Langmuir Probe Diagnostics of the VASIMR Engine

NASA’s VAriable Specific Impulse Magnetoplasma Rocket Engine (VASIMR) will provide a highly efficient propulsion source that can dramatically reduce Martian transit times, provide for more abort contingencies, and protect astronauts from space radiation with its highly radiation-absorbent hydrogen fuel. The VASIMR is still in its developmental infancy and requires many years of research before its initial operational capability. Much is still unknown about the complex plasma interactions in the exhaust. A Langmuir probe was designed, constructed, and operated to determine current density radial profiles and total particle flux at various stages in the exhaust of VASIMR. The Langmuir probe results proved that the exhaust’s radial profile is Gaussian, experimentally validated predictions of magnetic field line dragging, and verified the ionization efficiency of VASIMR.