Fast lithium-beam spectroscopy of tokamak edge plasmas

Review of Scientific Instruments (Impact Factor: 1.6). 08/1993; DOI: 10.1063/1.1144460
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    ABSTRACT: The lithium beam diagnostic at ASDEX Upgrade routinely delivers electron density profiles in the plasma edge by lithium beam impact excitation spectroscopy. An accurate background subtraction requires a periodically chopped lithium beam. A new, improved chopping system was developed and installed. It involves a voltage modulation for the extractor electrode and the beam deflection plates. The modulation of the extractor electrode reduces the unused portion of lithium ions and improves the stability of the beam with respect to its position. Furthermore, the data indicate an extended emitter lifetime. The extractor chopping was also found to be insensitive to sparks. The deflection chopping experiments demonstrated beam chopping in the kilohertz range. The significantly higher modulation frequency of the deflection chopping improves background subtraction of fast transient events. It allows a more accurate density measurements in the scrape off layer during impurity injections and edge localized modes.
    The Review of scientific instruments 02/2012; 83(2):023501. · 1.52 Impact Factor
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    ABSTRACT: Recoil ion momentum spectroscopy has been applied to study low energy, state-selective single electron capture by highly charged projectiles. The specific systems investigated are fully stripped 6.82 keV/u Ne{sup 10+} and 6.75 keV/u Ar{sup 18+} on He. Measurements of the He{sup +} recoil ion longitudinal momenta are used to determine the final {ital n}-state dependence of the captured electron. Simultaneous measurement of the transverse momenta of the recoil ion yields information about the impact parameter dependence of the reaction and the reaction window for electron capture. {copyright} {ital 1996 The American Physical Society.}
    Physical Review Letters 06/1996; 76(20):3679-3682. · 7.73 Impact Factor
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    ABSTRACT: We present an experimental and theoretical study on the modelling of fast (5 keV amu −1) Li beams which are used for diagnostics of fusion edge plasmas. The atomic collision database utilized for modelling the Li beam attenuation has been revised and extended by detailed investigations of Li(nl; n 3) populations resulting from ion impact excitation. We obtain good agreement between measured and calculated Li(nl) populations for an Li beam passing the edge plasma region of the ASDEX Upgrade tokamak and WENDELSTEIN 7 AS stellarator, respectively, at IPP Garching.
    Plasma Physics and Controlled Fusion 01/1999; 41:471-484. · 2.37 Impact Factor


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