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K Tsumori - One of the best experts on this subject based on the ideXlab platform.
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cavity ring down spectroscopy system for the evaluatIon of negative hydrogen Ion Density at the elise test facility
Review of Scientific Instruments, 2020Co-Authors: A Mimo, U. Fantz, H Nakano, C Wimmer, D Wunderlich, K TsumoriAbstract:The large RF negative hydrogen (deuterium) Ion source at the ELISE test facility (half of the ITER-NBI source size) has been equipped with a Cavity Ring-Down Spectroscopy (CRDS) system, in order to measure the negative hydrogen (deuterium) Ion Density in the regIon in front of the plasma grid (first grid of the extractIon system). The challenge of this diagnostic for ELISE relies on the large size of the source and therefore on the plasma length across which the measurements are performed as well as the long pulses at RF power, which can affect the cavity mirror reliability. A dedicated experiment on the mirror reliability was performed, ensuring the feasibility of measurements for long pulses (several hundred seconds) at high RF power. Two horizontal lines of sight were dedicated to CRDS: the measured Density was in the range between 4 × 1016 and 1 × 1017 m-3, with a slightly higher Density for the bottom lines of sight, for both the isotope hydrogen and deuterium. Different temporal evolutIon was observed for the two isotopes, showing a higher instability for the deuterium case: this is in correlatIon with the extracted negative Ion current Density and inversely correlated with the coextracted electron current Density. The CRDS system allowed performing the first measurements of negative Ion Density for a long pulse (1000 s) in a large source: the temporal behavior and the effect of the beam extractIon will also be discussed.
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cavity ring down spectroscopy system for the evaluatIon of negative hydrogen Ion Density at the elise test facility
Review of Scientific Instruments, 2020Co-Authors: A Mimo, U. Fantz, H Nakano, C Wimmer, D Wunderlich, K TsumoriAbstract:The large RF negative hydrogen (deuterium) Ion source at the ELISE test facility (half of the ITER-NBI source size) has been equipped with a Cavity Ring-Down Spectroscopy (CRDS) system, in order to measure the negative hydrogen (deuterium) Ion Density in the regIon in front of the plasma grid (first grid of the extractIon system). The challenge of this diagnostic for ELISE relies on the large size of the source and therefore on the plasma length across which the measurements are performed as well as the long pulses at RF power, which can affect the cavity mirror reliability. A dedicated experiment on the mirror reliability was performed, ensuring the feasibility of measurements for long pulses (several hundred seconds) at high RF power. Two horizontal lines of sight were dedicated to CRDS: the measured Density was in the range between 4 × 1016 and 1 × 1017 m−3, with a slightly higher Density for the bottom lines of sight, for both the isotope hydrogen and deuterium. Different temporal evolutIon was observed for the two isotopes, showing a higher instability for the deuterium case: this is in correlatIon with the extracted negative Ion current Density and inversely correlated with the coextracted electron current Density. The CRDS system allowed performing the first measurements of negative Ion Density for a long pulse (1000 s) in a large source: the temporal behavior and the effect of the beam extractIon will also be discussed.The large RF negative hydrogen (deuterium) Ion source at the ELISE test facility (half of the ITER-NBI source size) has been equipped with a Cavity Ring-Down Spectroscopy (CRDS) system, in order to measure the negative hydrogen (deuterium) Ion Density in the regIon in front of the plasma grid (first grid of the extractIon system). The challenge of this diagnostic for ELISE relies on the large size of the source and therefore on the plasma length across which the measurements are performed as well as the long pulses at RF power, which can affect the cavity mirror reliability. A dedicated experiment on the mirror reliability was performed, ensuring the feasibility of measurements for long pulses (several hundred seconds) at high RF power. Two horizontal lines of sight were dedicated to CRDS: the measured Density was in the range between 4 × 1016 and 1 × 1017 m−3, with a slightly higher Density for the bottom lines of sight, for both the isotope hydrogen and deuterium. Different temporal evolutIon was observ...
