The Experts below are selected from a list of 156 Experts worldwide ranked by ideXlab platform
U. Fantz - One of the best experts on this subject based on the ideXlab platform.
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size scaling of negative Hydrogen Ion sources for fusIon
FOURTH INTERNATIONAL SYMPOSIUM ON NEGATIVE IONS BEAMS AND SOURCES (NIBS 2014), 2015Co-Authors: U. Fantz, P Franzen, L Schiesko, C Wimmer, W Kraus, D WunderlichAbstract:The RF-driven negative Hydrogen Ion source (H−, D−) for the internatIonal fusIon experiment ITER has a width of 0.9 m and a height of 1.9 m and is based on a ⅛ scale prototype source being in operatIon at the IPP test facilities BATMAN and MANITU for many years. Among the challenges to meet the required parameters in a caesiated source at a source pressure of 0.3 Pa or less is the challenge in size scaling of a factor of eight. As an intermediate step a ½ scale ITER source went into operatIon at the IPP test facility ELISE with the first plasma in February 2013. The experience and results gained so far at ELISE allowed a size scaling study from the prototype source towards the ITER relevant size at ELISE, in which operatIonal issues, physical aspects and the source performance is addressed, highlighting differences as well as similarities. The most ITER relevant results are: low pressure operatIon down to 0.2 Pa is possible without problems; the magnetic filter field created by a current in the plasma gri...
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on the proton flux toward the plasma grid in a rf driven negative Hydrogen Ion source for iter nbi
Plasma Physics and Controlled Fusion, 2012Co-Authors: D Wunderlich, P Franzen, P Mcneely, L Schiesko, U. Fantz, Nnbi TeamAbstract:The transport of protons in a RF-driven negative Hydrogen Ion source for ITER NBI was investigated by means of a 3D Monte Carlo transport code. As input for the code a consistent axial profile of the electrostatic potential for the complete Ion source was constructed. The potential difference between the plasma generatIon volume and the plasma grid is in the range 10?20?V and depends on the RF power, the filling pressure and the plasma grid bias voltage. The mean free path for proton collisIons with the background gas is in the range of several centimeters which means that the protons are noticeably decelerated and scattered. The velocity distributIon functIon of the protons impinging the plasma grid resembles much more a low-temperature Maxwell distributIon functIon than the high energetic proton beam which would be expected by looking only at the maximum value of the potential in the plasma generatIon volume. This finding is of high relevance for further analysis of the negative Hydrogen Ion productIon on the plasma grid surface as well as the Ion transport and beam formatIon.
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magnetic field dependance of the plasma properties in a negative Hydrogen Ion source for fusIon
Plasma Physics and Controlled Fusion, 2012Co-Authors: L Schiesko, P Franzen, P Mcneely, U. Fantz, N I TeamAbstract:Axially resolved measurements of plasma parameters were performed by two Langmuir probes moving in parallel from the exit of the driver (where the plasma is generated) up to the extractIon regIon neighbourhood of the IPP RF negative Hydrogen Ion source prototype. At the driver exit, the plasma parameters show an unexpected inhomogeneity in the presence of the magnetic field: a cold and dense plasma flows out of the top part of the driver while a hot and low density plasma flows from the bottom part. A local relatIon between the top and bottom parameters is derived from the conservatIon of the energy flux.
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development of negative Hydrogen Ion sources for fusIon experiments and modelling
Chemical Physics, 2012Co-Authors: U. Fantz, P Franzen, D WunderlichAbstract:Abstract Large and powerful negative Hydrogen Ion sources have to be developed for the neutral beam injectIon system of the internatIonal fusIon experiment ITER which is currently under constructIon. In order to fulfil the ITER requirements — high negative Ion current densities and low co-extracted electron currents at low pressure operatIon (0.3 Pa) — caesium is seeded into the discharges which lowers the work functIon of the converter surface. The paper addresses the development program at the three test facilities of the Max-Planck-Institut fur Plasmaphysik (IPP) in Garching. Emphasis is given on a comparison of deuterium with Hydrogen operatIon as well as on the complex caesium chemistry and the plasma surface interactIon which are at present the most critical issues for optimising the source performance. An insight into the plasma chemistry and the processes relevant for source optimisatIon is provided by the well diagnosed plasma accompanied by modelling which is strongly coupled to the physics relevant for the experiments.
