Three-Dimensional Modeling of Magnetic Nozzle Processes

摘要

Simulations of plasma flow through a magnetic nozzle were conducted using the time-dependent, three-ndimensional magnetohydrodynamics code MACH3. Modeling of magnetic nozzle flow using constant, classicalnisotropic, and classical tensor resistivity provides preliminary quantitative depiction of the core-plasma flow,nevolution of themagnetic field, and conversion of stagnation enthalpy to directed exhaust thrust energy, and serves asnverification for the numericalmodel. For stagnation conditions of 100 eVand 0.355MPa, steady-statemodeling usingnheliumpropellant demonstrates a nearly isentropic expansion through the nozzle to exhaust speeds near 160 = .nThe extent of the contribution from the magnetic diffusion and the mass-flux penetration to the thickness of thencurrent layer strongly depends on plasma resistivity. Plasma-field interaction results in a reduction of approximatelyn50%of the directed axial thrust when comparedwith a solid-wall nozzle of equivalentMach number design. At fixednplasma pressure and applied field the exhaust velocity scales appropriately as the square root of the stagnationntemperature.