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exploring deuterium beam operatIon and the behavior of the co extracted electron current in a negative Ion based neutral beam injector
Nuclear Fusion, 2019Co-Authors: K Ikeda, K Tsumori, H Nakano, M Kisaki, Kenichi Nagaoka, S Kamio, Y Fujiwara, Y Haba, M OsakabeAbstract:The achievements of the deuterium beam operatIon of a negative-Ion-based neutral beam injector (N-NBI) in the large helical device (LHD) are reported. In beam operatIon in LHD-NBIs, both hydrogen (H) and deuterium (D) neutral beams were generated by changing the operatIon gas using the same accelerator. The maximum accelerated deuterium negative-Ion current () reaches 46.2 A from two beam sources with the averaged current Density being 190 A m−2 for 2 s, and the extracted electron to accelerated Ion current ratio () increases to 0.39 using 5.6 V high bias voltage in the first deuterium operatIon in 2017. An increase of electron Density in the vicinity of the plasma grid (PG) surface, which is considered the main reason for the increase of co-extracted electrons in a beam, is confirmed by the half-size research negative-Ion source in the neutral beam test stand at the NatIonal Institute for FusIon Science (NIFS). The deuterium negative-Ion Density is also larger than the hydrogen negative-Ion Density in the vicinity of the PG surface using the same discharge conditIons. In the latest experimental campaign in 2018, increases to 55.4 A with the averaged current Density being 233 A m−2 for 1.5 s using the shot extractIon gap length. The low of 0.31 can be maintained by using high discharge power. The various parameters mentIoned above are defined in detail below.
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high Ion temperature experiments with negative Ion based neutral beam injectIon heating in large helical device
Nuclear Fusion, 2005Co-Authors: Y Takeiri, S Morita, K Tsumori, K Ikeda, M Osakabe, K Nagaoka, M Goto, J Miyazawa, S Masuzaki, N AshikawaAbstract:High-Z plasmas have been produced with Ar and/or Ne gas fuelling to increase the Ion temperature in Large Helical Device (LHD) plasmas heated with high-energy negative-Ion-based neutral beam injectIon (NBI). Although the electron heating is dominant in the high-energy NBI heating, the direct Ion heating power is significantly enhanced in low-Density plasmas due to both an increase in the beam absorptIon (IonizatIon) power and a reductIon of the Ion Density in the high-Z plasmas. Intensive neon- and/or argon-glow discharge cleaning works well to suppress dilutIon of the high-Z plasmas with wall-absorbed hydrogen. As a result, the Ion temperature increases with an increase in the Ion heating power normalized by the Ion Density and reaches 10 keV. An increase in the Ion temperature is also observed with the additIon of centrally focused electron cyclotron resonance heating to a low-Density and high-Z NBI plasma, suggesting improvement of the Ion transport. The results obtained in the high-Z plasma experiments with high-energy NBI heating suggest that an increase in the direct Ion heating power and improvement of the Ion transport are essential to Ion temperature rise, and that a high-Ion temperature could be obtained as well in hydrogen plasmas with low-energy positive-NBI heating which is planned in the near future in the LHD.
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isotope effect of h d volume productIon in low pressure h2 d2 plasmas measurement of vuv emissIons and negative Ion densities
Contributions To Plasma Physics, 2004Co-Authors: Osamu Fukumasa, K Tsumori, Y Tauchi, Shigefumi Mori, N Nakada, Makoto Hamabe, Y TakeiriAbstract:Isotope effect on H–/D– volume productIon is studied by measuring both VUV emissIon and negative Ion Density in the source. In a double plasma type source, under some discharge conditIons, extracted D– currents are nearly the same as H– currents, although VUV emissIon intensity (corresponding to productIon of vibratIonally excited molecules) in D2 plasmas is slightly lower than that in H2 plasmas. Considering the factor √2 due to mass difference, D– Ion Density in the extractIon regIon of the source is higher than H– Ion Density. In another experiment with a rectangular arc chamber, axial distributIons of H–/D– Ion densities in the source are measured directly using a laser photodetachment method. RelatIonship between H–/D– productIon and plasma parameter control with using a magnetic filter (MF) is discussed. Furthermore, relative intensities of extracted negative Ion currents are discussed compared with the negative Ion densities in the source. ProductIon and control of D2 plasmas are well realized with the MF including good combinatIon between the filament positIon and field intensity of the MF. Extracted H– and D– currents depend directly on negative Ion densities in the source. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Y Takeiri - One of the best experts on this subject based on the ideXlab platform.
