skip to main content

SciTech ConnectSciTech Connect

Title: A Robust In-Situ Warp-Correction Algorithm For VISAR Streak Camera Data at the National Ignition Facility

The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a 192-beam pulsed laser system for high-energy-density physics experiments. Sophisticated diagnostics have been designed around key performance metrics to achieve ignition. The Velocity Interferometer System for Any Reflector (VISAR) is the primary diagnostic for measuring the timing of shocks induced into an ignition capsule. The VISAR system utilizes three streak cameras; these streak cameras are inherently nonlinear and require warp corrections to remove these nonlinear effects. A detailed calibration procedure has been developed with National Security Technologies (NSTec) and applied to the camera correction analysis in production. However, the camera nonlinearities drift over time, affecting the performance of this method. An in-situ fiber array is used to inject a comb of pulses to generate a calibration correction in order to meet the timing accuracy requirements of VISAR. We develop a robust algorithm for the analysis of the comb calibration images to generate the warp correction that is then applied to the data images. Our algorithm utilizes the method of thin-plate splines (TPS) to model the complex nonlinear distortions in the streak camera data. In this paper, we focus on the theory and implementation of the TPS warp-correction algorithmmore » for the use in a production environment.« less
Authors:
 [1] ;  [2] ;  [2] ;  [2]
  1. Univ. of California, Santa Cruz, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
OSTI Identifier:
1179398
Report Number(s):
LLNL-CONF--666164
TRN: US1600146
DOE Contract Number:
AC52-07NA27344
Resource Type:
Conference
Resource Relation:
Conference: SPIE Photonic West 2015, San Francisco, CA (United States), 7-12 Feb 2015
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 97 MATHEMATICS AND COMPUTING; STREAK CAMERAS; ALGORITHMS; CORRECTIONS; US NATIONAL IGNITION FACILITY; NONLINEAR PROBLEMS; CALIBRATION; IMAGES; INTERFEROMETERS; PERFORMANCE; BEAM PULSERS; ACCURACY; IMPLEMENTATION; SHOCK WAVS; PULSES; VELOCITY