Characterisation and Measurement of Laser Produced Plasma Emission and Applications in Opacity Experiments

The work presented in this thesis investigates the characterization of laser produced plasmas and develops applications in opacity experiments using plasma emission as a back-lighting source. A diagnostic is developed to analyse bremsstrahlung emission from hot electrons produced in the laser plasma interaction. Combining a compensating filter technique with an x-ray diode array allows for the hot electron temperature to be deduced with good accuracy (±0.5keV). A layered target comprising 0.8um Al and 1.0um Fe is used to investigate the opacity of iron plasma. A laser of modest irradiance (~ 10^15 W cm^-2) is fired onto the aluminium surface, producing Al K-alpha emission (1.5 keV) which is used to measure the opacity of the conductively heated iron layer. The aluminium plasma is characterized using source broadened spectroscopy and continuum emission analysis. The experimental transmission data is in good agreement with 2D modelling using opacities from the Ionised Materials Package. A line focus back-lighter, produced using a high power laser system, is characterized through imaging the time and spectrally integrated emission profile of the plasma using a crossed-slit camera. The emission profile is used to infer a spatially dependant electron temperature profile. Finally, a Ti K-alpha back-lighter is used to investigate the temporal evolution of the Rayleigh-Taylor instability in a laser produced plasma. A target, seeded with an initial perturbation between layers of copper and plastic exhibited Rayleigh-Taylor growth within the first 100ps of the interaction with a growth rate of 10 ± 2 ns^-1.

Name dc:type.qualificationname

Ph.D

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of York

Year dc:date.issued

2011

Author dc:creator

• Rossall, Andrew

Advisor dc:contributor.advisor

• Tallents, Greg

Identifier

uk.bl.ethos.547348

OAI identifier oai:identifier

oai:etheses.whiterose.ac.uk:1655