Effects of Nonequilibrium Free Electrons on Atomic Processes

Radiative and collisional atomic processes are proven to be affected critically by the shape of the free electron distribution. For a bi-Maxwellian distribution with temperatures T_x and T_⊥ for the motions in the x and the perpendicular directions, the radiative recombination rate is enhanced by a factor of ten for T_⊥/T_x=0.1 and becomes infinite in the limit of T_⊥/T_x=0. This enhancement can largely increase the gain in recombination X-ray lasers. With the aid of applied magnetic fields, this temperature anisotropy can easily be created. Possible applications to laser-produced plasmas and magnetically confined plasmas such as in tandem mirror devices are discussed.