Electron impact double ionization of helium from classical trajectory calculations

With a recently proposed quasiclassical ansatz (Geyer and Rost 2002 J. Phys. B: At. Mol. Opt. Phys. 35 1479) it is possible to perform classical trajectory ionization calculations on many electron targets. The autoionization of the target is prevented by a Moeller-type backward-forward propagation scheme and allows us to consider all interactions between all particles without additional stabilization. The application of the quasiclassical ansatz for helium targets is explained and total and partially differential cross sections for electron impact double ionization are calculated. In the high-energy regime, the classical description fails to describe the dominant sequential double-ionization process, which leads to big deviations from experiment, whereas for low energies the total cross section is reproduced well. Differential cross sections calculated at 250 eV await their experimental confirmation