Speaker
Grégoire Varillon
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.2018.pdf
Investigation of supersonic heat-conductivity linear waves
in ablation flows
G. Varillon1,2 , J.M. Clarisse1 , A. Couairon2
1 CEA, DAM, DIF, F-91297, Arpajon, France
2 CPHT, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France
Ablation flows relative to inertial confinement fusion (ICF) are well described by gas dynam-
ics equations with non-linear radiative heat-conduction. Standard descriptions often assume an
isothermal conduction region [1, 2]. However a local analysis in terms of linear propagating
waves reveals that temperature stratification in this region gives rise to supersonic wave veloc-
ity as a consequence of nonlinear heat-conduction [3]. Such behaviours arise in the case of high
heat propagation regimes. These supersonic ‘heat-conductivity’ waves are associated with heat
flux perturbation inhomogeneities that convey perturbation inhomogeneities in temperature and
density. These latters may trigger radiative heat transport instabilities [4] and destabilize the
ablation front.
In the present work, we conduct numerical computations of linear perturbations in ablation
flows. We drop the local hypothesis to address non-uniform and non-stationary realistic ablation
flows. The entire deflagration region is modeled, and damping effects due to heat diffusion are
exactly taken into account by contrast to [3]. This corresponds to the ealry stage of an ICF
target implosion.. We focus on self-similar ablation flows presenting a large Mach number in
the conduction zone, and possibly containing a Chapman–Jouguet point [5]. Numerical results
are compared to those of the local analysis [3].
References
[1] S. Atzeni and J. Meyer-ter-Vehn, Oxford University Press (2004)
[2] Y. Saillard, P. Arnault, V. Silvert, Phys. Plasma 17, 123302 (2010)
[3] J.M Clarisse, 44th EPS Conf. Plasma Physics (2017)
[4] V. Yu. Bychenkov and W. Rozmus, Phys. Plasma 22, 082705 (2015)
[5] J. M. Clarisse, J. L. Pfister, S. Gauthier, C. Boudesocque-Dubois, J. Fluid Mech. (submitted)
