VSC Project 70136 Report on Research Performed in 2010

Collisions between neutral hydrogen isotopes and multiply charged ions resulting in charge exchange (CX) and ionization (ION) have been the subject of a large number of studies in the past [1]. Major motivation arises from thermonuclear fusion research since these kinds of cross sections are needed for a variety of applications, in particular Charge Exchange Recombination Spectroscopy (CXRS) [2]. This diagnostic technique relies on the injection of fast neutral hydrogen (deuterium) atoms into the hot region of the plasma (e.g., by using the neutral heating beam). Through collisions with multiply charged impurity ions, the electron from the hydrogen can be captured into excited Rydberg states of the ion. The subsequent emission of photons with characteristic wavelengths and intensities, and Doppler broadening and shifts allows determination of the density and temperature of the plasma ions as well as the direction and the velocity of the plasma flow [2]. The diagnostics of hot fusion plasmas in general is an elaborate field of research. The precise determination of plasma parameters such as the ion temperature, the direction of the plasma flow, or the plasma density relies on state-of-the-art experimental techniques as well as sophisticated computational algorithms that analyze and evaluate the measured data. The latter strongly depend on the accuracy of the fundamental atomic data. Although undeniably important, the role of CX in the diagnostics of hot fusion plasmas is not the only field of application. When highly charged ions from the solar wind interact with neutral gases in cometary atmospheres an electron can transfer from the gas atom or molecule to an excited state of the ion, eventually resulting in the emission of soft x-ray radiation. The detected spectra are rather complex and their analysis requires a substantial amount of effort. Also here, the quality of the results strongly depends on the quality of the underlying data. The calculations were performed using the well-known Atomic-Orbital Close-Coupling (AOCC) method [1, 3]. Fig.1 shows the collision frame and geometry in the impact parameter approximation: the (x,z) collision plane is defined by the projectile (P) velocity ~v and the target (T). ~b is the impact parameter, ~ R the internuclear separation vector, and ~ rt and ~ rp the position vectors of the active electron the coordinate system of the target respectively the projectile. AOCC is a semi-classical theory where the collision centers (target and projectile) travel on straight, classical trajectories and the active electron is treated quantum mechanically. The time-dependent Schrödinger equation (TDSE) is solved using the following Hamiltonian and the following expansion of the wavefunction into basis functions: