SBIR-STTR Award

The objective of this proposal is to demonstrate greatly extended lifetimes for existing Hall Effect Thruster (HET) designs by using solid diamond components. Polycrystaline diamond is now readily available as an engineering ceramic in sizes suitable for use in HET’s because of the rapid progress made in plasma-assisted Chemical Vapor Disposition. Diamond has many superior chemical and physical properties, most notably thermal conductivity and resistance to sputtering, that make it an ideal choice for the insulating material of an HET.

Benefits:
A notorious problem with Hall Effect Thrusters is that they don''t scale down in size efficently. Even thier lifetime reduces out of proportion with size. This improvement would open a whole new catagory of spacecraft to the use of medium and low power HETs. It has the potentenial to increase the life of high power HETs to the point where they are superior to Ion thruster now used for deep space missions. Abstract: Solid Diamond insultors Incresed lifetime on an exsisting design True life test til failure Reduced erosion and secondary emission

Concern exists in the space industry about the effect of µPPT and the Hall Effect Thrusters on spacecraft and their power generation systems. Numerical modeling data must be verified with on-orbit data because ground measurements of contamination effects in vacuum chambers do not fully reflect space conditions. Thus, a sensor package will be manifested aboard an upcoming spacecraft flight for the purpose of developing a predictive capability for how electric propulsion thrusters interact with typical spacecraft. This sensor package will consist of the Propulsion Instrumentation Electronics Package (PIE), which will be used to set, control and sample 30 different sensors. The PIE is smaller, lighter, and more robust than typical central processing units; it uses field programmable gate arrays to store and pass commands, set biases, and collect data from the sensors before forwarding it to the spacecraft bus. Plume environment characterization sensors will include one ion spectrometer that will measure mass and energy distributions of ions (primarily Xe+ and Xe++) emitted from the thruster, and two electron probes that will measure electron density and temperature of the plasma environment. Surface contamination characterization sensors will include two solar cell sensors, which will measure specific environmental effects on the solar arrays by characterizing changes to the current vs. voltage response curve of the solar cell over time, ten photometer sensors, which will measure the contamination and erosive effects of electric propulsion thrusters on the optical properties of materials, and ten radiometer sensors that will measure contamination and the erosive affects to the thermal absorption and emissive properties of spacecraft surface materials. Testing and verification of PIE functionality was accomplished with hardware and software that simulated spacecraft sensors in laboratory conditions.

Benefits:
The primary benefits is increased on orbit life of Hall Effect Thrusters. At present thrusters in the 200 to 500 watt range fail after 900 to 1200 hours of use. This improvement should more than double the life of these thrusters. The ability to bond diamonds will cross into many other fields. Providing additional commerial applications. Abstract: Laminated diamonds, Hall Effect Thruster, High temperature insulators, Insulator erosion, Extended life, Chemical bonding of Diamonds