Research of cathode plasma during a S-band relativistic magnetron operation

Summary form only given. We report results on spectroscopic research of the explosive emission plasma which is formed at the cathode surface during the operation of a S-band relativistic magnetron with microwave power of ~100 MW powered by Liner Induction Accelerator (4 kA, 300 kV, 120 ns). Plasma parameters (density, temperature, expansion velocity and uniformity) were studied with time- and space-resolved framing images of the plasma by fast framing camera, fast photo-diode with narrow band interference filters and visible spectroscopy. The plasma ion temperature was determined using the Doppler broadening of different spectral lines (H_alpha, H_beta, CII , CIII, and CIV) and the plasma electron density were determined using the Stark broadening of H_alpha and H_beta and the comparison of the H_alpha/H_beta and different CII, CIII, and CIV population ratios with results of collisional radiative modeling.