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P: Plasmaphysik

P 2: Heavy Ion Physics

P 2.1: Talk

Monday, March 17, 2003, 15:45–16:05, FO2

High harmonic generation from steep-gradient overdense plasmas — •Clemens Dietrich, Alexander Tarasevitch, and Dietrich von der Linde — Institute for Laser and Plasma Physics, University of Essen, 45117 Essen

The high order harmonic generation from steep-gradient overdense plasmas using high intensity fs laser pulses (1) can be qualitatively understood with the help of the simple "moving mirror" model (2). This model predicts a growth of the harmonic efficiency with the decreasing plasma density. We have performed experiments using frequency doubled fs pulses with a high contrast ratio from a TW-Ti:Sapphire laser system. The plasma density has been changed from about 2 to 100 times the critical one using different materials as targets. Surprisingly, the number of detected harmonics and their efficiency decrease for low plasma density. To explain this discrepancy we discuss an extension of the existing model, which is consistent with our experimental results and 1-dim. PIC simulations.

(1) A. Tarasevitch et al., Phys. Rev. A 62, 023816 (2000)

(2) D.von der Linde, K. Rzàzewski, Appl. Phys. B 63, 499-506 (1996)