Thermal heat-flux reduction in laser-produced plasmas

It is shown that the non-Maxwellian heating by inverse bremsstrahlung which results in a truncation of the tail of the electron-distribution function is responsible for a reduction of the thermal conductivity in a smooth temperature gradient by a factor of 3 to 4 from the Spitzer-H\"arm conductivity. In a steep temperature gradient, the reduction is still a factor of about 1.5 from the recent nonlinear theories based on a Maxwellian electron-distribution source.