Continuum emission due to bremsstrahlung and direct radiative recombination is studied in two types of fusion-plasmas with non-Maxwellian electron distributions. The calculated emissivity coefficients Jω(hω) are shown to depart from the Maxwellian ones. The main consequence of the modification of the spectrum is to invalidate the usual electron temperature diagnostic which consits in equating dlnjω(hω)/d(hω) to l/kTe.

Case I corresponds to the critical density region of a laser-produced plasma ( Langdon 1980, Mora and Yahi 1982 ). The distribution function is cm exp (-v/vo,m)m with m=5 for all values of the incident electron velocity v. Case II corresponds to very steep temperature gradients for which the spacial scale of the transport region is larger than the gradient scale itself (Albritton 1983, Luciani et al. 1984, Campbell 1984). On the higher temperature side of the heat front, the tail of the distribution is depleted with respect to the Maxwellian one. At a particular distance from it, this tail can be roughly described by the above analytical function but with m=3.