Optical Spectroscopy and Magnetic Field Profile Measurements on the Self Magnetic Pinch Diode.

[摘要] The Self-Magnetic Pinch (SMP) diode has been tested at Sandia National Laboratories on the RITS-6 accelerator for use as a flash x-ray radiography source. The diode consists of a hollow cathode that emits electrons through an approximately 1-cm vacuum A-K gap onto a high-Z material. The electron beam pinches from its own magnetic field as it traverses the gap. Plasmas form on the electrode surfaces and expand into the gap, decreasing the diode impedance over time. Visible spectra of the electrode plasma have been taken during the radiation pulse using a high resolution spectrometer and a lens coupled fiber array focused across the anode surface of the diode. Electron temperatures have been determined from C III/ C IV line ratios. Electron densities have been estimated from Stark broadened line emission and densities have been estimated from several different ionization states. These measurements suggest that a large axial density gradient is present on the diode surface, with densities varying by up to an order of magnitude within ~1 mm of the anode target surface.Zeeman splitting measurements of C IV suggest magnetic fields of 3-5 T a few mm from the diode axis. These results differ from LSP simulations of the beam current, and suggest that a significant fraction of the total current density may be outside the few mm x-ray source diameter. Several dopants have also been characterized for Zeeman splitting, intensity, and their effect on the SMP diode performance. Zeeman splitting was measured on the Al III 4s-4p transition and this line may be used in the future to further spatially isolate these measurements. Additionally, it was found that salt coatings on the diode lengthened the radiation pulse. Finally, measurements of the C IV Zeeman line splitting on the anode surface represent the first experimental estimates of current distribution within a diode.

[发布机构] University of Michigan

[效力级别] Zeeman Splitting

[关键词] Spectroscopy;Zeeman Splitting;Self Magnetic Pinch Diode;Physics;Science;Nuclear Engineering and Radiological Sciences