South pole bang-time diagnostic on the National Ignition Facility

• Main Authors: MacPhee, A, Edgell, D, Bradley, D K, Bond, E J, Burns, S, Callahan, D A, Celeste, J, Kimbrough, J, Mackinnon, A J, Magoon, J, Eckart, M J, Glebov, V, Hey, D, Lacielle, G, Kilkenny, J, Parker, J, Sangster, T C, Shoup, M J, Stoeckl, C, Thomas, T
• Language: unknown
• Published: 2021
• Subjects: 36 MATERIALS SCIENCE; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 42 ENGINEERING; ACCURACY; CHEMICAL VAPOR DEPOSITION; COMPRESSION; DIAMONDS; GRAPHITE; IMPLOSIONS; LASERS; MIRRORS; MONOCHROMATORS; PLASMA DIAGNOSTICS; REMOVAL; RESPONSE FUNCTIONS; US NATIONAL IGNITION FACILITY; South Pole; South pole
• Online Access: http://www.osti.gov/servlets/purl/1043656; https://www.osti.gov/biblio/1043656

The south pole bang-time (SPBT) diagnostic views National Ignition Facility (NIF) implosions through the lower hohlraum laser entrance hole to measure the time of peak x-ray emission (peak compression) in indirect drive implosions. Five chemical-vapor-deposition (CVD) diamond photoconductive detectors (PCD's) with different filtrations and sensitivities record the time-varying x rays emitted by the target. Wavelength-selecting highly oriented pyrolytic graphite (HOPG) crystal mirror monochromators increase the x-ray signal-to-background ratio by filtering for 11-keV emission. Diagnostic timing and the in-situ temporal instrument response function are determined from laser impulse shots on the NIF. After signal deconvolution and background removal, the bang time is determined to 45-ps accuracy. The x-ray 'yield' (mJ/sr/keV at 11 keV) is determined from the total area under the peak.