Plume Characteristics of an Electrothermal Plasma Microthruster

High-resolution digital images of the expansion plume from an electrothermal capacitively coupled radio frequency (13.56 MHz) plasma microthruster were captured for argon and nitrogen discharges in lowand high-pressure operating regimes. The sheath near the thruster exit is clearly visible in all images, and the observed expansion plume features are consistent with previous experiments on electron density profiles within the discharge.