Evidence for a hot electron flux limit in laser-produced plasma experiments

The necessity to impose a flux limit on the thermal electron transport in diffusion calculations of laser produced plasmas to explain the observed partition of energy into fast and slow ions and X-rays is outlined. The effect of such a limit is to retain the deposited energy in the corona of the target. The containment increases the energy loss to fast ions, reduces the X-ray emission, and reduces the hydrodynamic efficiency. Although calculations for plasmas produced by lasers having wavelengths of 1 (SIGMA)m or shorter agree with experiment when a flux limit which is 1/30 times the classical flux limit is applied to the electron thermal flux. It is shown that such a flux limit cannot explain the results obtained for 10 (SIGMA)m lasers. It is shown that it is necessary to invoke a flux limit on the hot or suprathermal electrons.