Particle-in-cell simulation of Hall thruster plasmas reveals a plasma-sheath instability manifesting itself as a rearrangement of the plasma sheath near the thruster channel walls accompanied by a sudden change of many discharge parameters. The instability develops when the sheath current as a function of the sheath voltage is in the negative conductivity regime. The major part of the sheath cu...

Multiscale Modeling of Hall Thrusters Hall thrusters are efficient space propulsion devices that produce thrust by accelerating quasineutral plasma. The thruster consists of a channel with one end open to the ambient environment. The neutral propellant is injected at the closed end and is ionized by electrons produced by an externally mounted cathode. A radial magnetic field is applied across t...

* Presented as Paper IEPC-03-0069 at the 28 International Electric Propulsion Conference, Toulouse, France, March 17 – 21, 2003. Published by the Electric Rocket Propulsion Society with permission. † Graduate Student, Aerospace Engineering, [email protected]. ‡ Graduate Student, Aerospace Engineering. § Associate Professor and Laboratory Director. A method for delivering a symmetric double ...

A new electric propulsion device concept takes advantage of residual helium gas that is trapped in the chemical propellant feed system and currently unused at end of life. The helium ion thruster provides additional propellant resources to extend satellite lifetimes and transfer geostationary orbit space assets to ultrasafe disposal orbits. The predicted capability, if fully allotted to the dis...

This paper presents a recent characterization of the thrust efficiency and specific impulse of a low power, linear-geometry (non-coaxial) Hall thruster with an open electron-drift current. The thruster was constructed with a boron-nitride insulating channel surrounded by a magnetic circuit served by four electromagnet coils, and was designed to operate in the 100-Watt power class. A survey of t...

This paper considers thruster dead zones and saturation limits in fine motion control of underwater robots. Thruster dead zones and saturation limits are major nonlinear elements that make fine motion control of underwater robots difiicult. If the vehicle is designed with a redundant thruster configuration, the dead zone and the nonlinear region around it can be completely avoided by implementi...

The ffx code was used to investigate the lifetime and propellant throughput capability of the High Power Electric Propulsion (HiPEP) thruster ion optics as part of NASA’s Project Prometheus. Erosion predictions are presented as a function of beamlet current, accel grid voltage, and propellant utilization efficiency. These predictions were then compared to the lifetime goals of the thruster, and...

A compact high-speed reciprocating probe system has been developed in order to perform measurements of the plasma parameters by means of electrostatic probes in the discharge and the plume of a Hall thruster. The system is based on a piezoelectric linear drive that can achieve a speed of up to 350 mm/s over a travel range of 90 mm. Due to the high velocity of the linear drive the probe can be r...

Hall thrusters are an attractive form of electric propulsion that are being cleveloped to replace chemical systems for many on orbit propulsion tasks on communications satellites. A major concern in the use of these devices is the possible damage their plumes may cause to the host spacecraft. In this paper, the present status of computer modeling of Hall thruster plumes is reviewed in the conte...

| This paper addresses the potential for energy reduction obtained by using dynamic line tension-ing in thruster assisted position mooring systems. Traditionally , mooring systems have been designed in such a way that thruster assistance has not been neccessary under normal environmental conditions. However, as oil production moves into deeper waters, such over-dimensioned mooring systems are n...