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Helium Transport Studies On Diii D
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Book Synopsis Helium Transport Studies on DIII-D. by :
Download or read book Helium Transport Studies on DIII-D. written by and published by . This book was released on 1992 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The measurement of Helium density profiles in tokamak plasmas is necessary for helium transport studies. These studies are important in predicting the helium ash transport properties for ITER and win have important implications for the design. Poor helium transport in reactors could lead to a buildup of fusion ash, causing fuel dilution and increased radiation that will result in degraded fusion power and possibly quench ignition altogether. Present estimates indicate that He concentrations in the core must be kept below 10% in order to maintain continuous reactor operation. Helium transport studies have begun on the DM-D tokamak using charge exchange recombination (CER) spectroscopy for helium density measurements. Helium transport behavior has been observed by injecting helium gas puffs into DM-D plasmas and measuring the He density profile evolution. The profiles are used to calculate the relevant helium transport properties. This paper covers the results obtained from puffing He gas into L-mode plasmas of various electron densities. The results obtained in DIII-D L-mode plasmas are similar to measurements made at TEXTOR and JT-60.
Book Synopsis Helium Transport and Exhaust Studies in Enhanced Confinement Regimes in DIII-D. by :
Download or read book Helium Transport and Exhaust Studies in Enhanced Confinement Regimes in DIII-D. written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A better understanding of helium transport in the plasma core and edge in enhanced confinement regimes is now emerging from recent experimental studies on DIII-D. Overall, the results are encouraging. Significant helium exhaust ([tau]*[sub He]/[tau][sub E][approximately] 11) has been obtained in a diverted, ELMing H-mode plasma simultaneous with a central source of helium. Detailed analysis of the helium profile evolution indicates that the exhaust rate is limited by the exhaust efficiency of the pump ([approximately]5%) and not by the intrinsic helium transport properties of the plasma. Perturbative helium transport studies using gas puffing have shown that D[sub He]/X[sub eff][approximately]1 in all confinement regimes studied to date (including H-mode and VH-mode). Furthermore, there is no evidence of preferential accumulation of helium in any of these regimes. However, measurements in the core and pumping plenum show a significant dilution of helium as it flows from the plasma core to the pumping plenum. Such dilution could be the limiting factor in the overall removal rate of helium in a reactor system.
Book Synopsis Helium Transport and Exhaust Studies of H-mode Discharges in the DIII-D Tokamak by :
Download or read book Helium Transport and Exhaust Studies of H-mode Discharges in the DIII-D Tokamak written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A collaborative program has been initiated to measure helium (He) transport and exhaust on DIII-D in L-mode, ELM-free H-mode, and ELMing H-mode. These diverted plasmas operating in enhanced confinement regimes should provide valuable information for the International Thermonuclear Experimental Reactor (ITER). To simulate the presence of He ash in DIII-D, a 50 ms He puff is injected into a DIII-D plasma, resulting in a He concentration of [approximately] 15%. The time dependence of the He density profiles in the plasma core is measured with charge-exchange recombination spectroscopy and the He spatial distribution on the diverter floor is studied with an impurity monitor array. The dependence of core transport diffusivities as a function of ELM frequency have been studied and the first demonstration made of He exhaust from an H-mode plasma in a diverted tokamak. The exhaust rate of He from these ELMing H-mode plasmas appears to be within the acceptable range for a fusion reactor, like ITER, based on a measured value of [tau]*[sub He]/[tau]E [approx]14.
Book Synopsis Helium Transport in Enhanced Confinement Regimes on the TEXTOR and DIII-D Tokamaks by :
Download or read book Helium Transport in Enhanced Confinement Regimes on the TEXTOR and DIII-D Tokamaks written by and published by . This book was released on 1992 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comparisons of helium (He) transport and exhaust in L-mode and in an enhanced confinement regime (H-mode), which is induced by a polarizing electrode, have been made for the TEXTOR tokamak. The results show an increased tendency for He accumulation when bulk plasma energy and particle confinement are improved during the polarization induced H-mode. Since these results imply that a high He pumping efficiency may be necessary for H-mode burning plasmas, we have begun exploring He transport in a divertor H-mode, similar to that proposed for International Thermonuclear Experimental Reactor (ITER). A collaborative program has been initiated to measure He transport and scaling on DIII-D during L-mode, H-mode, and ELMing H-mode plasma conditions. To simulate the presence of He ash in DIII-D, a 25 ms He puff is injected into a DIII-D plasma resulting in a He concentration of (almost equal to)5%. The time dependence of the He{sup 2+} density profiles in the plasma core is measured by charge-exchange recombination spectroscopy at 11 radial locations.
Book Synopsis Helium Exhaust Studies in the DIII-D Tokamak by :
Download or read book Helium Exhaust Studies in the DIII-D Tokamak written by and published by . This book was released on 1994 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Significant exhaust of thermal helium in a diverted, H-mode deuterium plasma has been demonstrated for the first time on the DIII-D tokamak using an in-vessel cryopump conditioned with an argon frost. The helium, introduced via gas puffing, is observed to reach the plasma core and then is readily removed from the plasma with a time constant of (approximately)8-15 energy confinement times. Detailed analysis of the helium profile evolution indicates that the exhaust rate is limited by the exhaust efficiency of the pump ((approximately)5%) and not by the intrinsic helium transport properties of the plasma. Additional studies focusing on the recycling properties of helium relative to deuterium in the divertor region indicate some dependence of the helium concentration in the divertor pumping plenum on the divertor outer strike-point (OSP) position in Ohmic discharges. However, the helium concentration in the plenum appears to have little dependence on OSP position in beam-heated, ELMing H-mode discharges.
