Plume Divergence and Discharge Oscillations of an Accessible Low-Power Hall Effect Thruster

Abstract

Hall effect thrusters (HETs) are an increasingly utilized proportion of electric propulsion devices due to their high thrust-to-power ratio. To enable an accessible research thruster, our team used inexpensive materials and simplified structures to fabricate the 44-mm-diameter Western Hall Thruster (WHT44). Anode flow, discharge voltage, magnet current, and cathode flow fraction (CFF) were independently swept while keeping all other parameters constant. Simultaneously, a Faraday probe was used to test plume properties at a variety of polar coordinate distances, and an oscilloscope was used to capture discharge oscillation behavior. Plasma plume divergence angle at a fixed probe distance of 4.5 thruster diameters increased with increasing anode flow, varying from 36.7∘ to 37.4∘. Moreover, divergence angle decreased with increasing discharge voltage, magnet current, and CFF, by 0.3∘, 0.2∘, and 8∘, respectively, over the span of the swept parameters. Generally, the thruster exhibited a strong oscillation near 90 kHz, which is higher than a similarly sized HET (20–60 kHz). The WHT44 noise frequency spectra became more broadband and the amplitude increased at a CFF of less than 1.5% and greater than 26%. Only the low flow and low voltage operating conditions showed a quiescent sinusoidal discharge current; otherwise, the discharge current probability distribution was Gaussian. This work demonstrates that the WHT44 thruster, designed for simplicity of fabrication, is a viable tool for research and academic purposes.

Designing of Light Weight Hall Thrusters with Key Discharge Parameters

“…Electrons need to travel at a specific speed in order to remain trapped in the channel since the magnetic field is what holds them there. [3] The electric field of the device is used to accelerate ionized propellant away from the thruster and to transfer electrons from the cathode into the channel. Electrons generated by the cathode are attracted into the channel because of the cathode's negative potential in relation to the anode.…”

“…Electrons generated by the cathode are attracted into the channel because of the cathode's negative potential in relation to the anode. [3] Electrons need to travel at a specific speed in order to remain trapped in the channel since the magnetic field is what holds them there. They stay in the channel's plasma for a while, but ultimately, they run out of energy due to collisions with the wall or other particles (such neutrals).…”

“…The azimuthal direction is shown by the Fleming left hand rule, the cross arrangement of the electric and magnetic fields causes electrons to form the Hall Current. [3] VI.…”

“…The magnetic lens of heavy-weight rockets might be less concerned with precise ion control and more with overall plasma stability and performance. [5]…”

Experimental and numerical studies of low power Hall thruster performance

“…The ion velocity distribution is also affected by the background pressure in low-power Hall thruster [11]. Matthew Baird et al obtained a quiescent sinusoidal discharge current in only the low flow and voltage operation condition [12]. Duan X Y et al investigated the far-field plasma characterization in a 600W Hall thruster [13].…”