The Air Force Institute of Technology's newest laboratory, the Space Propulsion Analysis and System Simulator (SPASS), has just reached a major milestone.  The inside of the two meter diameter vacuum chamber is currently glowing a distinctive Air Force blue.  This characteristic blue glow is produced when a Hall Effect Thruster ionizes xenon gas.  One of the major advantages of the Hall Effect Thruster or HET is the high “fuel economy.”  It requires less fuel to produce the same level of thrust when compared to a more traditional satellite thruster or spacecraft engine.  The primary purposes of HETs are helping to keep the satellite in place over a particular point on the earth and helping to move the satellite to a new position when necessary.

With the support of the Air Force Research Lab and NASA, AFIT has begun looking into the operation and performance of HETs in several specific areas.  The first experiment in the chamber will focus on measuring the temperature of the thrusters without touching them.  This is known as thermographic imaging.  The operation significantly heats the components of the thruster to temperatures exceeding 600 C.  As the temperature approaches the operating limits of the magnets used in the thruster, their effectiveness can be degraded.  Better understanding the limits of the thrusters gives satellite operators valuable information on the capabilities of their spacecraft.

The SPASS lab is also equipped with measuring devices traditionally used in spacecraft engines.  These devices will be used as both research tools and teaching aids to give AFIT students a practical introduction to spacecraft propulsion issues and engineering.  This gear will be most useful in the development of our next generation of diagnostic tools.  These new diagnostics focus on making measurements without actually disturbing the performance of the engine.  For instance, a technique which uses microwaves can be used to measure the performance of the engines.  This information can be used to calculate the performance (thrust and specific impulse) capabilities of the thruster.  The efficiency of the thruster will be further calculated by a technique using lasers.

In parallel to the research being accomplished on the thruster itself, work on improved parts, or components, is also being pursued.  One integral part, the cathode, is necessary for stable operation.  The cathode neutralizes the exhaust from the thruster to help protect the satellite from damage.  AFIT is currently building two alternative cathodes to test relative performance capabilities separately and will then install them onto a thruster to determine the effect on the entire system performance.