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high Ion temperature experiments with negative Ion based neutral beam injectIon heating in large helical device
Nuclear Fusion, 2005Co-Authors: Y Takeiri, S Morita, K Tsumori, K Ikeda, M Osakabe, K Nagaoka, M Goto, J Miyazawa, S Masuzaki, N AshikawaAbstract:High-Z plasmas have been produced with Ar and/or Ne gas fuelling to increase the Ion temperature in Large Helical Device (LHD) plasmas heated with high-energy negative-Ion-based neutral beam injectIon (NBI). Although the electron heating is dominant in the high-energy NBI heating, the direct Ion heating power is significantly enhanced in low-Density plasmas due to both an increase in the beam absorptIon (IonizatIon) power and a reductIon of the Ion Density in the high-Z plasmas. Intensive neon- and/or argon-glow discharge cleaning works well to suppress dilutIon of the high-Z plasmas with wall-absorbed hydrogen. As a result, the Ion temperature increases with an increase in the Ion heating power normalized by the Ion Density and reaches 10 keV. An increase in the Ion temperature is also observed with the additIon of centrally focused electron cyclotron resonance heating to a low-Density and high-Z NBI plasma, suggesting improvement of the Ion transport. The results obtained in the high-Z plasma experiments with high-energy NBI heating suggest that an increase in the direct Ion heating power and improvement of the Ion transport are essential to Ion temperature rise, and that a high-Ion temperature could be obtained as well in hydrogen plasmas with low-energy positive-NBI heating which is planned in the near future in the LHD.
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isotope effect of h d volume productIon in low pressure h2 d2 plasmas measurement of vuv emissIons and negative Ion densities
Contributions To Plasma Physics, 2004Co-Authors: Osamu Fukumasa, K Tsumori, Y Tauchi, Shigefumi Mori, N Nakada, Makoto Hamabe, Y TakeiriAbstract:Isotope effect on H–/D– volume productIon is studied by measuring both VUV emissIon and negative Ion Density in the source. In a double plasma type source, under some discharge conditIons, extracted D– currents are nearly the same as H– currents, although VUV emissIon intensity (corresponding to productIon of vibratIonally excited molecules) in D2 plasmas is slightly lower than that in H2 plasmas. Considering the factor √2 due to mass difference, D– Ion Density in the extractIon regIon of the source is higher than H– Ion Density. In another experiment with a rectangular arc chamber, axial distributIons of H–/D– Ion densities in the source are measured directly using a laser photodetachment method. RelatIonship between H–/D– productIon and plasma parameter control with using a magnetic filter (MF) is discussed. Furthermore, relative intensities of extracted negative Ion currents are discussed compared with the negative Ion densities in the source. ProductIon and control of D2 plasmas are well realized with the MF including good combinatIon between the filament positIon and field intensity of the MF. Extracted H– and D– currents depend directly on negative Ion densities in the source. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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study of isotope effect on h d volume productIon in low pressure h2 d2 plasmas using vuv emissIon
PRODUCTION AND NEUTRALIZATION OF NEGATIVE IONS AND BEAMS: Ninth International Symposium on the Production and Neutralization of Negative Ions and Beam, 2002Co-Authors: Osamu Fukumasa, Y Tauchi, Y Yabuki, Shigefumi Mori, Y TakeiriAbstract:Isotope effect on H−/D− volume productIon is studied by using VUV emissIon. Under the same discharge conditIons, VUV emissIon (corresponding to productIon of vibratIonally excited molecules) in hydrogen plasmas is higher than that in deuterium plasma. Within the present experimental conditIons, H− current is higher than D− current, although, considering the factor √2, D− Ion Density in the source is nearly equal to H− Ion Density under low discharge power. Effect of argon additive in negative Ion sources is also discussed briefly.
Anna Freni Sterrantino - One of the best experts on this subject based on the ideXlab platform.
