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(IFP/08) Hot Superdense Plasmas and Fast Electron Jets from Intense Femtosecond Laser Pulses

K. J. Witte¹⁾, U. Andiel¹⁾, K. Eidmann¹⁾, E. Fill¹⁾, C. Gahn¹⁾, I. Golovski²⁾, D. Habs³⁾, R. Mancini²⁾, J. Meyer-ter-Vehn¹⁾, G. Pretzler¹⁾, A. Pukhov¹⁾, R. Rix¹⁾, T. Schlegel¹⁾, and G. Tsakiris^1)
 
1) Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching
²⁾ Department of Physics, University of Nevada, Reno NV 89557-0058, USA
³⁾ Sektion Physik, LMU München, Am Coulombwall 1, D-85748 Garching

Abstract.  With high-contrast light pulses of $\leq$200-fs duration focused to intensities of $\geq$ 10¹⁸W/cm², strongly coupled plasmas at solid state density and temperatures of a few 100eV can be generated. These plasmas are similar to those currently achievable only in indirectly imploded gas-filled microspheres during stagnation. The table-top size and high-repetition rate of the lasers producing these ultra-short pulses provided in our case by the 2-TW facility ATLAS allow to systematically investigate the basic features of these plasmas. First the mechanism of the dense-plasma generation is discussed. This is based on hydrocode and PIC simulations as well as on measurements of light absorption and the energy transport into the target. We then present spectrally and time-resolved measurements of the K-shell emission from aluminum targets. By fitting synthetic spectra obtained from code simulations to the experimental ones, it can be inferred that the plasma has an electron density of $\sim$ 10²⁴/cm³ and a temperature of $\sim$ 300eV. In the fast-ignitor concept, a laser-generated electron jet is expected to ignite the central spot of the compressed target. Using ATLAS pulses focused to on-target intensities of 10¹⁸ - 10¹⁹W/cm², we investigate the e-beam generation mechanism in preformed under-dense plasmas. A new fast-electron acceleration mechanism is identified.

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