Publication Date

8-2011

Type of Culminating Activity

Thesis - Boise State University Access Only

Degree Title

Master of Science in Mechanical Engineering

Department

Mechanical and Biomechanical Engineering

Major Advisor

Donald G. Plumlee, Ph.D.

Abstract

Miniature electric thrusters have been in development for decades for use in space applications such as satellite station keeping and propulsion. The development of these miniature thrusters has created a need to test and measure a number of parameters, including the amount of thrust (force) generated by the thrusters. As the generated thrust has decreased from the milli-Newton (mN) to the micro-Newton (µN) and nano-Newton (nN) scale, more and more precise thrust measurement stands have been created to accurately analyze their output. Successful measurement of sub micro-Newton thrust levels have been completed by individuals at a number of universities and laboratory institutions, but thrust measurement stands are typically built in larger, more stable, and more expensive vacuum systems than the chamber for the Boise State University (BSU) electric propulsion project.

The need for a thrust measurement stand with µN resolution at BSU arose with the awarding of a research grant to the electric propulsion team. The purpose of this thesis is to support the development of a unique miniaturized propulsion system for use on micro-satellites (<50 kg). The propulsion system will consist of a ceramic-based Micro-Electro-Mechanical System (MEMS) electric propulsion device. The device will be constructed using Low Temperature Co-fired Ceramic (LTCC) materials. The LTCC substrate will be used to embed all electric connections and gas delivery channels within the body of the thrusters. The development of these thrusters at BSU requires the creation of a full spectrum of test and calibration equipment, including a test stand to measure the thrust provided by the thrusters. Knowing the thrust levels provided by the thrusters will allow multi-thruster packages to be constructed with precisely matched equipment and the physical models of the thrusters to be validated.

A µN thrust measurement stand was modeled, designed, fabricated, and calibrated for use with testing and matching thrust levels of future electric thruster designs. A counterbalanced pendulum design, which incorporates the best combination of stability and resolution characteristics, was the final design configuration selected for use in the BSU vacuum chamber system. The counterbalanced pendulum configuration is a unique design based on a literature review of current high-resolution, state-of-the-art thrust measurement stands. The unique design allows thrust measurement in a smaller and less stable vacuum chamber than similar projects typically require. The current thrust measurement stand has a resolution of 0.134 microns/µN in the 0-100 µN range and 0.0125 microns/µN in the 100-300 µN range. Test stand improvements are outlined for the 100-300 µN range.

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