Measurement of Spatial Temperature, Density and Mix Distributions in Igniting Plasmas on the NIF*

Now that NIF has achieved ignition and multiple experiments have achieved megajoule yields, we can study detailed plasma conditions in igniting plasmas. By combining multi-view, spectrally resolved x-ray [1] and neutron [2] imaging systems, we reconstruct time-integrated density and temperature profiles of burning hotspots near ignition. The differentially filtered x-ray imaging system constrains the electron temperature which, combined with neutron imaging, constrains the ion density without assuming that the system is isobaric [3]. With an absolutely calibrated x-ray measurement, we can extract the profile of ablator mix into the thermonuclear fuel. We can distinguish between localized mix (visible mix jets) and non-localized mix and quantify the corresponding mix mass and mix density.

[1] K. W. Wong and B. Bachmann, Rev. Sci. Instrum. 93, 073501 (2022)

[2] P. Volegov et al., J. Appl. Phys. 118, 205903 (2015)  

[3] A. Pak et al., Phys. Rev. Lett. 124, 145001 (2020)