Studies of material surface erosion exposed to plasmas in an electrothermal launcher

Summary form only given. The experimental electrothermal launcher device SIRENS has been operated to measure the erosion of material surfaces subjected to high-heat flux from a high-density, low-temperature plasma (1-3 eV) with a strong applied magnetic field. High-heat flux erosion studies have been performed on Lexan, graphite, copper, brass, stainless steel, and aluminum samples. Initial analysis of the samples indicates a strong axial erosion dependence for metallic surfaces as opposed to uniform ablation for insulators. Surface conditioning through multiple exposure to repetitive discharges showed a decrease in the rate of ablation for a Lexan insulator and an increasing erosion rate for metallic surfaces. Externally applied parallel magnetic fields of up to 10 T were applied in experiments with Lexan samples to demonstrate the magnetic vapor shielding phenomenon. The result indicates a threshold for the onset of the magnetic vapor shielding effect. For the field above the threshold, a reduction of the surface ablation of the sample was observed, implying a reduction of the energy transport through the vapor shield with applied field