Characterization of an Optically Accessible ECR Magnetic Nozzle Thruster*

Electron cyclotron resonance (ECR) magnetic nozzle thrusters are an attractive prospect for low-power small satellite propulsion applications. Their advantages include propellant agnosticism and no need for a neutralizer cathode. While their performance has historically been poor, recent developments have brought them to parity with miniature Hall effect and ion thrusters of similar input power. Further improvements are theoretically possible, but are contingent upon improved understanding of the electron dynamics in the source region and the acceleration mechanisms in the plume region. To this end, we have developed a thruster with an optically transparent source region, providing superior access for non-intrusive diagnostics such as optical emission spectroscopy (OES), laser-induced fluorescence (LIF), and Thomson scattering. This work presents the characterization of this thruster, operating on argon between 0.5-5 sccm and 30-70 W using electrostatic (Langmuir, Mach) probes in the plume region coupled with OES in both the source and plume region.