A Plasmoid Thruster for Space Propulsion

Abstract

There are a number of possible advantages to using accelerated plasmoids for in-space propulsion. A plasmoid is a compact plasma structure with an integral magnetic field. They have been studied extensively in controlled fusion research and are classified according to the relative strength of the poloidal and toroidal magnetic field (B, and Bt, respectively). An object with B, / Bt )' 1 is classified as a Field Reversed Configuration (FRC); if B, = Bt, it is called a Spheromak. The plasmoid thruster operates by producing FRC-like plasmoids and subsequently ejecting them from the device at a high velocity. The plasmoid is formed inside of a single-turn conical theta-pinch coil.As this process is inductive, there are no electrodes. Similar experiments have yielded plasmoid velocities of at least 50 km/s, and calculations indicate that velocities in excess of 100 km/s should be possible. This concept should be capable of producing Isp's in the range of 5,000 -lS,OOO s with thrust densities on the order of lo5 N/m . The current experiment is designed to produce jet powers in the range of 5 -10 kW, although the concept should be scalable to several MW's. The plasmoid mass and velocity will be measured with a variety of diagnostics, including internal and external B-dot probes, flux loops, Langmuir probes, high-speed cameras and a laser interferometer. Also of key importance will be measurements of the efficiency and mass utilization. Simulations of the plasmoid thruster using MOQUI, a time-dependent MHD code, will be carried out concurrently with experimental testing.

Pulse Discharge Network Development for a Heavy Gas Field Reversed Configuration Plasma Device

“…FRCs for space propulsion application have been previously investigated at the University of Washington, University of Alabama-Huntsville, and at the Air Force Research Laboratory (AFRL). [17][18][19][20][21][22][23][24] These studies have mainly focused on lower energy FRC formation and translation with higher atomic mass gases. Specific results from these investigations are described next.…”

“…23,24,26 PTX produces plasmoids in an analogous fashion to that shown in Figure 2; however, a conical geometry is used instead of cylindrical. This geometry has benefits because the FRC creation and acceleration occur within the same step.…”

Magnetic Field Mapping of a Field Reversed Configuration Test Article

“…5 FRCs for space propulsion application have been previously investigated at the University of Washington, University of Alabama-Huntsville, and at the Air Force Research Laboratory (AFRL) at Edwards Air Force Base. [6][7][8][9][10][11][12][13] These studies have mainly focused on lower energy FRC formation and translation with higher atomic mass gases.…”

“…14 Investigations at the University of Alabama-Huntsville and NASA Marshall Space Flight Center have centered on the Plasmoid Thruster Experiment (PTX). 12,13,15,16 PTX produces plasmoids in an analogous fashion to that shown in Fig. 2; however, a conical geometry is used instead of cylindrical.…”

Preliminary findings from efforts to model pulsed inductive theta-pinch plasmas via Particle-In-Cell

“…A number of PIP accelerators have been designed and bench-tested for electric propulsion (EP) applications including the Pulsed Inductive Thruster (PIT) developed by NASA and Northrop Grumman, 1,2,3 the Plasmoid Thruster Experiment (PTX) researched at Univ. of AlabamaHuntsville, 4 the Electrodeless Lorentz Force (ELF) thruster researched by Univ. of Washington, 5 the Experimental Coaxial Field Reversed Configuration Thruster (XOCOT) researched by the Air Force and Univ.…”