J.-C. Gauthier, et al.
J. Phys. IV France 133 (2006) 989-991
Possible Langmuir oscillations in the He spectral line profileN.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 m in to the plume. High resolution, spatial resolved measurements of the He (1s3p - 1s2), He (1s4p - 1s2), He (1s5p - 1s2) and He (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 transitions. These oscillations are observed to 50 m above the target and are found to be reproducible, and the intensity of the modulations is laser irradiance dependent.
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