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  • 2000-2004  (2)
  • 1995-1999  (1)
  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The 10 GHz ECR-I ion source at ATLAS is being modified to create a small inner volume within the main plasma chamber to reduce the residual helium background gas load. This effort is part of an experiment to measure the residual concentration of 3He in highly isotopically enriched 4He samples. The modification consists of a new extractor electrode on which is integrally mounted a 2.5-cm-diam quartz tube of approximately 8 cm length. Energizing just the extraction coil produces an ECR only inside the quartz volume. The quartz tube is pumped only through the 1-mm-diam extraction hole. rf power is provided by propagation through the main plasma tank acting as a multimode waveguide. The source must operate in the pressure regime of 10–200 mTorr in order to achieve sufficient sensitivity to measure a 3He/4He ratio of approximately 1×10−15. Results of these tests and the operation of the source in this highly unusual mode will be presented. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two techniques for the discrete injection of material into an Electron Cyclotron Resonance ion source (ECRIS) have been developed for the purpose of measuring the ionization and confinement times of ion species. Previously only solid materials in conjunction with a pulsed laser were used in these studies due to the discrete material introduction produced by this configuration. The first method replaces the pulsed laser with a fast high voltage pulse applied to a sputter sample. The high voltage pulse has a rise time of 100 ns, fall time of 80.0 μs, and variable pulse duration. The second method utilizes a fast-pulsed gas valve capable of producing a gas pulse 160 μs in width. These pulse widths are well below the ionization times of the lower charge states and thus allows for time measurements to be made of all charge states. Both of these techniques can be employed to study the effects of rf power, coil configuration, biased disk, and gas mixing on ionization and confinement times. Rise times for neon, argon, and gold will be presented. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 359 (1999), S. 81-91 
    ISSN: 1432-1912
    Keywords: Key words Ryanodine ; CICR ; Calcium-activated ; chloride currents ; Action potential after-depolarizations ; Niflumic acid ; Dantrolene ; Cultured sensory neurones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The whole-cell recording technique was used to investigate the actions of a calcium release channel ligand, ryanodine, on calcium-activated chloride conductances, and to evaluate ryanodine-sensitive Ca2+-induced Ca2+ release from intracellular stores in cultured neonatal rat DRG neurones. The aim of the project was to use ryanodine as a pharmacological tool to evaluate calcium-induced calcium release in the cell bodies of cultured DRG neurones. Action potential after-depolarizations were attenuated by extracellular application of the chloride channel blocker, niflumic acid (10 µM), and by ryanodine (10 µM); these actions occurred without concurrent changes in evoked action potentials. Ryanodine and caffeine (10 mM) activated calcium-dependent conductances and the responses to ryanodine were attenuated by depletion of caffeine-sensitive Ca2+ stores. The current clamp data were complicated by changes in potassium conductances so studies were carried out under voltage clamp and voltage-activated calcium currents and calcium-activated chloride and non-selective cation currents were isolated pharmacologically. Ryanodine (10 µM) evoked delayed, inward, calcium-activated non-selective cation and chloride currents which reversed close to 0 mV and were attenuated by N-methyl-d-glucamine, niflumic acid and dantrolene. Consistent with actions on action potential after-depolarizations, niflumic acid (10 µM) and ryanodine (10 µM) attenuated calcium-activated chloride currents evoked by calcium entry through voltage-activated calcium channels. Niflumic acid and ryanodine had no effects on voltage-activated calcium currents evoked from a holding potential of –90 mV by voltage step commands to 0 mV. In conclusion calcium-activated chloride conductances appear to be activated in part by calcium released from ryanodine-sensitive stores, and significant calcium-induced calcium release may occur locally in cell bodies of DRG neurones as a result of calcium entry through voltage-activated channels during an action potential.
    Type of Medium: Electronic Resource
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