Book Synopsis Overview of H-mode Studies in DIII-D. by :
Download or read book Overview of H-mode Studies in DIII-D. written by and published by . This book was released on 1994 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: A major portion of the DIII-D program includes studies of the L-H transition, of the VH-mode, of particle transport and control and of the power-handling capability of a diverter. Significant progress has been made in all of these areas and the purpose of this paper is to summarize the major results obtained during the last two years. An increased understanding of the origin of improved confinement in H-mode and in VH-mode discharges has been obtained, good impurity control has been achieved in several operating scenarios, studies of helium transport provide encouraging results from the point of view of reactor design, an actively pumped diverter chamber has controlled the density in H-mode discharges and a radiative diverter is a promising technique for controlling the heat flux from the main plasma.
Book Synopsis Beiträge zur antiautoritären Erziehung by :
Download or read book Beiträge zur antiautoritären Erziehung written by and published by . This book was released on 1969 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dependence of Helium Transport on Plasma Current and ELM Frequency in H-mode Discharges in DIII-D. by :
Download or read book Dependence of Helium Transport on Plasma Current and ELM Frequency in H-mode Discharges in DIII-D. written by and published by . This book was released on 1993 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The removal of helium (He) ash from the plasma core with high efficiency to prevent dilution of the D-T fuel mixture is of utmost importance for future fusion devices, such as the International Thermonuclear Experimental Reactor (ITER). A variety of measurements in L-mode conditions have shown that the intrinsic level of helium transport from the core to the edge may be sufficient to prevent sufficient dilution (i.e., [tau]{sub He} /[tau]{sub E}
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Measurement of Absolute Helium Ion Density Profiles on the DIII-D Tokamak Using Charge Exchange Recombination Spectroscopy by : Daniel Franklin Finkenthal
Download or read book The Measurement of Absolute Helium Ion Density Profiles on the DIII-D Tokamak Using Charge Exchange Recombination Spectroscopy written by Daniel Franklin Finkenthal and published by . This book was released on 1994 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tokamaks written by John Wesson and published by Oxford University Press. This book was released on 2011-10-13 with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt: The tokamak is the principal tool in controlled fusion research. This book acts as an introduction to the subject and a basic reference for theory, definitions, equations, and experimental results. The fourth edition has been completely revised, describing their development of tokamaks to the point of producing significant fusion power.
Book Synopsis Review by : Oak Ridge National Laboratory
Download or read book Review written by Oak Ridge National Laboratory and published by . This book was released on 1996 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-05 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis UEDGE Simulations of He Transport in DIII-D Progress Report FY 1996 by :
Download or read book UEDGE Simulations of He Transport in DIII-D Progress Report FY 1996 written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this report we present the status of numerical simulations of helium exhaust efficiency in the DIII-D tokamak. These computations are intended to serve eventually as a benchmark for simulations carried out for the ITER divertor geometry. Helium ash removal is an important issue for ITER since the helium ash can dilute the central fuel concentration and reduce the fusion power. Present experiments have shown that helium transport in the core plasma is sufficiently rapid to limit the ash buildup to acceptable levels if sufficient helium pumping can be maintained in the divertor. The question of pumping helium gas from the divertor has also been addressed in tokamak experiments, where it was found that the helium concentration in the divertor was about 5-10[times] lower than in the core plasma (deenrichment). Even so, the exhaust rate was adequate to meet the ITER requirements for central helium concentration. However, the experiments did not reproduce the anticipated ITER divertor geometry or operating conditions. Therefore, the predicted helium exhaust for ITER is still based on numerical simulation. In order to increase the confidence level in the simulations of helium exhaust in ITER, we decided to test the ability of the UEDGE code to simulate the measured enrichment of divertor helium in the DIII-D pumping plenum. Section II presents a description of the experimental discharge used for comparison with the present UEDGE simulations. The UEDGE runs which most closely match the data are presented in Section III including simulations with and without carbon impurity. Section IV presents UEDGE simulations of helium transport and comparison with the helium measurements for these discharges. Conclusions and plans for future work, to complete the detailed benchmarking of UEDGE helium transport models, are given in Section V. 6 refs., 26 figs., 1 tab.
Download or read book Nuclear Fusion written by and published by . This book was released on 2005 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Plasma Physics and Controlled Nuclear Fusion Research by :
Download or read book Plasma Physics and Controlled Nuclear Fusion Research written by and published by . This book was released on 1994 with total page 838 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :United States. Congress. House. Committee on Science. Subcommittee on Energy and Environment Publisher : ISBN 13 : Total Pages :682 pages Book Rating :4.3/5 (121 download)
Book Synopsis The Department of Energy's Restructured Fusion Energy Sciences Program by : United States. Congress. House. Committee on Science. Subcommittee on Energy and Environment
Download or read book The Department of Energy's Restructured Fusion Energy Sciences Program written by United States. Congress. House. Committee on Science. Subcommittee on Energy and Environment and published by . This book was released on 1996 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt:
