Effects of polarization on laser-induced electron-ion recombination

Abstract

The polarization dependence of laser-induced radiative recombination (LIR) to ${\mathrm{D}}^{+}$ ions was investigated in the electron cooler of the CRYRING storage ring. The LIR gain as a function of wavelength into $n$ $=$ 3 principal quantum states of deuterium was measured at laser beam polarization angles of 0\ifmmode^\circ\else\textdegree\fi{} and 90\ifmmode^\circ\else\textdegree\fi{} with respect to the direction of the motional electric field in the interaction region. For the case of the polarization vector parallel to the external field, there is a double-peak structure in the gain curve that indicates a polarization effect in the LIR process. The two polarization directions also reveal a different width for the respective gain curves, giving additional evidence for the polarization effect, clearly seen by the behavior of a defined polarization parameter. The obtained polarization effect indicates a high sensitivity in recombination processes to external fields.