[en] The availability of intense, high charge state ion beams from ECR ion sources has had significant impact not only on the upgrading of cyclotron and synchrotron facilities, but also on multicharged ion collision research, as evidenced by the increasing number of ECR source facilities used at least on a part time basis for atomic physics research. In this paper one such facility, located at the ORNL ECR source, and dedicated full time to the study of multicharged ion collisions, is described. Examples of applications of ECR ion source beams are given, based on multicharged ion collision physics studies performed at Oak Ridge over the last few years. 21 refs., 18 figs., 2 tabs

[en] During the past year, the ORNL ECR source has fully demonstrated its capability for providing the high charge state, high current beams required for our group's atomic physics research program. The ECR source, which is dedicated completely for use in our investigations of the collisional properties of multicharged ions, has permitted considerable expansion of research in some areas, and has opened other areas that were experimentally unaccessible to us previously. A partial list of publications resulting from implementation of the ECR source is provided in the appendix

[en] In this article we extend our earlier studies of the azimuthal dependences of low energy projectiles scattered in large angle quasi-binary collisions from Au(110). Measurements are presented for 20 keV Ar⁹⁺ at normal incidence, which are compared with our earlier measurements for this ion at 5 keV and 10⁰ incidence angle. A deconvolution procedure based on MARLOWE simulation results carried out at both energies provides information about the energy dependence of projectile neutralization during interactions just with the atoms along the top ridge of the reconstructed Au(110) surface corrugation, in comparison to, e.g., interactions with atoms lying on the sidewalls. To test the sensitivity of the agreement between the MARLOWE results and the experimental measurements, we show simulation results obtained for a non-reconstructed Au(110) surface with 20 keV Ar projectiles, and for different scattering potentials that are intended to simulate the effects on scattering trajectory of a projectile inner shell vacancy surviving the binary collision, In addition, simulation results are shown for a number of different total scattering angles, to illustrate their utility in finding optimum values for this parameter prior to the actual measurements

[en] A multicharged ion source based on Electron Cyclotron Resonance (ECR) heating has been designed and built at ORNL. The ECR ion source, which is completely dedicated for atomic physics collision studies, produces higher charge states and higher beam intensities than the present ORNL PIG multicharged ion source, and will thus permit study of collision processes involving ions of higher charge states in experiments requiring higher beam intensities than could be previously obtained in our laboratory. The source has already produced up to fully stripped C and O beams, as well as up to He-like Ar beams. Measurements of the energy spread of ions extracted from the ion source operating in both single-stage and two-stage mode are described. In addition, initial results of total cross section measurements for fully stripped light ions incident on atomic hydrogen in the energy range 0.2 to 10 keV are presented. 13 references, 7 figures, 1 table

[en] The equilibrium factor F-₁/sup infinity/ for H⁺ (or D⁺) incident on a thick Cs vapor target is an important parameter in the design of charge transfer cells for use in MFE neutral-beam injection schemes. To determine whether excitation of the Cs (6p) state by H⁺ significantly affects the thick-target H^- yield, F-₁/sup infinity/ was measured for both H^- and H⁺ incident on Cs in the energy range 150 to 1000 eV. The yields F-₁/sup infinity/ were found to be the same for H⁺ and H^- incident on Cs; evidently Cs (6p) excitation by H⁺ plays a negligible role in H^- formation in a thick target. Measurements of F-₁/sup infinity/ with D^- incident showed no observable isotope effect. 1 figure

[en] Some recent experimental results in the area of multicharged ion-surface interactions are summarized. Discussed are measurements of projectile K-Auger electron emission during interactions of hydrogen-like multicharged ions with clean and cesiated metal surfaces, measurements of total electron yields for various multicharged ions incident on metal targets, and measurements of projectile angular scattering during grazing metal surface collisions. The various experimental results are presented to illustrate progress in the understanding of multicharged ion-surface interactions in the area of above- vs sub-surface neutralization and relaxation processes, as well as to identify certain aspects of such interactions where the picture is as yet still incomplete

[en] A crossed-beams experiment designed to measure total electron-loss cross sections by H⁰ in collision with various multiply charged plasma impurity ions utilizes a fast H⁰ beam obtained by passing energy-analyzed protons through a neutralizer cell. Since such a neutral beam is known to contain a small but finite amount of excited atoms in various n states with relative population P/sub n/ and since the cross sections sigma/sub n/ increase rapidly with n, the values of P/sub n/ are needed to deduce sigma/sub n/ from the measured apparent cross section sigma/sub A/, which is a sum of products P/sub n/sigma/sub n/ of all contributing states. The measured sigma/sub A/ for 40-keV H⁰ on N³⁺ ions is presented as a function of a transverse electric field applied to the H⁰ beam prior to the interaction regions. The apparent cross section decreases with increasing field. The populations P/sub n/ were determined from auxiliary experiments in which the intensity of the H⁰ beam transmitted through the ionizing field was measured for a range of field strengths E. The measured transmissions are plotted vs E/sup 1/2/ for a 40-keV H⁰ beam. 2 figures

[en] Using high resolution magnetic analysis, we have measured energy spreads of Ar/sup +q/ (1 < q < 12) ion beams extracted from the ORNL ECR ion source under a number of different ECR plasma conditions. The measured energy spreads for the different charge states fall in the range 8 to 20 eV per charge and are all roughly proportional to the ion charge. In addition, we have used a combination of magnetic and electrostatic analysis to investigate the high charge state tail of the extracted Ar/sup +q/ charge state distribution. Charge states up to +16 have been positively identified; in addition, tentative identification of extracted Ar⁺¹⁷ ions has been made, with total intensity in the range 10 to 20 kHz. 6 refs., 7 figs

[en] The ORNL ECR multicharged ion source, dedicated for studying the atomic physics interactions of multicharged ions with atoms, ions, electrons, and surfaces has been in operation since 1984. High charge state ion beams ranging from fully stripped light ions (up to Ne) to up to 40% stripped heavy ions (A ∼ 200) have bee produced. Ion beams of the metallic elements developed to date include Cr, Fe, Ni, Ta, and Au, and are obtained by the use of a solid feed technique

[en] This paper will be an overview presenting some of the basic atomic collisions processes (gas phase) which are fundamental to production and destruction of H^-(D^-). More detailed discussions of the most important processes will be left to other papers at this Symposium, and primarily new results since the 1977 Symposium will be discussed. Recent results provide insight into mechanisms responsible for the high H^-(D^-) ion fractions in hydrogen gas discharges, and the ion-atom collision processes important for double capture negative ion sources are better understood than in 1977