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cavity ring down system for density measurement of negative Hydrogen Ion on negative Ion source
SECOND INTERNATIONAL SYMPOSIUM ON NEGATIVE IONS BEAMS AND SOURCES, 2011Co-Authors: H Nakano, U. Fantz, K Tsumori, Kenichi Nagaoka, M Shibuya, M Kisaki, Katsunori Ikeda, M Osakabe, O Kaneko, E AsanoAbstract:A Cavity Ring‐Down (CRD) system was applied to measure the density of negative Hydrogen Ion (H−) in vicinity of extractIon surface in the H− source for the development of neutral beam injector on Large Helical Device (LHD). The density measurement with sampling time of 50 ms was carried out. The measured density with the CRD system is relatively good agreement with the density evaluated from extracted beam‐current with applying a similar relatIon of positive Ion sources. In cesium seeded into Ion‐source plasma, the linearity between an arc power of the discharge and the measured density with the CRD system was observed. AdditIonally, the measured density was proportIonal to the extracted beam current. These characteristics indicate the CRD system worked well for H− density measurement in the regIon of H− and extractIon.
N I Team - One of the best experts on this subject based on the ideXlab platform.
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magnetic field dependance of the plasma properties in a negative Hydrogen Ion source for fusIon
Plasma Physics and Controlled Fusion, 2012Co-Authors: L Schiesko, P Franzen, P Mcneely, U. Fantz, N I TeamAbstract:Axially resolved measurements of plasma parameters were performed by two Langmuir probes moving in parallel from the exit of the driver (where the plasma is generated) up to the extractIon regIon neighbourhood of the IPP RF negative Hydrogen Ion source prototype. At the driver exit, the plasma parameters show an unexpected inhomogeneity in the presence of the magnetic field: a cold and dense plasma flows out of the top part of the driver while a hot and low density plasma flows from the bottom part. A local relatIon between the top and bottom parameters is derived from the conservatIon of the energy flux.
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laser photodetachment on a high power low pressure rf driven negative Hydrogen Ion source
Plasma Sources Science and Technology, 2009Co-Authors: S Christkoch, U. Fantz, M Berger, N I TeamAbstract:Powerful, low pressure negative Hydrogen Ion sources are a basic component of future neutral beam heating systems for fusIon devices. The required high Ion currents (>40?A) are obtained via the surface productIon process, which requires negative Ion densities in the range of in the plasma regIon close to the extractIon system. For spatially resolved diagnostics of the negative Hydrogen Ion densities, the laser photodetachment method has been applied to a high power, low pressure, rf-driven Ion source (150?kW, 0.3?Pa) for the first time. The diagnostic setup and the data evaluatIon had to cope with the rf field (1?MHz), the high source potential during extractIon (?25?kV) and the presence of magnetic fields (<10?mT). Horizontal profiles of negative Ion densities and electron densities along 15?cm with a typical step length of 1?cm and a probe tip of 5?mm length show a broad maximum in the centre of the extractIon regIon. The variatIon of a bias voltage applied to the plasma grid with respect to the source body yields a correlatIon between the detachment signals for the negative Ion density and the electron density with the extracted Ion and electron currents, respectively. The density ratio of negative Hydrogen Ions to electrons is in the range of , demonstrating that the negative Ions are the dominant negatively charged species in these types of Ion sources. Absolute negative Ion densities are in good agreement with line-of-sight integrated results of cavity ring-down spectroscopy and optical emissIon spectroscopy.
Nnbi Team - One of the best experts on this subject based on the ideXlab platform.
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on the proton flux toward the plasma grid in a rf driven negative Hydrogen Ion source for iter nbi
Plasma Physics and Controlled Fusion, 2012Co-Authors: D Wunderlich, P Franzen, P Mcneely, L Schiesko, U. Fantz, Nnbi TeamAbstract:The transport of protons in a RF-driven negative Hydrogen Ion source for ITER NBI was investigated by means of a 3D Monte Carlo transport code. As input for the code a consistent axial profile of the electrostatic potential for the complete Ion source was constructed. The potential difference between the plasma generatIon volume and the plasma grid is in the range 10?20?V and depends on the RF power, the filling pressure and the plasma grid bias voltage. The mean free path for proton collisIons with the background gas is in the range of several centimeters which means that the protons are noticeably decelerated and scattered. The velocity distributIon functIon of the protons impinging the plasma grid resembles much more a low-temperature Maxwell distributIon functIon than the high energetic proton beam which would be expected by looking only at the maximum value of the potential in the plasma generatIon volume. This finding is of high relevance for further analysis of the negative Hydrogen Ion productIon on the plasma grid surface as well as the Ion transport and beam formatIon.
L Schiesko - One of the best experts on this subject based on the ideXlab platform.
