Enhanced Bremsstrahlung Emission in Intense Laser-Cluster Interactions*

What dynamics ensues when a sub-picosecond, 248 nm, pulse of laser light interacts with a xenon cluster of 10-10$^{4}$ atoms at intensities $>$10$^{19}$ W/cm$^{2}$? Measurements in such experiments are difficult to make. However, in them [1], two features stood out. One, a 2 mm long, 1-3 $\mu $m diameter channel of self-focused laser light was formed, and two, amplification of $\approx $2.8 {\AA} x-radiation along the channel was observed. A model that would generate the population inversions needed to produce the observed amplifications was recently constructed [2]. It assumed that inner-shell n=2 holes were being generated through inner-shell photoionizations that came about through bremsstrahlung emissions that were being greatly enhanced in the presence of intense laser fields ($>$10$^{19}$ W/cm$^{2})$. In this talk, we present results from quantum electrodynamics calculations [3] that support the production of such enhancements.\\[4pt] [1] Borisov A. B., \textit{et. al.}, J. Phys. B, \textbf{41},105602 (2008). [2] Petrova Tz. B., \textit{et. al.}, J. Phys. B, \textbf{43}, 025601 (2010); \textbf{44}, 125601 (2011). [3] Lebed A. A. and Roshchupkin S. P., Phys. Rev. A, \textbf{81}, 033413 (2010).