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Journal Articles

Determination of tungsten and molybdenum concentrations from an X-ray range spectrum in JET with the ITER-like wall configuration

Nakano, Tomohide; Shumack, A.*; Maggi, C. F.*; Reinke, M.*; Lawson, K.*; Coffey, I.*; P$"u$tterich, T.*; Brezinsek, S.*; Lipschultz, B.*; Matthews, G. F.*; et al.

Journal of Physics B; Atomic, Molecular and Optical Physics, 48(14), p.144023_1 - 144023_11, 2015/07

 Times Cited Count:27 Percentile:84.61(Optics)

The $$mbox{W}^{45+}$$ and $$mbox{W}^{46+}$$ 3p-4d inner shell excitation lines in addition to $$mbox{Mo}^{32+}$$ 2p-3s lines have been identified from the spectrum taken by an upgraded high-resolution X-ray spectrometer. It is found from analysis of the absolute intensities of the $$mbox{W}^{46+}$$ and $$mbox{Mo}^{32+}$$ lines that W and Mo concentrations are in the range of $$sim10^{-5}$$ and $$sim10^{-6}$$, respectively, with a ratio of $$sim$$ 5% for ELMy H-mode plasmas with a plasma current of 2.0- 2.5 MA, a toroidal magnetic field of 2.7 T and a neutral beam injection power of 14-18 MW. For the purpose of checking self-consistency, it is confirmed that the W concentration determined from the $$mbox{W}^{45+}$$ line is in agreement with that from the $$mbox{W}^{46+}$$ line within 20% and that the plasma effective charge determined from the continuum of the first order reflection spectrum is also in agreement with that from the second order within 50%. Further, the determined plasma effective charge is in agreement with that determined from a visible spectroscopy, confirming that the sensitivity of the X-ray spectrometer is valid and that probably the W and the Mo concentrations are also valid.

Journal Articles

Determination of tungsten and molybdenum concentrations from an X-ray range spectrum in JET

Nakano, Tomohide; Shumack, A. E.*; Maggi, C.*; Reinke, M.*; Lawson, K. D.*; P$"u$tterich, T.*; Brezinsek, S.*; Lipschultz, B.*; Matthews, G.*; Chernyshova, M.*; et al.

Europhysics Conference Abstracts (Internet), 38F, p.P1.019_1 - P1.019_4, 2014/06

no abstracts in English

Journal Articles

Progress in the ITER physics basis, 1; Overview and summary

Shimada, Michiya; Campbell, D. J.*; Mukhovatov, V.*; Fujiwara, Masami*; Kirneva, N.*; Lackner, K.*; Nagami, Masayuki; Pustovitov, V. D.*; Uckan, N.*; Wesley, J.*; et al.

Nuclear Fusion, 47(6), p.S1 - S17, 2007/06

 Times Cited Count:624 Percentile:99.93(Physics, Fluids & Plasmas)

The Progress in the ITER Physics Basis document is an update of the ITER Physics Basis (IPB), which was published in 1999. The IPB provided methodologies for projecting the performance of burning plasmas, developed largely through coordinated experimental, modeling and theoretical activities carried out on today's tokamaks (ITER Physics R&D). In the IPB, projections for ITER (1998 Design) were also presented. The IPB also pointed out some outstanding issues. These issues have been addressed by the International Tokamak Physics Activities (ITPA), which were initiated by the European Union, Japan, Russia and the U.S.A.. The new methodologies of projection and control developed through the ITPA are applied to ITER, which was redesigned under revised technical objectives, but will nonetheless meet the programmatic objective of providing an integrated demonstration of the scientific and technological feasibility of fusion energy.

Journal Articles

Progress in the ITER physics basis, 4; Power and particle control

Loarte, A.*; Lipschultz, B.*; Kukushkin, A. S.*; Matthews, G. F.*; Stangeby, P. C.*; Asakura, Nobuyuki; Counsell, G. F.*; Federici, G.*; Kallenbach, A.*; Krieger, K.*; et al.

Nuclear Fusion, 47(6), p.S203 - S263, 2007/06

 Times Cited Count:726 Percentile:96.49(Physics, Fluids & Plasmas)

Progress, since the ITER Physics Basis publication (1999), in understanding the processes that will determine the properties of the plasma edge and its interaction with material elements in ITER is described. Significant progress in experiment area: energy and particle transport, the interaction of plasmas with the main chamber material elements, ELM energy deposition on material elements and the transport mechanism, the physics of plasma detachment and neutral dynamics, the erosion of low and high Z materials, their transport to the core plasma and their migration at the plasma edge, retention of tritium in fusion devices and removal methods. This progress has been accompanied by the development of modelling tools for the physical processes at the edge plasma and plasma-materials interaction. The implications for the expected performance in ITER and the lifetime of the plasma facing materials are discussed.

