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Title: Ion acceleration from high intensity laser plasma interactions : measurements and applications
Author: Willingale, Louise
ISNI:       0000 0004 2679 0039
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2009
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This thesis presents measurements of high energy ion beams accelerated from high intensity laser interactions, with underdense through to near critical density plasmas, and also presents an application of laser generated ion beams. The first experimental measurements of longitudinally accelerated ion beams from high intensity (-1020 Wcm-2 ) laser interactions with an underdense (0.04 ne) helium plasma are presented. The ion beam was found to have a maximum energy for He2+ of 40+3 _8 MeV, with the highest energy ions being collimated to a cone of less than 10ø. Two dimensional particle-in-cell simulations show that additional effects, due to the time varying magnetic field associated with the fast electron current, enhance the accelerating electric field and provides a focusing mechanism on the ions. Very low density foam targets were used to investigate proton acceleration from near to critical density plasmas. Experimental results show a decrease in acceleration efficiency just above the critical density. Simulations of the interactions show the proton acceleration is very sensitive to the ability of the laser to propagate through the plasma. The lowest density foams allow the best laser propagation, thus enabling proton beams to be accelerated to energy and numbers comparable to those from a solid target. The suitability of a laser generated proton beam for the measurement of self-generated magnetic fields in laser generated plasma has been investigated. The technique was then used to study a novel magnetic reconnection geometry lIsing two laser beams. Proton probing provides evidence for the formation of the reconnection layer and the corresponding instabilities.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available