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Graduate Exam Abstract


Jonathan Grava

M.S. Final

December 8, 2006, 1:00 PM

Wagar 107B

Soft x-ray interferometry of dense colliding plasmas in semi-cylindrical cavities


Abstract: This thesis discusses the study of dense aluminum and copper plasmas created by laser irradiation of semi-cylindrical targets using soft x-ray laser interferometry. The interferograms were analyzed to obtain electron density maps that describe the plasma evolution. The aluminum and copper plasmas show similar general behavior but different expansion velocities. A high energy short duration (120 ps) optical laser pulse was used to irradiate half-cylindrical cavities with intensities of 1.0×1012 to 1.5×1012 Wcm-2, creating plasmas that expand away from the target surface and converge on axis near the center of the cavity. Plasmas generated irradiating copper and aluminum targets were studied. The converging plasmas were measured to create a localized region where the electron density is measured to reach 1×1020 cm-3 and higher. The diagnostics technique used to probe these plasmas combined a compact 46.9 nm laser source with a robust soft x-ray interferometer based on diffraction gratings. The short wavelength of the soft x-ray laser source enables plasmas with high densities and large length scales to be probed. The nanosecond duration of the probe pulses enabled to take snapshots of the plasmas at various stages of its evolution. These results further extend the use of soft x-ray laser interferometry as a powerful diagnostic tool for dense plasmas.

Adviser: Dr. Jorge Rocca
Co-Adviser: Dr. Mario Marconi
Non-ECE Member: Dr. Chiao-Yao She (Physics)
Member 3: NA
Addional Members: NA

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