A study of the XUV flux emission from laser-plasmas using a multilayer monochromator
Collins, M. J
(1994)
A study of the XUV flux emission from laser-plasmas using a multilayer monochromator.
Master of Science thesis, Dublin City University.
When the output of a high-power laser is focussed onto the surface of a solid target, a localised and short-lived plasma is formed which is charactensed by high electron densities and temperatures As a result, such plasmas radiate predominantly in the extreme UV and x-ray spectral regions Results from a study on the dependence of extreme ultraviolet (XUV) emission from plasmas created with a conventional Nd YAG laser (500 mJ, 10 ns) on target elements from carbon through lead are presented. A complete descnption of the XUV flux measurement system is given. For a number of elements, spectral measurements in the energy region of interest were recorded using a 2 2 m grazing incidence multichannel photoelectnc spectrometer. These spectra are used to generate a complementary atomic-number dependence which is compared with that yielded from the flux measurement system.
The XUV emission spectra from plasmas of cobalt through zinc are measured. The corresponding predominant ion stages and electron temperatures are inferred from these spectra. Emission spectra were previously recorded on a 2 m photographic grazing incidence spectrograph As a result of this study, new lines from the 3s23pn -> 3s23pn_14s transitions arrays, for n = 1, 3 and 4, have been classified.
Finally, following recent reports on sub-nanosecond double-pulsed laserproduced plasmas yielding enhanced x-ray emission, i we have performed a corresponding study with our table-top laser source. Results from measurements of the XUV dependence on time-delay, energy ratio and overlap between the laser pulses are reported. We have observed up to a 40% increase in the XUV flux, under certain conditions, over single pulse produced plasmas of the same total laser pulse energy.