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

N.C. Woolsey; J. Howe; D.M. Chambers; C. Courtois; E. Förster; C.D. Gregory; I.M. Hall; O. Renner; I. Uschmann

doi:doi:10.1051/jp4:2006133199

Numéro		J. Phys. IV France Volume 133, June 2006


Page(s)		989 - 991
DOI		https://doi.org/10.1051/jp4:2006133199
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

Abstract
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.

Possible Langmuir oscillations in the He spectral line profile

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