Indications of Strongly Flux-Limited Electron Thermal Conduction in Laser-Target Experiments

SQM 2006: theory summary and perspectives

“…Such plasmas are characterized by strongly excited random field modes in certain regimes of instability, which coherently scatter the charged particles and thus reduce the rate of momentum transport. The scattering by turbulent fields in electromagnetic plasmas is known to greatly increase the energy loss of charged particles [100] and reduce the heat conductivity [101,102] and the viscosity [103,104] of the plasma. Following Abe and Niu [104], the contribution from turbulent fields to transport coefficients was called "anomalous".…”

Multiple spherically converging shock waves in liquid deuterium

“…For direct-drive ICF target designs, radiationhydrodynamic codes have long used a heuristic flux-limiter model 16 to simulate the reduced flux of energy from the corona, where the laser energy is deposited, to the ablation surface where pressure is applied to the target. To simulate many experimental results, the heat flux in some regions had to be limited to $6% of that predicted by the Spitzer-Härm free-streaming limit.…”

“…It treats the plasma as a two-temperature (ions and electrons), single-velocity fluid. LILAC includes the following physics: flux-limited thermal electron transport, 25,26 inverse-bremsstrahlung absorption, 27 radiation transport with local-thermodynamic-equilibrium (LTE) and non-LTE atomic physics options, 28 thermonuclear reactions 29 and the transport of their primary charged particles, 30 suprathermal electron transport, 31 and a choice of equations of state, including SESAME, 32 analytic ThomasFermi using Bell's formulation, 33 QEOS, 34 and ideal gas.…”

Cryogenic-target performance and implosion physics studies on OMEGA

“…10 The decompression at the ablation front is caused by heating from the high-energy tail of the electron distribution. The decompression at the ablation surface reduces the growth rate of the Rayleigh-Taylor ͑RT͒ instability.…”

“…9 The target acceleration was measured using side-on radiography with a streak camera using ϳ2 keV x rays from a dysprosium sidelighter and compared with two-dimensional ͑2D͒ DRACO simulations. 6 The simulations used a local model for electron transport 10 with a time-dependent flux limiter derived from a one-dimensional ͑1D͒ nonlocal thermal-electron-transport model. 11 The nonlocal model solves the Boltzmann equation with Krook's collision operator and an appropriate electrondeposition length.…”