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size scaling of negative Hydrogen Ion sources for fusIon
FOURTH INTERNATIONAL SYMPOSIUM ON NEGATIVE IONS BEAMS AND SOURCES (NIBS 2014), 2015Co-Authors: U. Fantz, P Franzen, L Schiesko, C Wimmer, W Kraus, D WunderlichAbstract:The RF-driven negative Hydrogen Ion source (H−, D−) for the internatIonal fusIon experiment ITER has a width of 0.9 m and a height of 1.9 m and is based on a ⅛ scale prototype source being in operatIon at the IPP test facilities BATMAN and MANITU for many years. Among the challenges to meet the required parameters in a caesiated source at a source pressure of 0.3 Pa or less is the challenge in size scaling of a factor of eight. As an intermediate step a ½ scale ITER source went into operatIon at the IPP test facility ELISE with the first plasma in February 2013. The experience and results gained so far at ELISE allowed a size scaling study from the prototype source towards the ITER relevant size at ELISE, in which operatIonal issues, physical aspects and the source performance is addressed, highlighting differences as well as similarities. The most ITER relevant results are: low pressure operatIon down to 0.2 Pa is possible without problems; the magnetic filter field created by a current in the plasma gri...
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on the proton flux toward the plasma grid in a rf driven negative Hydrogen Ion source for iter nbi
Plasma Physics and Controlled Fusion, 2012Co-Authors: D Wunderlich, P Franzen, P Mcneely, L Schiesko, U. Fantz, Nnbi TeamAbstract:The transport of protons in a RF-driven negative Hydrogen Ion source for ITER NBI was investigated by means of a 3D Monte Carlo transport code. As input for the code a consistent axial profile of the electrostatic potential for the complete Ion source was constructed. The potential difference between the plasma generatIon volume and the plasma grid is in the range 10?20?V and depends on the RF power, the filling pressure and the plasma grid bias voltage. The mean free path for proton collisIons with the background gas is in the range of several centimeters which means that the protons are noticeably decelerated and scattered. The velocity distributIon functIon of the protons impinging the plasma grid resembles much more a low-temperature Maxwell distributIon functIon than the high energetic proton beam which would be expected by looking only at the maximum value of the potential in the plasma generatIon volume. This finding is of high relevance for further analysis of the negative Hydrogen Ion productIon on the plasma grid surface as well as the Ion transport and beam formatIon.
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magnetic field dependance of the plasma properties in a negative Hydrogen Ion source for fusIon
Plasma Physics and Controlled Fusion, 2012Co-Authors: L Schiesko, P Franzen, P Mcneely, U. Fantz, N I TeamAbstract:Axially resolved measurements of plasma parameters were performed by two Langmuir probes moving in parallel from the exit of the driver (where the plasma is generated) up to the extractIon regIon neighbourhood of the IPP RF negative Hydrogen Ion source prototype. At the driver exit, the plasma parameters show an unexpected inhomogeneity in the presence of the magnetic field: a cold and dense plasma flows out of the top part of the driver while a hot and low density plasma flows from the bottom part. A local relatIon between the top and bottom parameters is derived from the conservatIon of the energy flux.
Glenn J.r. Whitman - One of the best experts on this subject based on the ideXlab platform.
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Influence of Hydrogen Ion concentratIon versus carbon dioxide tensIon on pulmonary vascular resistance after cardiac operatIon.
The Journal of Thoracic and Cardiovascular Surgery, 1993Co-Authors: David A. Fullerton, Lyle E. Kirson, T. Kinnard, Glenn J.r. WhitmanAbstract:Disturbances of respiratory acid-base status are common in patients supported with mechanical ventilatIon of the lungs after cardiac operatIons. This study was conducted with two protocols. The purpose was to determine whether respiratory acid-base status influences pulmonary vascular resistance in adults after cardiac operatIons and whether the influence is mediated by Hydrogen Ion concentratIon or carbon dioxide tensIon. Patients were studied while under general anesthesia immediately after aorta-coronary bypass. In the first protocol, with seven patients, arterial carbon dioxide tensIon was manipulated by the additIon of 5 % carbon dioxide to the breathing circuit. Pulmonary vascular resistance index was determined as arterial carbon dioxide tensIon rose from 30 mm Hg to 50 mm Hg and back to 30 mm Hg. In the second protocol, with 10 different patients, Hydrogen Ion concentratIon was manipulated by the additIon of 0.2N hydrochloric acid, sodium bicarbonate, or both as arterial carbon dioxide tensIon was held constant. We used analysis of variance for statistical data. The results of the first protocol showed that pulmonary vascular resistance index rose by 44 % (p
