Electron Generations and Transportation in Fast Ignition Experiments

This thesis described the generation and transportation of hot electron in fast ignition experiments. A brief review of the background and the theory of inertial confinement fusion process are discussed. This thesis explains different schemes of fast ignition alongside the various relevant electron energy spectrum diagnostic techniques. The experiment was performed using the Vulcan PetaWatt laser at the Rutherford Appleton Laboratory. Capsules in which a re-entrant gold cone has been imbedded were involved in the experiment as targets. Gold cone targets, with a wall thickness of 20 μm and a tip thickness of 6 μm were used in the experiment. Each cone had a 40 μm diameter, approximately 1mm long copper wire attached to its tip. An electron spectrometer was used which was aligned along the axis of the wire attached to the gold cone. Results of the experiment explained the electron energy spectrum in a high energy picosecond 1.053 μm laser pulse interaction with a cone-wire target, with various degrees of laser defocusing. Diagnostics also included electron energy spectra with electron energies between 1MeV to 8MeV using image plates as detectors and found the relevant relativistic maxwellian temperature for each energy curve associated with different targets and with a different degree of laser defocusing. The results show that with an increase of defocusing of the laser, energy coupling remains the same in the cone while softening the electron energy.