosion can allow reduced life testing, and prediction of performance under varying thrust and Isp conditions over the course of a mission. Current erosion models are empirical curve fits to erosion depth over time, or models reduced from certain numerical experiments. They are usually two dimensional, and do not capture certain physics which become apparent during some long qualification life testing. The focus of the current effort is in understanding the physics behind channel wall erosion, including microstructural effects which may seed larger scale erosion variations.

George Washington University (GWU)

  • Development of the multi-scale plasma simulation
  • Sheath simulations in EP environment
  • Plasma-material simulations including sputter yield, SEE, current dependence, energy dependence, angle effect, and temporal behavior of the sputtering process
  • Model validation by direct comparison with experimental data obtained at Georgia Tech