Influence of magnetic fields on electron-ion recombination at very low energies

Radiative recombination (inverse photoionization) is believed to be well un derstood since the beginning of quantum mechanics. Still, modern experiment s consistently reveal excess recombination rates at very low electron-ion c enter-of-mass energies. In a detailed study on recombination of F and C ion s with magnetically guided electrons we explored the yet unexplained rate e nhancement, its dependence on the magnetic field B, the electron density n( e), and the beam temperatures T-perpendicular to and T-parallel to. The exc ess scales as T-perpendicular to(-1/2) and, surprisingly, as T-parallel to( -1/2), increases strongly with B, and is insensitive to n(e). This puts str ong constraints on explanations of the enhancement.