| We are becoming dependent on energy more today than we were a century ago, and with increasing world population and booming economies, sooner or later our energy sources will be exhausted. Moreover, our economy and welfare strongly depends on foreign oil and in the shadow of political uncertainties, there is an urgent need for a reliable, safe, and cheap energy source. Thermonuclear fusion, if achieved, is that source of energy which not only will satisfy our demand for today but also for centuries to come. Today, there are two major approaches to achieve fusion: magnetic confinement fusion (MFE) and inertial confinement fusion (ICF). This dissertation explores inertial confinement fusion using the fast ignition concept. Unlike the conventional approach where the same laser is used for compression and ignition, in fast ignition separate laser beams are used. This dissertation addresses three important topics to fast ignition inertial confinement fusion. These are laser-to-electron coupling efficiency, laser-generated electron beam transport, and the associated isochoric heating.; First, an integrated fast ignition experiment is carried out with 0.9 kJ of energy in the compression beam and 70 J in the ignition beam. Measurements of absolute K-alpha yield from the imploded core revealed that 17% of the laser energy is coupled to the suprathermal electrons. Modeling of the transport of these electrons and the associated isochoric heating, with the previously determined laser-to-electron conversion efficiency, showed a maximum target temperature of 166 eV at the front where the electron flux is higher. The contribution of the potential, induced by charge separation, in opposing the motion of the electrons was moderate. Second, temperature sensitivity of Cu K-alpha imaging efficiency using a spherical Bragg reflecting crystal is investigated. It was found that due to the shifting and broadening of the K-alpha line, with increasing temperature, both the brightness and the pattern of K-alpha intensity were affected. Finally, x-ray spectroscopy of a 500 J 0.7 ps laser-solid interactions showed a formation of a hot surface layer at the front of the target. |
