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Thesis (M.S.)--University of Michigan, 1976.

Thesis (M.S.)--University of Michigan, 1985.

Shock waves generated by laser-driven ablation in solids have provided a great opportunity for the study of dense plasmas. The work presented in this thesis include measurements of Hugoniot curves and the reflectivity of shocked aluminum. In these experiments, planar aluminum targets were irradiated with a 0.53µm, 2ns (FWHM) laser pulse at irradiances up to ~ 10¹⁴/cm². Temporally and spectrally resolved measurements of the target rear surface luminous emission have yielded the shock speed and temperature Hugoniot curve which showed good agreement with equation of state predictions. In addition, temporally resolved reflectivity measurements of the shocked target rear surface compared well with a theoretical model for the electrical conductivity of a dense plasma. For copper and molybdenum targets, both the luminescence and the reflectivity measurements indicated that the heating of the dense target material was dominated by radiation transport from the coronal plasma rather than shock heating. An analysis of the molybdenum results indicate that x-ray shine-through may be the dominant energy transport mechanism to the target rear surface, whereas for the copper targets the transport process appears to be much more complex. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

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This thesis deals with several theoretical aspects of the interaction of an intense femtosecond laser pulse with a plasma. A mechanism for the enhancement of the collisional absorption of light at high intensities is described, involving the direct excitation of collective modes of the plasma, and the importance of this mechanism for a solid-density laser-produced plasma is studied under a range of conditions. An intensity-dependent collision rate is used in a numerical calculation of the reflectivity of a steep-gradient plasma, such as might be produced by an intense femtosecond laser pulse, and the conditions required to maximize absorption at high intensities are determined. The relative contributions of field-induced ionization and collisional ionization in laser-produced plasmas are studied, and it is shown that the behaviour of a gaseous plasma is almost solely governed by the field-induced process. A model is developed to simulate the propagation of an intense femtosecond laser pulse through an initially neutral gas, and this model is used to make predictions about spectral modifications to the laser pulse. Under certain conditions the spectrum is significantly broadened and suffers an overall blue shift. Quantitative fitting of theoretical spectra to experimental results in the literature is attempted, but is complicated by associated defocusing effects in the plasma. Field-induced ionization can produce a gaseous plasma which is significantly colder, for the same degree of ionization, than a plasma produced by collisional ionization. One possible application for a cold highly-ionized plasma is in a recombination x-ray laser, and the propagation model allows the calculation of the plasma temperature, which is a crucial parameter in assessing the feasibility of such schemes.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: Charles Chiu and Boris Breizman. Vita. Includes bibliographical references. Also available from UMI.

Thesis (M.S. in Applied Physics)--Naval Postgraduate School, June 2002. / Thesis advisor(s): William L. Kruer, William B. Colson. Includes bibliographical references (p. 43). Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 96-99). Available also in a digital version from Dissertation Abstracts.