J. Phys. IV France
Volume 133, June 2006
Page(s) 989 - 991
Publié en ligne 16 juin 2006
Inertial Fusion Sciences and Applications 2005
J.-C. Gauthier, et al.
J. Phys. IV France 133 (2006) 989-991

DOI: 10.1051/jp4:2006133199

Possible Langmuir oscillations in the He $\bf {\rm\beta}$ spectral line profile

N.C. Woolsey1, J. Howe1, D.M. Chambers2, C. Courtois1, E. Förster3, C.D. Gregory1, I.M. Hall1, O. Renner4 and I. Uschmann3

1  Department of Physics, University of York, Heslington, York YO10 5DD, UK
2  AWE Ltd., Aldermaston, Berkshire RG7 4PR, UK
3  Institute of Optics and Quantum Electronics, University of Jena, 07743 Jena, Germany
4  Institute of Physics, Academy of Sciences CR, 18221 Prague, Czech Republic

A 3.4 ps duration, high-repetition rate laser is used to create an aluminium ablation plasma at intensities between 1015 W/cm2 and 1017 W/cm2. K-shell emission is observed from the target surface and several 100 $\mu $m in to the plume. High resolution, spatial resolved measurements of the He$\beta $ (1s3p - 1s2), He$\gamma $ (1s4p - 1s2), He$\delta $ (1s5p - 1s2) and He $\varepsilon $ (1s6p - 1s2) transitions are obtained using a highly dispersive toroidal crystal spectrometer coupled to a large area charged-coupled device. This data shows unusual intensity modulations on He$\beta $ transitions. These oscillations are observed to 50 $\mu $m above the target and are found to be reproducible, and the intensity of the modulations is laser irradiance dependent.

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