Space Propulsion and Plasmas
Most spacecraft being launched today host both conventional (i.e., chemical) propulsion—used for orbital insertion, large delta-V maneuvers, and attitude control—and electric propulsion (EP)—used primarily for station keeping and, less often, for LEO–GEO transfer and interplanetary missions.
At Penn State, we are conducting research in a number of areas relevant to space propulsion. In the area of chemical propulsion, our experimental research includes characterizing the unsteady combustion behavior of solid and liquid propellant rockets by means of advanced diagnostics. These measurements provide important input into the prediction of rocket-chamber combustion stability.
In advanced space propulsion, we conduct experimental, computational, and analytical research into microwave-heated propulsion, whereby propellant gases are heated to plasma temperatures to obtain performance higher than chemical rockets. Thrusters are characterized under vacuum conditions via direct and indirect thrust measurements and various optical diagnostics.
Advanced propulsion for micro-, nano-, and CubeSats is being pursued with various miniature thrusters being designed and tested. Molecular dynamics (MD) and quantum lattice gas (QLG) simulations are developed of phenomena of interest to space propulsion such as two-phase and plasma flows.
Plasmas are of interest because of their relevance to many advanced space propulsion systems. Other types of plasmas being investigated are low-temperature nonequilibrium, surface-wave, combustion-enhancing, and RF-generated plasmas. We also conduct research in spacecraft–plasma interactions and electrodynamic tethers for energy propulsion, harvesting, and momentum exchange.
Experimental facilities include two 1-meter-diameter vacuum chambers with associated pumping and thrust-measurement equipment. Microwave sources from 2.45 GHz to 20 GHz are available with peak power up 450 kW. Optical and plasma probe diagnostics are used for plasma characterization.
Our experimental facilities also allow for full-scale testing of small spacecraft in a low Earth orbit (LEO)–type environment. The facility is comprised of a vacuum chamber capable of thermal cycling, a plasma source capable of producing streaming ions (1–4 eV) and low-energy electrons (~0.1 eV), and a host of diagnostic tools. Quality assurance tests can be formed at full-scale on 3-U CubeSats (and potentially larger) to assess system or component performance in a realistic plasma environment.