Modeling direct-drive implosions with high-Z fuel dopants with the xRAGE code

Between 2006 and 2009, several experimental campaigns at the Omega Laser Facility

studied the effect of high-Z dopants in D2 fuel of direct-drive implosions [1-4]. Results from

over 70 shots provided a record of implosion performance for different amounts of krypton,

argon, and xenon in the gas fill. Numerical approaches have been struggling to reproduce

the experimental data sets which include neutron yields, burn widths, and ion temperatures.

Here, we revisit the historic data with the multi-physics code xRAGE that is being

developed at the Los Alamos National Laboratory [5,6]. Using available and re-analyzed

experimental data, we determine how well measurements can be matched with new

simulations, testing the impact of different physics approaches to heat conductivity, non-

local thermal equilibrium (nLTE), and plasma transport. We discuss numerical

thermonuclear burn metrics such as neutron yields, bang times, and burn widths, but also

examine X-ray emission from the implosion in the form of X-ray spectral and self-emission

images.

Release number LA-UR-25-27464

[1] G. A. Kyrala et al., High Energy Density Physics 3 (2007)

[2] D. C. Wilson et al., J. Phys: Conf. Series 112 (2008)

[3] W. J. Garbett, et al., J. Phys.: Conf. Series 112 (2008)

[4] E. S. Dodd, Phys. Plasmas 18 (2012)

[5] M. Gittings et al. Comput. Sci. Disc. 1.1, 015005 (2008)

[6] B. M. Haines et al. Phys. Plasmas 29, 083901 (2022)