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electric field and air Ion exposures near high voltage overhead power lines and adult cancers a case control study across england and wales
International Journal of Epidemiology, 2020Co-Authors: Mireille B Toledano, Gavin Shaddick, Kees De Hoogh, Daniela Fecht, Anna Freni SterrantinoAbstract:BACKGROUND Various mechanisms have been postulated to explain how electric fields emitted by high voltage overhead power lines, and the charged Ions they produce, might be associated with possible adult cancer risk, but this has not previously been systematically explored in large scale epidemiological research. METHODS We investigated risks of adult cancers in relatIon to modelled air Ion Density (per cm3) within 600 m (focusing analysis on mouth, lung, respiratory), and calculated electric field within 25 m (focusing analysis on non-melanoma skin), of high voltage overhead power lines in England and Wales, 1974-2008. RESULTS With adjustment for age, sex, deprivatIon and rurality, odds ratios (OR) in the highest fifth of net air Ion Density (0.504-1) compared with the lowest (0-0.1879) ranged from 0.94 [95% confidence interval (CI) 0.82-1.08] for mouth cancers to 1.03 (95% CI 0.97-1.09) for respiratory system cancers, with no trends in risk. The pattern of cancer risk was similar using corona Ion estimates from an alternative model proposed by others. For keratinocyte carcinoma, adjusted OR in the highest (1.06-4.11 kV/m) compared with the lowest (<0.70 kV/m) thirds of electric field strength was 1.23 (95% CI 0.65-2.34), with no trend in risk. CONCLUSIonS Our results do not provide evidence to support hypotheses that air Ion Density or electric fields in the vicinity of power lines are associated with cancer risk in adults.
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Electric field and air Ion exposures near high voltage overhead power lines and adult cancers: a case control study across England and Wales.
2020Co-Authors: Mireille B Toledano, Gavin Shaddick, Kees De Hoogh, Daniela Fecht, Anna Freni Sterrantino, James Matthews, Matthew Wright, John Gulliver, Paul ElliottAbstract:BACKGROUND:Various mechanisms have been postulated to explain how electric fields emitted by high voltage overhead power lines, and the charged Ions they produce, might be associated with possible adult cancer risk, but this has not previously been systematically explored in large scale epidemiological research. METHODS:We investigated risks of adult cancers in relatIon to modelled air Ion Density (per cm3) within 600 m (focusing analysis on mouth, lung, respiratory), and calculated electric field within 25 m (focusing analysis on non-melanoma skin), of high voltage overhead power lines in England and Wales, 1974-2008. RESULTS:With adjustment for age, sex, deprivatIon and rurality, odds ratios (OR) in the highest fifth of net air Ion Density (0.504-1) compared with the lowest (0-0.1879) ranged from 0.94 [95% confidence interval (CI) 0.82-1.08] for mouth cancers to 1.03 (95% CI 0.97-1.09) for respiratory system cancers, with no trends in risk. The pattern of cancer risk was similar using corona Ion estimates from an alternative model proposed by others. For keratinocyte carcinoma, adjusted OR in the highest (1.06-4.11 kV/m) compared with the lowest (
M Osakabe - One of the best experts on this subject based on the ideXlab platform.
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exploring deuterium beam operatIon and the behavior of the co extracted electron current in a negative Ion based neutral beam injector
Nuclear Fusion, 2019Co-Authors: K Ikeda, K Tsumori, H Nakano, M Kisaki, Kenichi Nagaoka, S Kamio, Y Fujiwara, Y Haba, M OsakabeAbstract:The achievements of the deuterium beam operatIon of a negative-Ion-based neutral beam injector (N-NBI) in the large helical device (LHD) are reported. In beam operatIon in LHD-NBIs, both hydrogen (H) and deuterium (D) neutral beams were generated by changing the operatIon gas using the same accelerator. The maximum accelerated deuterium negative-Ion current () reaches 46.2 A from two beam sources with the averaged current Density being 190 A m−2 for 2 s, and the extracted electron to accelerated Ion current ratio () increases to 0.39 using 5.6 V high bias voltage in the first deuterium operatIon in 2017. An increase of electron Density in the vicinity of the plasma grid (PG) surface, which is considered the main reason for the increase of co-extracted electrons in a beam, is confirmed by the half-size research negative-Ion source in the neutral beam test stand at the NatIonal Institute for FusIon Science (NIFS). The deuterium negative-Ion Density is also larger than the hydrogen negative-Ion Density in the vicinity of the PG surface using the same discharge conditIons. In the latest experimental campaign in 2018, increases to 55.4 A with the averaged current Density being 233 A m−2 for 1.5 s using the shot extractIon gap length. The low of 0.31 can be maintained by using high discharge power. The various parameters mentIoned above are defined in detail below.
