Spectroscopic Analysis of the Self Magnetic Pinch Diode Used in Flash X-Ray Radiography Research

Summary form only given. Investigations are underway at Sandia National Laboratories' RITS-6 accelerator facility (10 MV and 120 kA) to study plasma formation and propagation in electron beam diodes used for flash X-ray radiography. In particular the Self Magnetic Pinch (SMP) Diode has been studied using time and spatially resolved optical diagnostics to gain an understanding of the role of plasmas in diode performance. The SMP diode employs a hollow metal cathode and a thin aluminum foil anode in front of a high atomic number target to produce bremsstrahlung X-ray radiation. Results show plasma formation beginning during the second half of the (~70 ns) X-ray radiation pulse. While plasma formation is observed on both the cathode and anode, it is predominantly the anode plasma which expands across the A-K gap region (~10 mm). Data shows the presence of hydrocarbon and aluminum ion species with expansion velocities of a few 10's of cm/microsecond. Spectroscopic analysis is performed using time-dependent, collisional-radiative models to provide plasma density and temperature information. Diagnostics include optical imaging using gated, intensified CCD cameras, and gated/streaked spectra obtained using 1 meter Czerny-Turner monochromators. Recent results are presented.