Alignment of an x-ray imager line of sight in the National Ignition Facility (NIF) target chamber using a Diagnostic Instrument Manipulator (DIM) and Opposed Port Alignment System (OPAS)

摘要

The National Ignition Facility (NIF) fields multiple varieties of x-ray imaging systems used to diagnose the implosionphysics of laser-driven fusion targets. The imagers consist of time-resolved x-ray detectors coupled with a snoutassembly for spatial and/or spectral imaging. The instrument is mounted onto a cart that extends into the NIF targetchamber, placing it in close proximity to the target and aligning with a tight tolerance using the Opposed Port AlignmentSystem (OPAS). The OPAS is a modified, commercial Schmidt-Cassegrain optical telescope mounted at the targetchamber port, opposite the Diagnostic Instrument Manipulator (DIM). In this paper, the approach used to characterizeand align the x-ray imaging instruments is described. The characterization includes offline measurements of the pinholeassembly and the detector housing. Online, deviations of the DIM, as it is inserted along rails toward the target chambercenter, are characterized and related to the OPAS view. An overview of the offline measurement stations is providedalong with the process to develop the relationship between the offline alignment scopes and the OPAS as a function ofDIM insertion. The combination of these measurements is used to mathematically construct the predicted location of thex-ray imager line of sight in the OPAS image space and determine the desired pinhole location to record data on a fusionexperiment. The alignment accuracy of this approach will be discussed, as demonstrated with various x-ray instrumentsand pinhole configurations.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.