Z-Pinch-Driven Fast Ignition Fusion

Abstract

Fast ignition using pulsed-power drivers combines the efficient production of X-rays to drive fusion fuel assembly with precise ultraintense laser pulses for fuel ignition. Z-pinches convert electrical energy into thermal X-ray energy with high efficiency, which makes them attractive drivers for indirect-drive fuel assembly. Currently, experiments use the Z-pinch vacuum hohlraum, in which the Z-pinch heats a hohlraum that reemits thermal X-rays to drive the capsule. Surface-guided hemispherical capsule implosion experiments in Z-pinch vacuum hohlraums are in progress to study energetics, symmetry control, and pulse shaping. Simulations including radiation asymmetry and glide-plane physics have been performed to optimize the imploded fuel. Higher density capsule implosions at a given driver energy may be possible using the Z-pinch dynamic hohlraum, in which the Z-pinch plasma itself creates the hohlraum. Capsule and hohlraum designs for both vacuum and dynamic hohlraum sources are in progress, including liquid cryogenic fuel capsules. Analytic models for D-T fuel heating and burn have been developed for scoping purposes and breakeven scaling. Implicit particle-in-cell modeling of the interaction of laser-produced energetic particles with calculated fuel configurations demonstrates that details of the entire fuel/glide material density profile significantly affect the calculated energy deposition and thus the ignition requirements.