Session YO6: Magneto-Inertial Fusion

Quantification of MagLIF implosion morphology using the Mallat Scattering Transformation

The morphology of the stagnated plasma resulting from  Magnetized Liner Inertial Fusion (MagLIF) is measured by imaging the self-emission x-rays coming from the multi-keV plasma, and the morphology of the imploding liner is measured by radiographs.  Equivalent diagnostic response can be derived from integrated rad-hydro simulations from programs such as Hydra and Gorgon.  There have been only limited quantitative ways to compare the image morphology, that is the texture, of simulations and experiments.  We have developed a metric of image morphology based on the Mallat Scattering Transformation, a transformation that has proved to be effective at distinguishing textures, sounds, and written characters.  This metric has demonstrated excellent performance in classifying ensembles of synthetic stagnations images and radiographs.  A good regression of the scattering coefficients to the parameters used to generate the synthetic images was found.  Finally, the metric has been used to quantitatively compare simulations to experimental images, and to estimate the parameters of the images with uncertainty.   

Monitoring preheat performance in Magnetized Liner Inertial Fusion experiments with stimulated Raman and Brillouin backscatter measurements

The Magnetized Liner Inertial Fusion (MagLIF) platform requires efficient coupling of laser energy to the underdense D₂ fuel to produce significant fusion yield. Although laser-plasma instabilities typically constitute undesirable loss mechanisms of laser energy, their signatures help monitor the performance of laser preheat in MagLIF experiments. We present time-resolved spectral measurements of stimulated Raman and Brillouin backscatter from preheat experiments conducted on both the Z Machine and the PECOS target chamber at SNL. The measurements exhibit time-dependent signatures of the density and temperature of the laser entrance window and heated plasma channel produced in the gas by the Z Beamlet laser. The measurements demonstrate significant differences in the laser-plasma interactions when changing the laser pulse shape and beam profile.   

Numerical studies on the radiation uniformity of quasi-spherical Z-pinch dynamic hohlraum using code MULTI-2D

Z-pinch driven fusion is a promising approach for the realization of fusion energy due to its high energy conversion efficiency and robust ignition scheme. Typical Z-pinch dynamic hohlraum driven fusion involves a spherical pellet imploded by the x-ray radiation field inside the hohlraum. When the hohlraum is created by the collision of a cylindrical wire-array and plastic foam, the fronts of the shock and thermal wave propagating towards the pellet are cylindrical as well, making the pellet tend to be ablated and compressed asymmetrically. With the help of quasi-spherical implosion, both the shock front and thermal wave front can be modulated, so that the radiation uniformity around the pellet can be improved significantly. Besides, a higher radiation temperature can be achieved because of the three-dimensional compression in quasi-spherical Z-pinch dynamic hohlraum. In this report, we present simulation results about the hohlraum radiation uniformity with/without a pellet inside on Julong-I facility (~8MA). Simulations are conducted using the one-group, two-temperature radiation magneto-hydrodynamic code MULTI-2D.