Target imaging and backlighting diagnosis

B. Yaakobi, D. Shvarts, F. J. Marshall, R. Epstein, Q. Su
1995 Review of Scientific Instruments  
The case of an x-ray backlighting image of a CH-shell target imploded by the OMEGA Upgrade laser system has been calculated and analyzed. The goal is to obtain information on the conditions at peak compression, where the experimental constraints due to target self-emission and required spatial resolution are maximal. Particular attention is devoted to the problem of discriminating against the target self-emission. It is shown that this can be done by obtaining a monochromatic image at a single
more » ... image at a single spectral line emitted by the backlighter. Additionally, the target self-emission image has useful signatures, which can be studied with or without a backlighter. Two experimental configurations for monochromatic imaging are discussed: (a) an x-ray microscope with a flat crystal monochromator, and (b) pinhole imaging in conjunction with a curved crystal monochromator. Useful images are obtained with simple (undoped) CH-shell targets and without the need for a short-pulse backlighter beam. Case Study of Experimental Parameters We discuss the feasibility of backlighting experiments, using the LILAC code for simulating a candidate OMEGA Upgrade target. The target is a polymer shell of 940-ym diam and 30-ym thickness, filled with 80 atm DT gas, and imploded by a trapezoidal pulse. The pulse rises linearly over a 0.1-ns period to 13.5 TW, then remains constant for 2.2 ns, before dropping linearly over a 0.1-ns period. LILAC results were used for simulating the expected backlight image for this test shot. Figure 58 .1 shows the density and electron-temperature LLE Review. Volume 58
doi:10.1063/1.1146426 fatcat:523fwe6t3fcjpitftozpypnd4u