Energy gain of wetted-foam implosions with auxiliary heating for inertial fusion studies
Plasma Physics and Controlled Fusion IOP Publishing 66:2 (2024) 025005
Energy gain of wetted-foam implosions with auxiliary heating for inertial fusion studies
Plasma Physics and Controlled Fusion IOP Publishing 66:2 (2023) 025005
Abstract:
Low convergence ratio implosions (where wetted-foam layers are used to limit capsule convergence, achieving improved robustness to instability growth) and auxiliary heating (where electron beams are used to provide collisionless heating of a hotspot) are two promising techniques that are being explored for inertial fusion energy applications. In this paper, a new analytic study is presented to understand and predict the performance of these implosions. Firstly, conventional gain models are adapted to produce gain curves for fixed convergence ratios, which are shown to well-describe previously simulated results. Secondly, auxiliary heating is demonstrated to be well understood and interpreted through the burn-up fraction of the deuterium-tritium fuel, with the gradient of burn-up with respect to burn-averaged temperature shown to provide good qualitative predictions of the effectiveness of this technique for a given implosion. Simulations of auxiliary heating for a range of implosions are presented in support of this and demonstrate that this heating can have significant benefit for high gain implosions, being most effective when the burn-averaged temperature is between 5 and 20 keV.Measuring spatio-temporal couplings using modal spatio-spectral wavefront retrieval
Optics Express Optical Society of America 31:12 (2023) 19733-19745
Abstract:
Knowledge of spatio-temporal couplings such as pulse-front tilt or curvature is important to determine the focused intensity of high-power lasers. Common techniques to diagnose these couplings are either qualitative or require hundreds of measurements. Here we present both a new algorithm for retrieving spatio-temporal couplings, as well as novel experimental implementations. Our method is based on the expression of the spatio-spectral phase in terms of a Zernike-Taylor basis, allowing us to directly quantify the coefficients for common spatio-temporal couplings. We take advantage of this method to perform quantitative measurements using a simple experimental setup, consisting of different bandpass filters in front of a Shack-Hartmann wavefront sensor. This fast acquisition of laser couplings using narrowband filters, abbreviated FALCON, is easy and cheap to implement in existing facilities. To this end, we present a measurement of spatio-temporal couplings at the ATLAS-3000 petawatt laser using our technique.Probing bulk electron temperature via x-ray emission in a solid density plasma
Plasma Physics and Controlled Fusion IOP Publishing 65:4 (2023) 045005
Hyperspectral compressive wavefront sensing
High Power Laser Science and Engineering Cambridge University Press 11 (2023) e32