Speaker: Farhat Beg (UCSD)
Title: Proton Heating in Integrated Proton Fast Ignition Experiments
Abstract: Proton fast ignition (PFI) is an alternative inertial confinement fusion (ICF) concept that promises high gain suitable for inertial fusion energy applications. In this concept, a short-pulse, high-intensity laser is used to generate an energetic proton beam that efficiently couples’ energy into a pre-compressed fuel assembly. This enables ignition conditions to be reached with less stringent symmetry and driver energy requirements than in the conventional hot-spot approach.
We report on the first integrated PFI campaign at the Omega Laser Facility that included both the compression and ignition phases to measure the temperature increase in the compressed core due to proton heating. In the recent experiment, we increased the short-pulse laser intensity by a factor of 6 and observed a 3× improvement in the proton maximum cutoff energy and a 6× enhancement in the yield of >10 MeV protons that primarily heat the core. X-ray spectroscopy data reveal dominant Heα and Heβ features consistent with heating of the compressed core. Implosion trajectories obtained from radiation-hydrodynamics simulations agree well with experiments and indicate an implosion velocity of approximately 70 km/s for an implosion energy of 10 kJ. A detailed comparison of the measured implosion trajectories, velocities, and proton energy spectra with radiation-hydrodynamics and PIC simulations will be presented.