Evidence for ultra-fast heating in intense-laser irradiated reduced-mass targets
Abstract
We report on an experiment irradiating individual argon droplets of 20 μm diameter with laser pulses of several Joule energy at intensities of 1019 W/cm2. K-shell emission spectroscopy was employed to determine the hot electron energy fraction and the time-integrated charge-state distribution. Spectral fitting indicates that bulk temperatures up to 160 eV are reached. Modelling of the hot-electron relaxation and generation of K-shell emission with collisional hot-electron stopping only is incompatible with the experimental results, and the data suggest an additional ultra-fast (sub-ps) heating contribution. For example, including resistive heating in the modelling yields a much better agreement with the observed final bulk temperature and qualitatively reproduces the observed charge state distribution.
- Publication:
-
Physics of Plasmas
- Pub Date:
- December 2012
- DOI:
- 10.1063/1.4772773
- Bibcode:
- 2012PhPl...19l2708N
- Keywords:
-
- argon;
- drops;
- hot carriers;
- plasma collision processes;
- plasma heating by laser;
- plasma light propagation;
- plasma temperature;
- 52.50.Jm;
- 47.55.D-;
- 52.20.Fs;
- 52.25.Os;
- 52.38.Dx;
- Plasma production and heating by laser beams;
- Drops and bubbles;
- Electron collisions;
- Emission absorption and scattering of electromagnetic radiation;
- Laser light absorption in plasmas