Experimental investigation on the evolution of plasma properties in the discharge channel of a pulsed plasma thruster

Pulsed plasma thrusters (PPTs) are an attractive form of micro-thrusters due to advantages suchas their compactness and lightweight design compared to other electric propulsion systems.Experimental investigations on their plasma properties are beneficial in clarifying the complexprocess of plasma evolution during the micro-second pulse discharge of a PPT. In this work, themulti-dimensional evolutions of the light intensity of the PPT plasma with wavelength, time, andposition were identified. The plasma pressure was obtained using an iterative process withcomposition calculations. The results show that significant ion recombination occurred in thedischarge channel since the line intensities of CII, CIII, CIV, and FII decreased and those of CIand FI increased as the plasma moved downstream. At the center of the discharge channel, theelectron temperature and electron density were in the order of 10000 K and 10 ¹⁷ cm ⁻³,respectively. These had maximum values of 13 750 K and 2.3×10 ¹⁷ cm ⁻³ and the maximumtemperature occurred during the first half-cycle while the maximum number density wasmeasured during the second half-cycle. The estimated plasma pressure was in the order of 10 ⁵ Paand exhibited a maximum value of 2.69×10 ⁵ Pa.