Design, fabrication and characterization of mems based micro heater for vaporizing liquid microthruster
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Abstract
Demand and development in the space industry are conditioning more costeffective satellites without a reduction in functionality. One of the means of satisfying thus requirements is miniaturization. Constructing, smarter, lighter and cheaper satellites to reduce the cost of delivering it to the orbit as the main chunk of mission cost falls on delivering the satellite to space. Lighter versions of satellites called nano-satellites (CubeSats) which could be fabricated in mass scale in a reproducible manner might be a suitable solution. In simple words nanosatellite is a state of the art device packed with advanced logic electronics, sensor and actuator arrays as well as power management systems, etc. to perform numerous tasks. Considering the already high cost for large scale integration of various components it is very important to extend the lifetime of the devices as much as possible. Beside radiation which is one of the main reason for the failure of the components, satellites are useful only if they remain in the orbit and not deviate from the specific path it was set due to drag. Therefore the propulsion system is required to control the altitude to increase the operational lifetime of the satellite. The project is a continuation of the work in realizing a new generation of noble green Vaporizing Liquid Micro Thruster (VLM) functioning in environmentally friendly propellant(water) fabricated in Else Kooi Laboratory (EKL) with the cooperation of Aerospace Engineering (AE) faculty with an intention of contributing to the DELFFI mission. Thesis includes fabrication and testing of a thruster with a heavy emphasis on improving the performance of the heating chamber. Fabrication was accomplished by designing modules separately and assembling them through part by part exposure in the lithography. Such an approach was taken due to the need for systematic analysis of numerous factors affecting performance by altering them and observe the effect on performance. Several heating chambers were designed with varying performance attributes and tested on its ability to deliver heat efficiently as well as affect to thruster performance like pressure drop. In addition to it, several fabrication techniques not used previously for the fabrication of thrusters were experimented and implemented on making various channel structures giving freedom of more 3D design. As a result novel type of Microelectromechanical Systems (MEMS) VLM heating chambers were fabricated by modular design and tested. Developed process is robust and flexible which allows to manufacture different types of VLM thrusters depending on operation demand and suited for integration. The novelty introduced in the project is step-wise heating as well as the application of a new type of localized heating chamber with improved geometry for enhanced heating efficiency and for wall temperature measurements.