Antenna Design Method and Performance Improvement of a Micro Ion Engine Using Microwave Discharge

Abstract

In this study, we are proposing a novel miniaturized ion engine system μ1. Recently microspacecraft and propulsion system to be installed there have attracted a lot of attentions. To accomplish the miniaturization of spacecraft component, multifunctionalization of devices are key technologies. The ion engine we are proposing here is distributed on microspacecraft and give a number of functions and strong redundancy to the spacecraft. To realize this concept, we introduced a novel idea for an ion engine system. That is to use single plasma source as both ion beam source and neutralizing electron source only by electrical connection. This ion engine system is released from the necessity of a number of neutralizers. Our concept requires a plasma source driven by very low power microwave. Here we proposed an antenna design method for a small plasma source using microwave discharge, and developed a miniaturized ion engine. As a result, the performance of the miniaturized ion engine was improved up to the ion production cost of 240 V and propellant utilization efficiency of 40 % at the input microwave power of 1.0 W and mass flow rate of 0.15 sccm.

Three-dimensional particle-in-cell simulation of a miniature plasma source for a microwave discharge ion thruster

“…For the plasma parameter range calculated in the present study, the grid spacing ( x, y, and z) is small enough to satisfy the condition: the Debye length λ D is roughly larger than x/3, y/3, and z/3 [20]. As shown in figure 8(b) (also see figure 9 in [21]), the plasma discharge can hardly be observed in the region between the antenna and the ring magnets especially at low powers (<1 W). The discharge characteristics is not considered to be influenced significantly by the space between inner and outer ring magnets; and thus the space is neglected and filled with metal for simplicity.…”

Effects of secondary γ-electrons from accelerator grid under ion impingement in gridded ion sources

“…source. In the high-P w regime of a 2 cm ECR ion source, I b also jumped (refer to figure 8 in reference [42]), but the author did not even mention this abnormal phenomenon. In the magnetic configuration of this gridded ion source, the magnetic field lines are mainly parallel with the antenna's surface, so that the extraordinary wave (X-wave) excited by the antenna does not induce the skin effect and the subsequent I b jump due to low n e .…”

Water and xenon ECR ion thruster—comparison in global model and experiment

“…The length was defined as the distance from the surface of the magnet to the upstream of the screen grid. The design was based on the xenon ion thruster used in two spacecraft operated in space, and the details of the design can be seen in references [36][37][38].…”

“…From the viewpoint of preventing oxidation, an electron cyclotron resonance (ECR) ion thruster is one solution in which a water propellant ion thruster is realized. It generates plasma without an electrode in the discharge chamber and also utilizes ECR plasma as a neutralizer with a negatively biased voltage [35][36][37][38][39]. The concept of an ECR water ion thruster was verified by Nakagawa [22] and its thrust was directly measured using a pendulum-type thrust stand [40].…”