Software Design For High-Speed Shock-Driven Experiments

The Extreme Fluids Team of Physics Division, P-23, specializes in high spatial and temporal resolution experimental diagnostics.  The team uses lasers to illuminate high-speed flows, and digital cameras to record scattered light.  A new facility has been built by the team over the past year, called the Vertical Shock Tube (VST).  The VST was built to study shock-driven mixing in a variable-density flow.  Because of the high-speed nature of the shock-driven flows being studied at the VST, high precision is needed in the timing of the lasers and cameras.  This involves the use of digital signal generators that are controlled by a data acquisition computer running LabVIEW software.  This allows microsecond accuracy in equipment timing.  In addition to timing accuracy, precision and accuracy in the placement of the equipment is needed for spatial accuracy of measurements of both velocity and density fields.  This project’s focus is on developing software to control the digital delay generators’ signals to the diagnostic equipment.  A special language for instrumentation programming, called VISA, was used as an interface between LabVIEW and the delay generators.  The LabVIEW software is being designed to optimize the user interface to make programming of the VST data acquisition as simple as possible for the experimentalists.  The goal of the project is to have a working interface for experiments that controls the position and timing of the cameras and lasers and that is compatible with the other subprograms being used to control other elements of the operation of the VST.