Investigating at-scale MagIF preheat on the NIF

Recent experiments with CH and D2-filled gas pipe targets at the NIF have continued to investigate laser coupling at parameters relevant to 40+ MA MagLIF designs. At present, ~20 kJ energy coupling has been achieved at fill densities ~5 mg/cc in 1 cm-long CH-gas-filled targets. One of the most significant uncertainties in the coupling is the energy deposition into the tube entrance window material, which is predicted in simulations to be of order ~few kJ but which is difficult to measure directly. By employing the NIF Visar system to measure the shock strength when the heated plasma reaches the wall of the target, the total energy deposited into the gas can be accurately determined. These measurements are compared with x-ray imaging and time-resolved measurements of the laser propagation through the target, and to 2D and 3D simulations.

 

This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.