Performance Modeling of a Thrust Vectoring Device for Hall Effect Thrusters

Abstract

The ability to control the thrust vector direction on electric propulsion devices opens new possibilities for mission optimization. The addition of an external magnetic steering system and the nonsymmetric localized injection of propellant have been proposed to deviate the ion beam of a PPS®1350 Hall effect thruster. A two-dimensional hybrid model has been used to evaluate the preliminary design. Simulated results suggest the ion beam angular distributions may be varied in the range of 10 deg by changing the current in the external steering coils. However, a magnetic topography with field lines directly connected from the outer steering pole to the anode leads to a reduction of the Hall effect thruster performance. The erosion of the walls increases drastically as a function of the magnetic lens orientation (6 mm for 1000 h of thruster operation for high coil currents in the external coils). A localized axial injection of atoms has a positive effect on the steering angle of the ion beam (a few degrees), but exhibits additional erosion of approximately 10-15%. Qualitative comparisons with experimental results confirm the simulated trends. Nomenclature B o;x , B o;r = axial, radial components of the magnetic field in the centerline in the exhaust plane D = position of the injector E = ion energy E ?= electric field component perpendicular to the magnetic field E th = sputtering energy threshold e = electron charge constant g = constant gravity on Earth I d , I i = discharge, ion current I ion = ion beam divergence I sp = specific impulse J in , J out , J back = internal, external, back coil current density L = channel length _ m = xenon anode mass flow m i = ion mass m w = mean mass of the wall material n = plasma density P = fraction of neutrals released into the channel through the ceramic wallmean velocity Y = sputtering yield = angle between the axial axis and the ion velocity _ m = mean angle of the ion beam divergence = magnetic field line orientation i , i;? , e;? = ion flux, ion, electron cross-magnetic field flux "= electron mean energy , u , c , E = thruster anode, propellant, current, beam energy efficiency ?= cross-magnetic field electron mobility w = mass density of the wall material = azimuthal direction = number of times the current crosses the magnetic field lines r ?= cross-magnetic field gradient

Contactless steering of a plasma jet with a 3D magnetic nozzle

“…Moreover, these pointing mechanisms introduce a number of additional issues, such as the need for flexible piping and connectors to the thruster, higher complexity for thermal control, and the damping of shocks and vibrations. TVC concepts using mechanically displaced ion grid optics [6], asymmetric gas injection and magnetic fields in Hall effect thrusters [7], or acting on the plasma jet by means of a fixed, large external coil located on one flank of the thruster [8] have been proposed as alternatives.…”

A Comprehensive Cold Gas Performance Study of the Pocket Rocket Radiofrequency Electrothermal Microthruster

“…The thrust from cold gas or electrothermal thrusters is derived from the momentum of the exhausted neutral gas propellant, as distinct from electrostatic or electromagnetic thrusters, where the thrust is defined as the force in reaction to the acceleration of ions through an electric field [71,72]. PR belongs to the former class of neutral gas thrusters; it operates as an electrothermal microthruster when RF power is supplied to ionize and heat the neutral gas propellant [30,31], and as a cold gas microthruster when no RF power is supplied.…”

Mode transition of the cylindrical Hall thruster with the near-anode cusp magnetic field

“…It is well-known that the plume is mainly composed of the ion beam originated from the ionization region and accelerated by the electric field, its IEDF f IEDF depends strongly on the comprehensive effects of the ionization process and acceleration process [2,13]. Because the ions undergo electric potential declining monotonically in their process of acceleration, the monotonicity of the angular distribution of the f IEDF depends on the monotonicity of plasma density distribution in the ionization region [8,18,[28][29][30]. Assuming that only one ionization region is located in the thruster, the ions generated in this ionization region are accelerated by the same electric field and the most probable ion energy in the f IEDF constituted by these ions should be decreased monotonically with the increasing of the angle.…”