Journal Articles

Plasma-surface interaction, scrape-off layer and divertor physics; Implications for ITER

Lipschultz, B.*; Asakura, Nobuyuki; Bonnin, X.*; Coster, D. P.*; Counsell, G.*; Doerner, R.*; Dux, R.*; Federici, G.*; Fenstermacher, M. E.*; Fundamenski, W.*; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03

The work of the ITPA SOL/divertor group is reviewed. The high-n nature of ELMs has been elucidated and new measurements have determined that they carry 10-20% of the ELM energy to the far SOL with implications for ITER limiters and the upper divertor. Analysis of ELM measurements imply that the ELM continuously loses energy as it travels across the SOL. The prediction of ITER divertor disruption power loads have been reduced as a result of finding that the divertor footprint broadens during the thermal quench and that the plasma can lose up to 80% of its thermal energy before the thermal quench (not for VDEs or ITBs). Disruption mitigation through massive gas puffing has been successful at reducing divertor heat loads but estimates of the effect on the main chamber walls indicate 10s of kG of Be would be melted/mitigation. Long-pulse studies have shown that the fraction of injected gas that can be recovered after a discharge decreases with discharge length. The use of mixed materials gives rise to a number of potential processes.

Journal Articles

Progress in physics basis and its impact on ITER

Shimada, Michiya; Campbell, D.*; Stambaugh, R.*; Polevoi, A. R.*; Mukhovatov, V.*; Asakura, Nobuyuki; Costley, A. E.*; Donn$'e$, A. J. H.*; Doyle, E. J.*; Federici, G.*; et al.

Proceedings of 20th IAEA Fusion Energy Conference (FEC 2004) (CD-ROM), 8 Pages, 2004/11

This paper summarises recent progress in the physics basis and its impact on the expected performance of ITER. Significant progress has been made in many outstanding issues and in the development of hybrid and steady state operation scenarios, leading to increased confidence of achieving ITER's goals. Experiments show that tailoring the current profile can improve confinement over the standard H-mode and allow an increase in beta up to the no-wall limit at safety factors $$sim$$ 4. Extrapolation to ITER suggests that at the reduced plasma current of $$sim$$ 12MA, high Q $$>$$ 10 and long pulse ($$>$$1000 s) operation is possible with benign ELMs. Analysis of disruption scenarios has been performed based on guidelines on current quench rates and halo currents, derived from the experimental database. With conservative assumptions, estimated electromagnetic forces on the in-vessel components are below the design target values, confirming the robustness of the ITER design against disruption forces.

Journal Articles

Studies of ELM heat load, SOL flow and carbon erosion from existing Tokamak experiments, and projections for ITER

Asakura, Nobuyuki; Loarte, A.*; Porter, G.*; Philipps, V.*; Lipschultz, B.*; Kallenbach, A.*; Matthews, G.*; Federici, G.*; Kukushkin, A.*; Mahdavi, A.*; et al.

IAEA-CN-94/CT/P-01, 5 Pages, 2002/00

Three important physics issues for the ITER divertor design and operation are summarized based on the experimental and numerical work from multi-machine database (JET, JT-60U, ASDEX Upgrade, DIII-D, Alcator C-Mod and TEXTOR). (i) The energy load associated with Type-I ELMs is of great concern for the lifetime of the ITER divertor target. In order to understand the physics base of the scaling models, the ELM heat and particle transport to the divertor is investigated. Convective transport during ELMs plays an important role in heat transport to the divertor. (ii) Determination of the SOL flow pattern and the driving mechanism has progressed experimentally and numerically. Influences of the drift effects on the SOL and divertor plasma transport were discussed. (iii) Characteristics of chemical yield at two different deposited carbon surfaces, i.e. erosion- and redeposition-dominated areas, have been studied. Progress of understanding the chemical erosion is reviewed.

Oral presentation

Determination of tungsten and molybdenum concentrations from an X-ray range spectrum in JET

Nakano, Tomohide; Shumack, A.*; Maggi, C. F.*; Reinke, M.*; Lawson, K.*; P$"u$tterich, T.*; Brezinsek, S.*; Lipschultz, B.*; Matthews, G. F.*; Chernyshova, M.*; et al.

no journal, , 

In an European tokamak device, JET, an existing high-resolution X-ray crystal spectrometer was upgraded together with installation of the W divertor for the purpose of monitoring the W density in the core plasma. We have identified W$$^{46+}$$, W$$^{45+}$$ and Mo$$^{32+}$$ lines by comparing the spectrum observed by this spectrometer and that calculated by an atomic structure code. Further, from the intensities of these spectral lines, the W density and the Mo density over an electron density were determined to be $$10^{-5}$$ and $$10^{-7}$$, respectively. The determined W density was in good agreement with that from another spectrometer. In addition, the plasma effective charge evaluated from the continuum intensity observed by the X-ray spectrometer was in agreement with that from a visible spectrometer within a factor of three. From these agreements, it is probable that the determined W and Mo density are valid. In contrast, the determined W density is only 15% compared with that from an soft X-ray array measurement. This inconsistency will be investigated in the near future.

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