Direct Current Plasma Electron Source for Electric Propulsion Applications Using Atomic and Molecular Propellants

Abstract

Abstract-The design and performance of a novel direct current neutralizer for electric propulsion applications are presented. The neutralizer exploits an E×B discharge to enhance ionization via electron-neutral collisions. Tests are performed with helium, argon, xenon, air and water vapour as working gases. The I-V characteristics and extraction parameters are measured for both atomic and molecular gases. The maximum partial power efficiency is 4.2 mA/W in argon, 2.7 mA/W in air and 2 mA/W in water vapour. The typical utilization factor is below 1 and the power consumption is less than 120 W. A semi-empirical model is derived to predict the performance of direct current plasma cathodes using atomic gas. A comparison with existing plasma cathodes and conventional LaB6 cathodes is presented and design optimisations aimed at improving the performance are proposed.

Ion plume investigation of a Hall effect thruster operating with Xe/N2 and Xe/air mixtures

“…The list of runs and the related operating parameters of the thruster (mass flow rate, anode voltage and power) are shown in table 1. The run numbering follows that of the full database found in the appendix of the thesis of Gurciullo [37]. It is worth noting that a certain amount of xenon was needed in order to maintain a stable discharge.…”

“…This thruster is optimised to operate with xenon and it is expected that the use of molecular propellant lowers the propulsive performance. Nevertheless, the main objective of this study is to investigate the ion plume composition of a HET operating with molecular propellants, rather than to estimate (or optimise) the thruster's performance metrics, as detailed in the thesis of Gurciullo [37].…”

“…The extended derivations of the formulae above can be found in the thesis of Gurciullo [37]. Here, k and j are variables used to define the kth and the j th ion species present in the Wien filter spectrum, respectively, n k is the ion density, I k is the ion current at the entrance of the filter, Z k is the ion charge number, m k is the ion mass, I p,k is the contribution of the kth ion species to the ion current collected by the Wien filter collector, and V plates is the potential difference between the plates within the filter.…”

A mesh refinement method for low‐thrust orbit transfer problems

“…An orbit transfer scheme is usually accomplished by mainly two approaches: continuous thrust or a series of instantaneous and discrete velocity impulses 1 . In recent years, with the fast development and the economic savings due to the reduction in propellant consumption and structure size, electric propulsion technologies have obtained increasing engineering and scientific attention 2–4 . An electric engine can generally provide a specific impulse 10 times larger than that of a chemical engine, but the associated thrust acceleration is negligibly small compared to that of the Earth gravity.…”

“…1 In recent years, with the fast development and the economic savings due to the reduction in propellant consumption and structure size, electric propulsion technologies have obtained increasing engineering and scientific attention. [2][3][4] An electric engine can generally provide a specific impulse 10 times larger than that of a chemical engine, but the associated thrust acceleration is negligibly small compared to that of the Earth gravity. Meanwhile, a transfer process using an electric engine can take several months and hundreds or thousands of revolutions; consequently, the number of burn-coast arcs will be so large that both the initial guess and the convergence will be dramatically difficult to obtain.…”