Investigation of Propulsive Plasma Flows Using Numerical Simulations

Research supported by:

NASA-JPL's Advanced Propulsion Group
PPPL's Program in Plasma Science and Technology
DOE Compuational Science Graduate Fellowship

Introduction

A major obstacle to the use of magnetoplasmadynamic thrusters (MPDT) on spacecrafts, is their low efficiency. For an electric propulsion system to be efficient, the electrical power deposited into the plasma ought to be converted to directed electromagnetic kinetic power and directed electrothermal kinetic power. However, the energy invested is expended among many other sinks, such as undirected electromagnetic and electrothermal kinetic power, electrode losses, plasma thermal losses, internal mode losses, and radiation, that are wasteful for the purpose of propulsion.

Given the dearth of high power test facilities, simulations can be valuable aides to research by reducing the need for expensive, and sometimes unviable, experimental parametric studies.

The goals of this work are:

  • To develop and validate a numerical solver with advanced features specific to the purpose of simulating propulsive plasma flows
  • Apply this solver to understand the role of physical processes, that may not be tractable by experimental investigations alone
  • Use the results from simulation as an aide/guide to experimental research on gas-fed Magnetoplasmadynamic Thrusters (MPDT) and Lithium Lorentz Force Accelerators (Li-LFA)

    Description

    Numerical Scheme:

  • Conservative form finite volume scheme,
  • Generalized non-orthogonal quadrilateral grid,
  • Fractional splitting for diffusive fluxes and source terms.

    Physical Models:

  • Full set of MHD equations, with classical resistivity, electron and ion thermal conduction, Hall effect and gradient drifts,
  • Thermal nonequilibrium between electrons and ions,
  • Real equation of state,
  • Anomalous transport,
  • Multi-level equilibrium ionization.

    Recent Accomplishments

    Computational Methods

  • For parallel computing we utilize the Beowulf Cluster at the Princeton Plasma Physics Laboratory.
  • Recent versions of the code employ a restructured parallel architecture which, together with a new domain decomposition routine, has led to a dramatic improvement in the parallel efficiency.

    Physical Processes

  • Our simulation correctly predicts many of the salient features of the discharge that were observed in experiments.

    Calculated values for electron density (left) are compared with photograhed light emission from the discharge of the Full-Scale Benchmark thruster (for argon flowing at 6.0g/s and 16.0kA discharge current).

    Calculated contours of electron temperature in the Full-Scale Benchmark Thruster(for argon flowing at 6.0g/s and 16.0kA discharge current).


    Relevant Publications

  • Comparison of Simulated Plasma Flowfields to Experimental Measurements for a Gas-Fed Magnetoplasmadynamic Thruster , Proceedings of the 39th Joint Propulsion Conference, Huntsville, AL, 2003.
  • Development and Validation of a Parallel MHD Code for the Simulation of Self-Field MPDT Flows , Proceedings of the 27th International Electric Propulsion Conference, Pasadena, CA, 2001.
  • A Flux-Limited Numerical Method for the MHD Equations to Simulate Propulsive Plasma Flows, International Journal for Numerical Methods in Enginnering, v.53:1415-1432, 2002.
  • Simulation of MPD Flows Using a Flux-Limited Numerical Method for the MHD Equations, M.S. Thesis, Princeton University, October 2000.
  • Application of a New Numerical Solver to the Simulation of MPD Flows, Proceedings of the 36th Joint Propulsion Conference, Huntsville, AL, 2000.
  • A Flux-Limited Numerical Method for the MHD Equations to Simulate Propulsive Plasma Flows, Proceedings of the 31st Plasmadynamics and Lasers Conference, Denver, CO, 2000.
  • An Accurate Characteristics-Splitting Scheme for Numerical Solution of MHD Equations, Proceedings of the 26th International Electric Propulsion Conference, Litakyushu, Japan, 1999.

    Other:

  • A Survey of Propulsion Options for Cargo and Piloted Missions to Mars , Proceedings of the 1st International Conference on New Trends in Astrodynamics, College Park, MD, 2003.

    Contact

    Peter Norgaard

    Kamesh Sankaran