Studies of plastic-ablator compressibility for direct-drive inertial confinement fusion on OMEGA.
Research paper by
S X SX Hu, V A VA Smalyuk, V N VN Goncharov, J P JP Knauer, P B PB Radha, I V IV Igumenshchev, J A JA Marozas, C C Stoeckl, B B Yaakobi, D D Shvarts, T C TC Sangster, P W PW McKenty, D D DD Meyerhofer, S S Skupsky, R L RL McCrory
The compression of planar plastic targets was studied with x-ray radiography in the range of laser intensities of I approximately 0.5 to 1.5x10(15) W/cm2 using square (low-compression) and shaped (high-compression) pulses. Two-dimensional simulations with the radiative hydrocode DRACO show good agreement with measurements at laser intensities up to I approximately 10(15) W/cm2. These results provide the first experimental evidence for low-entropy, adiabatic compression of plastic shells in the laser intensity regime relevant to direct-drive inertial confinement fusion. A density reduction near the end of the drive at a high intensity of I approximately 1.5x10(15) W/cm2 has been correlated with the hard x-ray signal caused by hot electrons from two-plasmon-decay instability.