Computational Investigation of the Magnetic Nozzle

Abstract

Particle-in-cell code LSP was used to simulate the development of a plasma plume within a magnetic nozzle under different sets of injection parameters at the throat. Simulations investigated the question of whether the electron population obeyed a polytropic cooling law along the axis of the nozzle. The question of polytropic cooling was approached by extracting and manipulating temperature and density data along the axis of the nozzle and applying a simple linear regression to determine the constant of the polytropic process γ. In all 10 simulations the linear regression analysis yielded coefficients of determination of 0.99 and greater and γ values between 1.3 and 1.5, between the isothermal limit of γ = 1 and the adiabatic limit of γ = 5/3. Variation of magnetic field strength at the nozzle throat from 100 G to 1000 G yielded insignificant indication of a scaling relationship between field strength and effective γ.