Feasibility of low energy plasma torch for reaction control thruster ignition.

摘要

A DC--thermal plasma jet is proposed as a reliable ignition source for reaction control system (RCS) thrusters employing oxygen with hydrocarbons, like methane. Industrial plasma torch systems are analyzed to understand the behavioral characteristics of DC--thermal plasmas. Nitrogen is used as a working gas for the source of plasma jet to understand the general mechanism of thermal plasma formation. DC--thermal plasmas require high electrical energy to maintain their arc discharge status which presents challenges in space systems. The purpose of this study is, therefore, to find a suitable configuration which minimizes power consumption.;Various physical and electrical conditions relate to a thermal plasma formation. In this study, the input voltage (221--332V) and pressure (5--15 psi) are applied as initial conditions. The DC--power module and starter module are designed as plasma drivers and a commercial off--the--shelf torch head is used for this research. The normalized method is developed to estimate the arc temperature. Test results show that the lowest power consumption and arc--starting voltage are 1,321W and 248.8 VDC, respectively. In addition, it is found that the current is a major factor for varying the mass flow rate.;Since the lowest power consumption is still high, future improvements and research should focus on integrating a high--power and lightweight energy source, developing a high--frequency and half--duty cycle power system, and incorporating a composite cathode. In addition, a new conceptual torch design is proposed to be considered as an igniter for RCS thrusters. The next step would be to repeat the plasma torch tests with the new configuration at ambient and vacuum conditions. These would be followed by combustion tests to verify the actual functionality of the plasma igniter for RCS thrusters with various oxidizer and fuel mixture ratios. In parallel, research should focus on miniaturization of the electrical system.