Numerical and Experimental Investigation of the

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Numerical and Experimental Investigation of the Current Distribution in Self-Field Magnetoplasmadynamic Thruster s Jorg Heiermann* and Monika Auweter-Kurtz"' Universitat Stuttgart. 70550 Stuttgart. Germany The plasma flow in magnetoplasmadyn amic (MPD) self-field thrusters is described by consenation equations for heayy particles, turbulence. electrons, and the magnetic field for reaction and thermal nonequilibrium. The equations are discretized on unstructured adaptive meshes. The numerical results, which are verified by experimental data. show that the newi)' developed finite volume code predicts the thrust well. It is found that electron pressure diffusion drives the arc out of nozzle-type MPD thrnsters. The drop of density in front of a water-cooled anode is the reason for the beginning of thruster instabilities at high electric currents.

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magnetic field. T turbulent closure coefficient speed of sound. ms- 1 electric field, vm- 1 enen:v densitv. Jm- 3 cons~~nt 1.60219 x 10- 19 A. s flux. m- 2 s- 1 force. N near-wall function momentum flux. Nm- 2 enencv flux. wm- 2 splitd~g quantity. ms- 1

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current. A diffusion flux. m- 2 s- 1 electric current density. Am-=' reaction rate. m3 s- 1 23 J. K-1 constant 1.38062 X constant 6.63349 x l0- 26 kg ~ mass flux. kg s- 1 particle density. m- 3 turbulent production term. m2 s- 3 pressure. Pa source term. Nm- 3 and \Vm- 3 velocity, ms- 1 turbulent conservation quantity, m2 s- 1 radial coordinate, m reference velocity. ms- 1 temperature. K time~ s volta2:e. V velocity. ms- 1 charge number axial coordinate. m parameter ener2:v transfer coefficient. wm