Highly Charged Ion Collision Processes in High Temperature Fusion Plasmas

Tawara, H.

doi:10.1007/978-94-017-0542-4_4

Cited by 3 publications

(2 citation statements)

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“…Subsequent to the interaction the excited HCI stabilizes via a combination of radiative decay and autoionization. Studies of charge exchange are important for a fundamental understanding of atomic processes and for applications such as spectral diagnostics of fusion plasmas heated by neutral beam injection [2] and the determination of ion storage times in ion traps and storage rings [3]. Further impetus to this area of research stems from the discovery of x-ray emission from comets by Lisse et al in 1996 [4], for which charge exchange between HCIs in the solar wind and neutrals in the coma of the comet has been established as the main emission mechanism [5].…”

Section: Introductionmentioning

confidence: 99%

Energy dependence of angular momentum capture states in charge exchange collisions between slow highly charged argon ions and argon neutrals

et al. 2008

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K-shell x-ray emission measurements of electron capture into Rydberg states of Ar 17+ and Ar 18+ions are carried out as a function of collision energy in order to investigate the energy dependence of angular momentum capture states in slow charge exchange collisions. The highly charged ions are produced using an Electron Beam Ion Trap and extracted onto an external argon gas target. A retardation assembly in the beamline allows projectile energies from ∼2 keV/amu down to ∼5 eV/amu to be selected. For decreasing collision energies a shift to electron capture into low orbital angular momentum capture states is observed. Comparative K-shell x-ray emission measurements of electron capture by Ar 17+ and Ar 18+ ions from background gas in the trap are also presented. The results of the trapping experiments are in discrepancy with those obtained using extracted ions and possible explanations are discussed.

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Section: Introductionmentioning

confidence: 99%

Energy dependence of angular momentum capture states in charge exchange collisions between slow highly charged argon ions and argon neutrals

et al. 2008

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“…Charge exchange as a result of low energy collisions between highly charged ions and gases has become an area of increased interest due to applications in high temperature fusion plasma diagnostics [1] and the observation of x-ray emission from comets [2]. In the first case, heavy ions present as impurities in the plasma capture electrons from inherent or injected neutrals and in the second, heavy ions in the solar wind capture electrons from neutrals in the comet's bow shock region.…”

Section: Introductionmentioning

confidence: 99%

Charge exchange of highly charged argon ions as a function of projectile energy

Allen

Biedermann

Radtke

et al. 2007

J. Phys.: Conf. Ser.

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X-ray emission of highly charged argon ions following charge exchange collisions with argon atoms has been measured as a function of projectile energy. The ions are extracted from the Electron Beam Ion Trap (EBIT) in Berlin and selected according to their massto-charge ratios. Experiments focussed on hydrogen-like and bare argon ions which were decelerated from 125q eV/amu to below 0.25q eV/amu prior to interaction with an argon gas target. The x-ray spectra recorded probe the cascading transitions resulting from electron capture into Rydberg states and are found to vary significantly with collision velocity. This indicates a shift in the orbital angular momentum of the capture state. Hardness ratios are observed to increase with decreasing projectile energy though at a rate which differs from the results of simulations. For comparison, measurements of the x-ray emission following charge exchange within the trap were carried out and are in agreement with the findings of the EBIT group at LLNL. Both of these in situ measurements, however, are in discrepancy with the results of the experiments using extracted ions.

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