Test and analysis of uniform magnetic fields for imaging of electrons produced in ion-atom collisions

In order to expand the solid angle for imaging of electrons in ion-atom collisions, we designed a complex Helmholtz coils composed of four single coils. Theoretical simulations were carried out to optimize the arrangement of the coils. The complex is constructed according to the theoretical analysis, and the magnetic fields were measured for interested regions. The measured results show that the relative uniformity of the magnetic fields is +/- 0.6%, which satisfies the requirements of collision experiments.

High-order harmonic generation and multi-photon ionization of Na-2 in laser fields

In this paper high-order harmonic generation (HHG) spectra and the ionization probabilities of various charge states of small cluster Na-2 in the multiphoton regimes are calculated by using time-dependent local density approximation (TDLDA) for one-colour (1064 nm) and two-colour (1064 nm and 532 nm) ultrashort (25 fs) laser pulses. HHG spectra of Na2 have not the large extent of plateaus due to pronounced collective effects of electron dynamics. In addition, the two-colour laser field can result in the breaking of the symmetry and generation of the even order harmonic such as the second order harmonic. The results of ionization probabilities show that a two-colour laser field can increase the ionization probability of higher charge state.

Angular distribution of characteristic photons after radiative electron capture at strong central fields

We investigate the difference in the angular distribution of Ly-alpha(1) and K alpha(1) photons from hydrogenlike and heliumlike ions of uranium after radiative electron capture to the L shell. The strong anisotropy in the former case is changed to a very small one in the latter case. Our calculations support the observation. The effect takes place even in the limiting case of noninteracting electrons, being caused by the Pauli principle.