Two-dimensional Model Of Stationary Plasma Thruster

Abstract

A stationary plasma thruster (SPT) is an electromagnetic thruster design which has been developed primarily in the Former Soviet Union and which has properties which make it especially suitable for applications such as satellite station-keeping. The device geometry is cylindrical with a central dielectric rod and dielectric walls. A voltage (a few 100 V) is maintained between the anode (at one end of the cylinder) and the cathode (usually a hollow cathode or a filament slightly past the other end of the cylinder), and the current flowing through the device is on the order of several amps. Gas (usually xenon) flows in from the anode and is ionized by the electrons which are emitted from the cathode. An external magnetic field is applied primarily in the radial direction with a magnetic strength such that the electron gyroradius is much less than the device dimension but that the ion gyroradius is larger than the device dimensions. The SPT is a particular type of closed-drift thruster where ions are electrostatically accelerated in the thrust direction, with the accelerating electric field established by an electron current interacting with a transverse magnetic field. In such a configuration, an ion flux is produced with amore » high efficiency. The authors have developed a two-dimensional model for the purpose of elucidating the physical phenomena controlling the device performance and eventually developing scaling laws to guide the optimization of SPT`s. The model consists of fluid equations for the electrons and ions coupled to Poisson`s equation for the self-consistent electric field. The description of ion transport can be improved if necessary by solving the Vlasov equation with a particle method. Electron diffusion across the magnetic field is an important aspect of closed-drift thruster operation.« less