Suprathermal electrons generated by the two-plasmon-decay instability in gas-filled Hohlraums

For the first time a burst of suprathermal electrons is observed from the exploding laser-entrance-hole window of gas-filled Hohlraums driven with 13.5 kJ of 351 nm laser light. The two-plasmon-decay instability appears to produce up to 20 J of hot electrons with T hot ∼ 75 keV at early times and has a sharp laser-intensity threshold between 0.3 and 0.5 × 10 15 W / cm 2 . The observed threshold can be exploited to mitigate preheat by window hot electrons in ignition Hohlraums for the National Ignition Facility and achieve high-density, high-pressure conditions in indirect drive implosions.