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16 August 2000 Ablation of NIF targets and diagnostic components by high-power lasers and x rays from high-temperature plasmas
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Proceedings Volume 4065, High-Power Laser Ablation III; (2000)
Event: High-Power Laser Ablation, 2000, Santa Fe, NM, United States
The National Ignition Facility (NIF) will consist of 192 laser beams that have a total energy of up to 1.8 MJ in the third harmonic ((lambda) equals 0.35 micrometer) with the amount of second harmonic and fundamental light depending on the pulse shape. Material near best focus of the third harmonic light will be vaporized/ablated very rapidly, with a significant fraction of the laser energy converted into plasma x rays. Additional plasma x rays can come from the imploding/igniting capsule inside Inertial Confinement Fusion (ICF) hohlraums. Material from outer portions of the target, diagnostic components, first-wall material, and optical components, are ablated by the plasma x rays. Material out to a radius of order 3 cm from target center is also exposed to a significant flux of second harmonic and fundamental laser light. Ablation can accelerate the remaining material to high velocities if it has been fragmented or melted. In addition, the high velocity debris wind of the initially vaporized material pushes on the fragments/droplets and increases their velocity. The high velocity shrapnel fragments/droplets can damage the fused silica shields protecting the final optics in NIF. We discuss modeling efforts to calculate vaporization/ablation, x-ray generation, shrapnel production, and ways to mitigate damage to the shields.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
David C. Eder, Andrew T. Anderson, D. G. Braun, and Michael T. Tobin "Ablation of NIF targets and diagnostic components by high-power lasers and x rays from high-temperature plasmas", Proc. SPIE 4065, High-Power Laser Ablation III, (16 August 2000);

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