Method for the erosion rate measurements of stationary plasma thruster insulators

Alona Khaustova,Andrej Loyan

doi:10.15587/1729-4061.2017.99295

Abstract

Despite the fact that for many years the stationary plasma thruster (SPT) has been used in space, this technology has not yet been fully studied. One of the research directions to improve SPT characteristics is the increase of thruster lifetime. This can be achieved with the research of the discharge chamber (DCh) walls erosion rate as a function of different thruster operational modes. The analysis of the SPT DCh wear rate diagnostics methods was carried out. It is shown that the considered methods cannot provide measurements of the insulators erosion rate separately during the experiment. The method of optical emission spectroscopy with plasma scanning through collimator (OESSC) was developed. The method allows registration of radiation separately for each of SPT DCh walls directly during the experiment. According to this, the experimental time of different SPT operational regimes research was reduced by 98 %. Experimental equipment of the OESSC method was developed, produced and tested. It consists of the high-resolution spectral block with the range of 240...820 nm and the optical detector positioning system. A set of experiments were provided with the OESSC method. As a result, the inner and outer insulators erosion rates are researched as functions of thruster operational regimes. It is shown that for the outer and inner coils currents of 5 and 6 A, respectively, there is a uniform wear of DCh walls. For such SPT operational regime, the difference in the insulators specific relative erosion rates is 2 %. The results of the OESSC method measurements allowed increasing the anode block lifetime significantly

Highlights

Stationary plasma thruster (SPT) is one of the plasma thruster (PT) types systematically applied in space since the past century [1]
The experiment with the OESSC method was performed with the following thruster parameters: discharge voltage (Ud) 300 V, anode mass flow rate 4 mg/s, cathode mass flow rate 0.35 mg/s
The results show that the thruster lifetime in such an operational regime will be 2.2 times higher

Summary

Introduction

Stationary plasma thruster (SPT) is one of the plasma thruster (PT) types systematically applied in space since the past century [1]. Despite the fact that some SPT characteristics (efficiency, specific impulse, lifetime), are dominated by the ion plasma thruster (IPT) parameters, there is a great interest to in this type of PT. It is seen from a number of SPT significant advantages [2]. If to compare SPT with IPT, it has relatively simple design and technology of production. Propulsion system on the base of SPT has better characteristics such as weight and production time. Relevance for the SPT development is the number of customers of this plasma thruster. One of the main areas of SPT modernization is the thruster lifetime [3]

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Conclusion