Jean-Gabriel THIRIET

PhD Student

Resarch activities at CPHT: Theory of Plasmas

Thesis : Stability of ablation flows in inertial confinement fusion: receptivity
Advisors: Arnaud Couairon et Jean-Marie Clarisse (CEA)

Research interests: Hydrodynamics, Inertial confinement fusion, Laser-matter interaction

Abstract:

Inertial confinement fusion (ICF) aims at producing energy from thermonuclear fusion reactions between low atomic-number elements. A possible approach for reaching the high densities and temperatures required for triggering these fusion reactions, consists in imploding a spherical capsule, filled with a mixture of fusible elements, by means of a high energy density irradiation. During this process, various hydrodynamic instabilities occur which may be detrimental to the ignition and burn of the fusible material. The instability of the heat-wave flow – ablation flow – which prevails during the capsule early irradiation is one of those. The major difficulty raised by the analysis of this instability lies in the unsteadiness, compressibility and confinement of the background flow. However such an analysis may be carried out using, as background flows, self-similar solutions of the gas dynamics equations with nonlinear heat conduction (Clarisse et al., J. Fluid Mech. 2008).
The present project aims at determining, for self-similar flows representative of the X-ray irradiation of an ICF capsule, the external perturbations that are the most detrimental to the flow stability – receptivity analysis. This analysis will be conducted using a direct-adjoint method of non-modal stability theory (Schmid, Ann. Rev. Fluid Mech. 2007) that has been developed specifically for such flows. Results will be tested in a more realistic context by means of `multi-physics' simulations of ICF capsule implosions.