Type of Culminating Activity
Master of Science in Mechanical Engineering
Mechanical and Biomechanical Engineering
Donald G. Plumlee, Ph.D.
Electric thrusters have been used for many years for orbital station-keeping and propulsion. As technology advances, smaller satellites are possible that require less thrust. The resulting miniature electric thrusters need low-weight and compact designs. This thesis specifies the design, fabrication, and testing of a thruster and its fluid delivery system designed for use with a micro-satellite weighing less than fifty kilograms.
The advent of Micro-Electro-Mechanical Systems (MEMS) has sparked a new market with incredibly small scale designs. Using this technology with Low-Temperature Co-fired Ceramic (LTCC) materials has spawned the new distinction of Ceramic Micro-Electro-Mechanical Systems (C-MEMS). The thruster body is made entirely out of LTCC and it has embedded electrical connections and gas delivery channels integrated wholly within the thruster. These thrusters are tested inside a vacuum chamber system set up at Boise State University to simulate the pressure ranges seen in typical space applications. Plasma generation requires adequate gas pressures localized to the time-varying electric field inside of a vacuum. Prior testing for prototype thrusters at Boise State University proved that a single hole central gas injection point was not taking full advantage of the locations of high electric field intensity. This was the driving force to generate a computational fluid dynamics (CFD) model to simulate the pressure ranges as they applied to the areas of high electric field intensity. ANSYS Fluent was used as the modeling software to simulate the pressure ranges of the gas seen inside the thruster body. Experimental testing was done to verify the validity of the Fluent modeling. Electric field intensity was used as a driving force for the design of the gas outlets and their locations.
The resulting thruster design demonstrated the successful ability to use LTCC as a substrate for a miniature thruster with fully embedded electrical components and gas channels. Experimental testing showed that a multiple hole gas injection concept created a higher localized pressure within the thruster cylinder, which increases plasma efficiency. The increase in localized pressure was as high as 49.8% larger than a single injection hole design. The experimental tests were also used as a method of validation for a CFD model that could be used in future iterations of the thruster to improve the locations of the thruster gas injection holes. Further work should be done with the external connections to the LTCC body to improve long-term durability.
These results imply that LTCC is a viable medium for creating miniature thrusters for micro-satellites. The LTCC creates a hermetically sealed fluidic pathway for neutral gas to travel through, which reduces the size of the overall thruster considerably. A thruster made out of LTCC is both small in size and has excellent qualities to survive the harsh environment of space.
Reis, Derek J., "The Design, Fabrication, and Pressure Testing of a Low-Temperature Co-Fired Ceramic Electric Propulsion Thruster" (2013). Boise State University Theses and Dissertations. 357.