Laser-plasma interaction generated proton isochoric heating and focusing

Fast ignition (FI) by laser-generated, ballistically focused protons is a new proposed alternative to the original concept of FI by laser-generated relativistic electrons. The key potential advantage in using proton FI lies in less-complex energy transport into dense plasma. Because of the high mass ratio of proton over electron, protons can maintain a stiff trace while traversing dense plasma.;Another novel technique for detecting both focal size and focal plane position of protons with different energy is proposed in this dissertation. In this technique, radiochromic films (RCF) are used to picture Cu mesh images projected by focused protons. The RCF consists of a series of films which stops different energy protons. By studying the magnifications and using the proportionalities of similar triangles, proton beam's focal plane position and focal size can be determined. The focal plane position calculated through this method is compared with the value derived from XUV images under the same condition in this dissertation.;The requirement for proton FI is to heat D-T fuel with total 18 k3 proton energy at 3 MeV in 10 ps over 30 mum diameter. Due to the generation mechanism, a concave spherical target surface is used to focus protons. The focal plane position and focal size are currently under study. In this dissertation, for the first time, the blackbody radiation from the proton-heated target is used for the temperature measurement. Through the temperature measurement, focal plane position can be derived to be the location where the target's rear surface temperature peaks. In the experiments, the heated target's rear surface is reflected and imaged onto a detector using a spherically-bent multilayer mirror operating at near-normal incidence angle and a flat 45° turning mirror. Two sets of multilayer mirrors are precisely fabricated to reflect photons with energy of 68 eV and 256 eV. The XUV images of Al and polymer slabs at different separations from hemisphere are captured and analyzed to display the results of focal plane position for protons with different energy.