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This is a preprint of a paper intended forpubli_tion in • jourual orproceedin8_. Since : " _:__: changesmay be madebefore publication,thispreprint is madeavailablewith the ", i_i: ii understanding that it will not be cited or reproduced without the permission of the :.

An ultraviolet-laser-ionized channel in low-pressure benzene has been successfully used to guide and focus a 7-kA relativistic electron beam over distances up to 4 m. In addition, phase-mix damping of coherent, transverse beam motion has been demonstrated. A simple analytical model of the equilibrium beam profile is presented which is in reasonable agreement with the data.

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Gold disks have been irradiated with 1.06 μm laser light at intensities between 7 × 1013 and 3 × 1015 W/cm2, and pulse lengths between 200 and 1000 psec. Due to the high Z and long pulse, inverse bremsstrahlung becomes an important absorption mechanism and competes strongly with resonance absorption and stimulated scattering. In addition to measured absorptions, data on the temporal, spatial, angular, and spectral characteristics of the x-ray emission are presented. Temporally and spectrally resolved back-reflected light, and polarization-dependent sidescattered light are detected, providing estimates for the amount of stimulated scattering and of the coronal electron temperature. Inhibited electron thermal conduction and nonlocal thermodynamic equilibrium ionization physics play key roles in bringing numerical simulations of these experiments into agreement with all of the above-mentioned data.

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