M. L. A. Raphaelian

The KSU-CRYEBIS: A unique ion source for low-energy highly charged ions

The CRYogenic electron beam ion source at Kansas State University has been in operation since spring 1989. It produces up to Ar18+, Kr34+, and Xe44+ on a regular basis. Acceleration tubes and a beamline system were added during 1990. The ion source is mounted on a high voltage platform, which can be used to vary the ion energies between 2 and 200 kV per charge. The extraction‐, analyzing‐, and beamline systems were designed to accept a wide range of ion masses and charge states with the mass energy product (M⋅E/q2) stretching over four orders of magnitude. The system is used to study the low‐energy highly charged ions interacting with electrons, atoms, thin foils, and surfaces.

Production, operation and status of the KSU CRYEBIS facility

The KSU CRYEBIS is a CRY ogenic Electron Beam Ion Source located on a high voltage platform, dedicated to the exploration of the physics of the highly-charged, low-energy ions. This paper summarizes the research accomplished by our users over the last three years. It discusses the experiences encountered in the operation and production over the last three years. The major improvements accomplished over the last three years and the present capabilities are also described. The paper ends with a discussion of the user facility, the available techniques and equipment.

Angular distributions in charge-transfer collisions of 50 keV Arl5+ with Ar

We report on angular distribution measurements in 50 keV Ar15+ on Ar charge-transfer collisions. Distributions corresponding to the production of up to quintuply-charged recoils were obtained, and compared to the predictions of the molecular classical overbarrier model (MCBM) of Niehaus (1988) under different assumptions. We found no evidence that the contributions of the tightly bound target electrons are overestimated by the MCBM, in contrast with the observations of Danared et al. (1987) and Guillemot et al. (1990). The e-values of Ali et al. (1993) for the same processes were compared to the model predictions under similar assumptions and the trends were consistent with those of the angular distributions.

On the radiative stabilization in slow double-electron capture collisions of highly charged ions with neutral atoms

The authors have measured the radiative stabilization probability in double-electron capture collisions for the systems 10 keV u-1 Krq+ (q=13-34) and Arq+ (q=6-17) on Ar, and examined its velocity dependence for Ar8+ on Ar. The measured probability exhibits pronounced structures as a function of q. A model incorporating the initial population, the collision velocity, and the core structure of the incoming projectile is proposed, and the gross features are fairly accounted for. The results support the importance of populating asymmetric Rydberg states and reveal the crucial role played by the projectile core structure. The velocity dependence measurements favour a post-collision interaction mechanism for the population of the asymmetric Rydberg states, such as that proposed by Bachau et al. (1992).