Lawrence Livermore National Laboratory


New Software Tool Speeds NIF Target Alignment

One of the most demanding aspects of preparing NIF for an experiment is precisely aligning NIF’s 192 laser beams and the experiment’s target to tolerances measured in a few microns (millionths of a meter). To analyze the experiment’s results, a variety of target diagnostics, including optical, x-ray, and nuclear diagnostics, also must be positioned accurately and reliably within tight specifications to ensure that good data are acquired.

Target alignment typically involves the use of a suite of optical alignment systems that provide multiple camera views of the target; Beam Control System (BCS) operators measure the location of the target fiducials (reference points) in each camera view and use a spreadsheet to calculate the correct orientation and positioning of the target.

Now, thanks to the development of a new software tool called the Target Alignment Assistant Tool (TAAT), the time and effort involved in that painstaking process have been reduced substantially by automating many of the steps. “TAAT is a software interface that manages the views and measurements to greatly streamline the process,” said NIF&PS physicist Pascale Di Nicola, a member of the Alignment Integrated Project Team. “We can use it for alignment of any target positioner as well as for diagnostics. TAAT reduces the number of simple operator actions to align a target by a factor of two, and the possibility of human errors, especially for operators in training, to zero.”

Operator Aligns TargetBeam Control Operator Marlos Hickam aligns a high-foot deuterium-tritium target using the Target Alignment Assistant Tool (TAAT). The new system saves time and also increases accuracy of target alignment compared to the manual procedure.

Based on a concept described in July of last year by NIF&PS Senior Target Area Scientist Dan Kalantar, TAAT was developed by Kalantar and Integrated Computer Control System (ICCS) team members Jorge Castro Morales, Valier Pacheu, and Rick Wilson in just a few weeks. Di Nicola and Jared Okui translated the three main alignment procedures into Excel scripts the Java software would be able to interpret, and Tom Zobrist arranged the operations training and briefings related to TAAT. The system was successfully tested on Sept. 3 in the NIF cryogenic target positioner.

Di Nicola said TAAT’s intuitive nature allows for rapid training of the beam control operators, and the tool has been used for shot operations since Oct. 21. An experiment on Nov. 6 was performed 10 hours ahead of schedule thanks in part to the use of TAAT.

Operator Checks Target Alignment; Comparison of Target Alignment Times (Left) Cryogenic Systems Operator Dan Burmann checks the alignment of a double-foil target on the NIF target positioner for an Oct. 21 collisionless shock experiment. The two deuterated targets create high-speed counter-propagating plasma flows that enable the study of self-generated magnetic fields. The green plastic caps are unconverted-light shields. (Right) The Oct. 21 experiment was the first time the Beam Control System alignment team used the new Target Alignment Assistant Tool for a production shot, aligning the target in just 27 minutes (red bars). Manual alignment for a previous collisionless shock experiment in July took more than an hour (blue bars).

The tool provides the appropriate images and reference features and locations to the operator and captures their interactive measurements. It then directly couples the measurements to the calculation and positioner moves, and progresses through the process once documented tolerances are reached.

“Along with saving time, TAAT eliminates a lot of mouse clicking and typing for the operators, creating a less stressful environment and making it easier for them to focus on their work,” Di Nicola said. “After using it for a few months, the operators have been proposing a lot of very sensible improvements, some of which have already been implemented. It does 90 percent of what we want, and now we’re working on the last 10 percent.”

Members of the TAAT TeamMembers of the TAAT Team (from left): Jared Okui, Jorge Castro Morales, Valier Pacheu, Pascale Di Nicola, Rick Wilson, Tom Zobrist, and Dan Kalantar.