FLASH Simulations of Laser-Driven Experiments to Investigate Heat Transport in Astrophysical Magnetized Turbulence

The role of thermal conduction in sustaining the anomalously high core temperatures observed in galaxy clusters, despite their short radiative cooling times, has been the subject of extended debate [1]. Classical Spitzer conductivity predicts a significant contribution from thermal conduction. However, astronomical observations of small-scale temperature fluctuations suggest strong suppression relative to Spitzer predictions [2], a theory supported by recent experimental work at the National Ignition Facility (NIF) [3]. The underlying mechanism responsible for the suppression remains unclear. To investigate this, high-fidelity FLASH simulations were used to design and execute an experimental campaign at the Omega Laser Facility of the Laboratory for Laser Energetics. This work leveraged the established turbulent dynamo (TDYNO) experimental platform [4], introducing heater beams to alter the temperature profile of the turbulent interaction region. The inclusion of laser heating increases the collisional mean free path to values significantly larger than the plasma Larmor radius, consequently enhancing thermal conduction suppression.

References

[1] Cowie et al., Astrophys. J. 215, 723 (1977)

[2] Markevitch et al., Astrophys. J. 586, L19 (2003)

[3] Meinecke et al., Sci. Adv. 8, eabj6799 (2022)

[4] Tzeferacos et al., Nat. Commun. 9, 591 (2018)