Indigenous Technology Development of a Prototype Arcjet System

• Main Authors: Hou-YiLee, 李後毅
• Other Authors: Yei-Chin Chao
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/59969358505524053764

碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 98 === The main objective of this study is to study the feasibility of indigenously developing a laboratory-scale arcjet system for space propulsion With its outstanding merits of high specific impulse, the arcjet system can improve the short life-cycle problem caused by rapid consumption of propellant in the traditional chemical propulsion systems. The proposed prototype arcjet system includes arc discharge and power measurement, thrust measurement, propellant supply, cathode cooling, and control and data processing components. Propellant gas was supplied to the arcjet chamber by the propellant supply, and rapidly heated by arc with ohmic heating to further enhance the thrust. The three-channel analysis arcjet model and Rayleigh line flow model were employed to determine the test and design parameters of the arcjet system. From the preliminary test results, the cathode material erosion problem caused by high-temperature heating and oxidation was encountered that significantly lowered the reliability and life span of the arcjet system. Through several tests of different materials, it was found that this problem can be solved by using oxygen-free copper with a thoriated tungsten tip which was oxidation and heat resistant with water cooling. This cathode material can survive throughout the test period. With the ground-test conditions of 1 atm back pressure, H2 mass flow rate, and 1 kW input electric arc power level, the correspondent specific impulse was found to be 110. 105.5, and 94.5 s for the hydrogen mass flow rate of 15.4, 17.9, and 20.3 mg/s respectively, which far exceed the specific impulse 45-50 s served only with cold gas. The calculated thruster efficiency was less than 1 % based on atmospheric experimental results, but it is estimated to exceed 15 % thrust efficiency and more than 400 s specific impulse in the vacuum condition.