Exploration of the physics between colliding expanding gold and carbon plasmas in the context of hohlraum dynamics

Indirect-drive uses a laser-irradiated hohlraum to uniformly irradiate a fusion capsule with soft-x-rays. Deviations in irradiation symmetry promote asymmetrical capsule collapse which reduces the fusion yield. Capsule performance is tied to understanding the complex, underlying hohlraum physics. Absorption of laser and x-ray radiation creates plasma flows, which refract and absorb incident laser beams and alter the implosion symmetry. Plasma flows can also create conditions for laser plasma instabilities. We present results from quasi-one dimensional experiments probing the interaction of expanding carbon and gold plasmas.

A laser-irradiated, planar, thin, gold foil provides a source of soft x-rays and a flow of high-Z plasma similar to that of a hohlraum. A carbon-foam sphere with a density of ~130-mg/cc approximates the capsule ablator. Radiographic measurements, HYADES simulations and a simple model show reasonable agreement.

This work is funded by the U.S. DOE NNSA Center of Excellence under Cooperative Agreement number DE- NA0003869, and the NLUF Program, grant number DE-NA0002719, and through the LLE, University of Rochester by the NNSA/OICF under Cooperative Agreement No. DE-NA0003856.