| It is shown, for the first time, that ultra-short (1ps) pulse, laser-generated Ti Kalpha radiation can be used effectively as a backlighter within a radiographic configuration in which the back-lit object is Bragg reflected and imaged onto a detector using an off-axis spherically-bent quartz crystal operating at near-normal (1°) incidence. Primarily, in this dissertation, Ti Kalpha back-lit images of six-beam driven spherical implosions of thin-walled 500mum Cu-doped CH shells are presented and analyzed to yield details of the microshell implosion dynamics and the imploded core temperatures, opacities, and radial density profiles. A comparison of these experimental results is then made with a 1-D hydrodynamic model of a similar implosion. In addition, the source Kalpha radiation generated by interaction of the ultra-short laser with thin (25 mum) titanium foils at high intensity (2 x 1016W/cm 2) is analyzed, using the radiographic image data along with data from a single hit CCD spectrometer and results from Monte-Carlo simulations, to yield estimates of laser to Kalpha energy conversion efficiencies, source brightness values and laser to electron energy conversion efficiencies. Finally, the spherically-bent crystal imager is characterized by experimental and theoretical estimates of the spatial resolution and crystal reflectivity. In particular, comparison of imager data with the data from a relatively broadband single hit spectrometer has revealed a reduction in Bragg crystal collection efficiency for high Kalpha yield. This is partially attributed to a shift in the K-shell spectrum due to Ti ionization. This novel method of x-ray radiography features high temporal and spatial resolution, high signal to noise ratio and monochromatic imaging. In addition, scalability of this technique to more energetic photon energies may prove vital for its possible future application in the diagnosis of the denser and more massive full-scale ICF capsule implosions. |