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high Ion temperature experiments with negative Ion based neutral beam injectIon heating in large helical device
Nuclear Fusion, 2005Co-Authors: Y Takeiri, S Morita, K Tsumori, K Ikeda, M Osakabe, K Nagaoka, M Goto, J Miyazawa, S Masuzaki, N AshikawaAbstract:High-Z plasmas have been produced with Ar and/or Ne gas fuelling to increase the Ion temperature in Large Helical Device (LHD) plasmas heated with high-energy negative-Ion-based neutral beam injectIon (NBI). Although the electron heating is dominant in the high-energy NBI heating, the direct Ion heating power is significantly enhanced in low-Density plasmas due to both an increase in the beam absorptIon (IonizatIon) power and a reductIon of the Ion Density in the high-Z plasmas. Intensive neon- and/or argon-glow discharge cleaning works well to suppress dilutIon of the high-Z plasmas with wall-absorbed hydrogen. As a result, the Ion temperature increases with an increase in the Ion heating power normalized by the Ion Density and reaches 10 keV. An increase in the Ion temperature is also observed with the additIon of centrally focused electron cyclotron resonance heating to a low-Density and high-Z NBI plasma, suggesting improvement of the Ion transport. The results obtained in the high-Z plasma experiments with high-energy NBI heating suggest that an increase in the direct Ion heating power and improvement of the Ion transport are essential to Ion temperature rise, and that a high-Ion temperature could be obtained as well in hydrogen plasmas with low-energy positive-NBI heating which is planned in the near future in the LHD.
K Ikeda - One of the best experts on this subject based on the ideXlab platform.
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exploring deuterium beam operatIon and the behavior of the co extracted electron current in a negative Ion based neutral beam injector
Nuclear Fusion, 2019Co-Authors: K Ikeda, K Tsumori, H Nakano, M Kisaki, Kenichi Nagaoka, S Kamio, Y Fujiwara, Y Haba, M OsakabeAbstract:The achievements of the deuterium beam operatIon of a negative-Ion-based neutral beam injector (N-NBI) in the large helical device (LHD) are reported. In beam operatIon in LHD-NBIs, both hydrogen (H) and deuterium (D) neutral beams were generated by changing the operatIon gas using the same accelerator. The maximum accelerated deuterium negative-Ion current () reaches 46.2 A from two beam sources with the averaged current Density being 190 A m−2 for 2 s, and the extracted electron to accelerated Ion current ratio () increases to 0.39 using 5.6 V high bias voltage in the first deuterium operatIon in 2017. An increase of electron Density in the vicinity of the plasma grid (PG) surface, which is considered the main reason for the increase of co-extracted electrons in a beam, is confirmed by the half-size research negative-Ion source in the neutral beam test stand at the NatIonal Institute for FusIon Science (NIFS). The deuterium negative-Ion Density is also larger than the hydrogen negative-Ion Density in the vicinity of the PG surface using the same discharge conditIons. In the latest experimental campaign in 2018, increases to 55.4 A with the averaged current Density being 233 A m−2 for 1.5 s using the shot extractIon gap length. The low of 0.31 can be maintained by using high discharge power. The various parameters mentIoned above are defined in detail below.
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high Ion temperature experiments with negative Ion based neutral beam injectIon heating in large helical device
Nuclear Fusion, 2005Co-Authors: Y Takeiri, S Morita, K Tsumori, K Ikeda, M Osakabe, K Nagaoka, M Goto, J Miyazawa, S Masuzaki, N AshikawaAbstract:High-Z plasmas have been produced with Ar and/or Ne gas fuelling to increase the Ion temperature in Large Helical Device (LHD) plasmas heated with high-energy negative-Ion-based neutral beam injectIon (NBI). Although the electron heating is dominant in the high-energy NBI heating, the direct Ion heating power is significantly enhanced in low-Density plasmas due to both an increase in the beam absorptIon (IonizatIon) power and a reductIon of the Ion Density in the high-Z plasmas. Intensive neon- and/or argon-glow discharge cleaning works well to suppress dilutIon of the high-Z plasmas with wall-absorbed hydrogen. As a result, the Ion temperature increases with an increase in the Ion heating power normalized by the Ion Density and reaches 10 keV. An increase in the Ion temperature is also observed with the additIon of centrally focused electron cyclotron resonance heating to a low-Density and high-Z NBI plasma, suggesting improvement of the Ion transport. The results obtained in the high-Z plasma experiments with high-energy NBI heating suggest that an increase in the direct Ion heating power and improvement of the Ion transport are essential to Ion temperature rise, and that a high-Ion temperature could be obtained as well in hydrogen plasmas with low-energy positive-NBI heating which is planned in the near future in the LHD.
