Downstream Flow Analysis of High-Power Helicon Double Gun Thruster with Application to Spacecraft Propulsion Systems

Abstract

Human exploration and fast missions to the outer planets will require a plasma thruster that can operate in the 100 kW to several MW power regime. Such power regimes can only be attained by increasing the size of the thruster, or by using an array of plasma thrusters. Because there are a variety of scale lengths and thermal issues involved in any plasma system, it is unclear which of the two yields the greatest performance. The intent of the Double Gun thruster experiment is to examine whether an array of High-Power Helicon (HPH) thrusters can achieve a higher performance than a single HPH thruster. HPH thruster is an electrode-less space propulsion system that uses a Nagoya type III helical antenna to create plasma, which is then accelerated by the magnetic field generated by series of Helmholtz coils. The Double Gun thruster has two helicon antennae side-by-side. In this paper, the Double Gun thruster's performance is compared to the single gun firing scheme, focusing on the Langmuir probe data at various spatial locations downstream of the two thrusters. The time of flight measurements have shown that there is an interaction between the two antennae, which leads to an increase in exhaust speed from 14 km/s to 17 km/s, albeit at a loss in plasma density.