Investigating at-scale MagLIF preheat on the NIF

Recent experiments with D2-filled gas pipe targets at the NIF have continued to investigate laser preheating at parameters relevant to 40+ MA MagLIF designs. The experiments span a range of 3.2-4.8 mg/cc fill densities, and measure time-resolved laser propagation and burnthrough in 1-1.6 cm-long targets. 1D predictions of laser absorption indicate that the coupling scales with laser spot size; this has been tested by separating the four drive beams to increase the effective spot size while still employing the standard NIF phase plates. Energy coupling increases close to predictions, though the scaling with electron density deviates from the prediction. The results are also compared with 2D HYDRA 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.