Reduction of fast ion drag in the presence of 'hollow' non-Maxwellian electron distributions

It is argued that the electronic stopping power in a plasma should be expected to exhibitsignificant differences in the presence of effects that shift the electron distribution function away from a Maxwellian. This is potentially important for nuclear reactions produced by laser-drivenion beams, where non-Maxwellian effects may have to be considered. We have calculated the electronic stopping power for a number of model distributions. Importantly, comparisons with the Maxwellian are done under the condition of energy density parity. 'Hollow' electrondistribution functions (e.g.f proportional to v(n)f(max)) could be expected to show a reduced stopping power(when v(i)/v(t)<1). We show that this is indeed the case and that the difference can become a factor of 70. The super-Gaussian electron distribution function, on the other hand, will always show a higher stopping power than the Maxwellian for orders greater than 2.