Plume Model of Hall Effect Plasma Thrusters with Temporal Consideration

Introduction Experiments were conducted to develop a As the development of Hall effect plasma thrusters comprehensive plume model for Hall effect plasma continues, potential missions beyond basic north-south thrusters. The purpose of the plume model developed in and east-west station keeping are being considered for this this paper is to give system integrators a guide to follow type of thruster. Many of these missions include the when considering antenna-plasma plume interaction. The possibility that the microwave communication link will be plume model was developed around a widely accepted required to pass through the plume of a Hall effect theoretical model of the arc jet plume. The basic arc jet thruster. In addition, new communication systems have plume model was modified to include a temporal and been proposed that include satellite-to-satellite microwave spatial traveling wave caused by the discharge instabilities links that may propagate through the plume of north-south of the thruster. The plume model parameters were station keeping thrusters. As a result, a qualitative and determined using experimental techniques that included quantitative assessment of the impact of Hall effect the use of a swept Langmuir probe, a high-speed thrusters on communication systems is needed. stationary Langmuir probe and a sampling microwave Modem satellite communication systems typically interferometer. The tests were performed on several Hall utilize some form of digital modulation, with the encoded thrusters including a D-55 manufactured by TSNIIMASH information transmitted in the phase or frequency of a (Research Institute of Machine Building), an SPT-100 microwave carrier signal. In addition, a typical satellite manufactured by Fakel Enterprises and a T-100 communication system will have thousands of voice or manufactured by NIITP. data channels from hundreds of sources multiplexed into a single satellite communication channel. The main Nomenclature objective of the multiplexing scheme is to maximize the satellite's channel capacity and thus provide the greatest c speed of light economic advantage to the satellite owner. k local wavenumber A Hall effect thruster produces a plume that is composed primarily of ionized Xenon atoms and an equal kg wavenumber in free space 0 w e er i free s e number of free electrons, thus forming a neutral plasma. ,c carrier frequency The local wavenumber in the plasma, k, can be expressed Op plasma frequency as, So permittivity in free space we -( (x,y,z) (I m, mass of an electron k(x,y,z)= (1) q electron charge where o) is the carrier frequency and c is the speed of n, electron number density light. The local plasma frequency op is given by, A static carrier phase shift caused by plume n(x y,z)q 2 (2) Ao(t) time dependent carrier phase shift pM(x, y, z)= Eom 0 angle relative to the thruster normal where q is the charge of an electron, m, is the mass of an electron, and ne is the local plasma electron number density. The phase difference between waves traveling along a path with a plasma present and one without a plasma present can be expressed as, This work was sponsored by BMDO/IST via a contract x(3) from NASA/LeRC A = [k -k(, y,z)]X' 0