New Design for Reducing Hall Thrusster Chamber Wall Erosion

Web Published:

Princeton Docket # 15-3066-1


Researchers at Princeton Plasma Physics Laboratory, Princeton University, have proposed a new design for extending the lifetime of hall thrusters.


Hall thrusters have been established as a compact and reliable means for satellite applications. Erosion of the surfaces of such thrusters, however, has been a serious factor in limiting their lifetimes. Replacing eroded surfaces by replenishing them is generally unattractive because of the mechanical complexity.


This invention addresses this concern using a lightweight material (liquid lithium) in a porous medium that when heated, draws the lithium to the thruster surface without any mechanical components. Lithium vapor shielding can protect the thruster surfaces from erosion. The ensuing vapor cloud of lithium then allows heat dissipation to occur. The benefit of using lithium as a thruster fuel may further outweigh the cost.



•       Hall thrusters

  o       Satellite

  o       Spacecraft



•       Long lifetime

•       Reduced need for replacement

•       Light-weight


Princeton Plasma Physics Laboratory (PPPL)

The U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) is a collaborative national center for fusion energy research. The Laboratory advances the coupled fields of fusion energy and plasma physics research, and, with collaborators, is developing the scientific understanding and key innovations needed to realize fusion as an energy source for the world. An associated mission is providing the highest quality of scientific education.




Robert Kaita is Head of Boundary Physics Operations on the National Spherical Torus Experiment-Upgrade (NSTX-U) and Co-Principal Investigator on the Lithium Tokamak Experiment (LTX) at the Princeton Plasma Physics Laboratory. He has also done extensive work on the development of a wide variety of diagnostics for high-temperature plasmas. Dr. Kaita is presently focusing on plasma-surface interactions and the use of liquid metals as “first-wall” materials for fusion reactors. In the Graduate Program in Plasma Physics of the Department of Astrophysical Sciences at Princeton University, Dr. Kaita has supervised the research of a large number of doctoral students. He is a fellow of the American Physics Society, and a recipient of the Kaul Prize for Excellence in Plasma Physics Research and Technology Development for pioneering work in the use of liquid lithium metal as a renewable wall for fusion devices.


Michael Jaworski is a staff research physicist at the Princeton Plasma Physics Laboratory (PPPL).  His work focuses on the understanding of fusion energy and the development of new technologies to enable economical power reactors.  He currently leads the Materials and Plasma-Facing Components Topical Science Group in the National Spherical Torus Experiment-Upgrade - a premiere fusion research facility located at PPPL.  Jaworski's research has examined self-generation of fluid flow in liquid metals by thermoelectric magnetohydrodynamic processes; stabilization of free-surface liquids via capillary structures, development of high-power density, liquid-metal targets cooled with supercritical-CO2, and analysis of non-equilibrium effects in fusion plasmas.  Jaworski is also active in the development of molten salts for advanced power plants utilizing direct power extraction from combustion products.  Jaworski received his BS in Mechanical Engineering from the University of Illinois at Urbana-Champaign in 2002.  He received his MS and PhD in Nuclear Engineering from University of Illinois at Urbana-Champaign in 2009.


Intellectual Property & Development status

Patent protection is pending.

Princeton is currently seeking commercial partners for the further development and commercialization of this opportunity.



Michael R. Tyerech

Princeton University Office of Technology Licensing • (609) 258-6762•

Xin (Shane) Peng

Princeton University Office of Technology Licensing • (609) 258-5579•


Patent Information:
For Information, Contact:
Chris Wright
Licensing Associate
Princeton University
Robert Kaita
Michael Jaworski
Igor Kaganovich
Yevgeny Raitses