Berlin 2005 – scientific programme
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SYLP: Relativistische Laser-Plasma-Physik
SYLP 3: Poster zum Symposium Relativistische Laser-Plasma-Physik
SYLP 3.9: Poster
Saturday, March 5, 2005, 10:00–17:00, HU Senatssaal
Observation of laser-driven filamented electron beams by means of Cerenkov radiation — •J. Stein1,2, E. Fill1, J. Meyer-ter-Vehn1, U. Schramm2, D. Habs2, and K. Witte1 — 1Max-Planck-Institut für Quantenoptik, Garching — 2Ludwig-Maximilians-Universität München
Cerenkov radiation [1] has been used to investigate electron beam filamentation in solids with high spatial resolution of 4 µ m. The patterns show strongly filamented ring-like structures of 300 µ m diameter, observed at the rear side of thin foils irradiated with 1019 W/cm2 pulses. The Cerenkov medium (50 µ m) emitting visible light detected by means of a fast gated CCD. It is proportional to the thickness of the Cerenkov medium and to the number of electrons with energies of about 200 keV. We interpret the results as evidence for the decay of a cylindrical electron beam, when passing through dense plasma, due to return currents and Weibel instability [2,3]. After passing several micrometers in matter the filamentes have the tendency to coalesce with each other leading to strong anomalous stopping of the beam exceeding Coulomb stopping by orders of magnitude. [1] F. Brandl, et al., Europhys. Lett. 61, 632 (2003) [2] M. Honda, et al. , Phys. Rev. Lett. 85, 2128 (2000) [3] Y. Sentoku, et al., Phys. Rev. Lett. 90, 155001 (2003)