Design and Initial Operation of an Optically Accessible ECR Magnetic Nozzle Thruster

Electron cyclotron resonance (ECR) magnetic nozzle thrusters possess several advantages over current state of the art thruster technologies. These include propellant agnosticism and the elimination of the need for a neutralizer cathode. Recent advancements have brought their performance within range of miniaturized Hall and ion thrusters, stimulating interest in further improvements. Such improvements are contingent upon an improved understanding of the electron dynamics inside the source region and the acceleration mechanisms in the nozzle region, which are difficult to study experimentally with electrostatic probes. This work presents the design and initial operation of an ECR magnetic nozzle thruster with an optically transparent source region to facilitate direct optical emission spectroscopy (OES), laser-induced fluorescence (LIF), and Thomson scattering measurements. Langmuir probes are used to estimate electron temperature and density downstream in the plume region while OES is used to determine species makeup and electron density in the source region. Thruster stability is also characterized.