Xenon Hall Thrusters

Plasma thrusters are famous for their fuel efficiency: when compared with a chemical rocket, a typical plasma thruster may only require 1/10th the amount of propellant to accomplish a given mission. However, because the electric power available on a spacecraft is limited to a few 10’s of kW, plasma thrusters are limited in the amount of instantaneous thrust they can provide. The result is that, while a plasma thruster requires less fuel, it will take longer to accomplish a given mission than a high-thrust chemical system. For certain missions, it is more important to get the spacecraft to its destination in a short time than it is to conserve propellant. These types of missions require more thrust than is currently available using state-of-the-art Hall thrusters.

Work at the Isp Lab is focusing on increasing the amount of thrust available from a Hall thruster for a given input electric power. These so-called High Thrust-to-Power ratio devices would be an enabling technology for many missions, civilian as well as military, requiring rapid re-positioning of space assets. Researchers are examining the various thrust and power loss mechanisms of current Hall thrusters with the intention of identifying means of improvement. A subtle, but critical, related area of research involves understanding the coupling voltage between the thermionic hollow-cathode/neutralizer and the thruster plasma.