LLNL, Livermore, California, USA
The programmable spatial shaper (PSS) within the National Ignition Facility (NIF) reduces energy on isolated optic flaws in order to lower the optics maintenance costs. This will be accomplished by using a closed-loop system for determining the optimal liquid-crystal-based spatial light pattern for beamshaping and placement of variable transmission blockers. A stand-alone prototype was developed and successfully run in a lab environment as well as on a single quad of NIF lasers following a temporary hardware reconfiguration required to support the test. Several challenges exist in directly integrating the C-based PSS engine written by an independent team into the Integrated Computer Control System (ICCS) for proof on concept on all 48 NIF laser quads. ICCS is a large-scale data-driven distributed control system written primarily in Java using CORBA to interact with +60K control points. The project plan and software design needed to specifically address the engine interface specification, configuration management, reversion plan for the existing 0% transmission blocker capability, and a multi-phase integration and demonstration schedule.
LLNL, Livermore, California, USA
The Disposable Debris-Shield (DDS) Attenuation Tool is software that leverages Automatic Alignment image analysis results and takes advantage of the DDS motorized insertion and removal to compute the in-situ transmission of the 192 NIF DDS. The NIF employs glass DDS to protect the final optics from debris and shrapnel generated by the laser-target interaction. Each DDS transmission must be closely monitored and replaced when its physical characteristics impact laser performance. The tool was developed to calculate the transmission by obtaining the total pixel intensity of acquired images with the debris shield inserted and removed. These total intensities existed in the Automatic Alignment image processing algorithms. The tool uses this data, adding the capability to specify DDS to test, moves the DDS, performs calculations, and saves data to an output file. It operates on all 192 beams of the NIF in parallel, and has shown a discrepancy between laser predictive models and actual. As qualification the transmission of new DDS were tested, with known transmissions supplied by the vendor. This demonstrated the tool capable of measuring in-situ DDS transmission to better than 0.5% rms.
LLNL, Livermore, California, USA
The Virtual Beam Line (VBL) code is essential to operate, maintain and validate the design of laser components to meet the performance goals at Lawrence Livermore National Laboratory’s National Ignition Facility (NIF). The NIF relies upon the Laser Performance Operations Model (LPOM), whose physics engine is the Virtual Beam Line (VBL) code, to automate the setup of the laser by simulating the laser energetics of the as-built system. VBL simulates paraxial beam propagation, amplification, aberration and modulation, nonlinear self-focusing and focal behavior. Each of the NIF’s 192 beam lines are modeled in parallel on the LPOM Linux compute cluster during shot setup and validation. NIF achieved a record 1.8 MJ shot in July 2012, and LPOM (with VBL) was key to achieving the requested pulse shape. We will discuss some examples of how the VBL physics code is used to model the laser phenomena and operate the NIF laser system.
