The Back Transition and Hysteresis Effects in DIII-D. PDF Download
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Languages : en
Pages : 14
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The back transition from H-mode to L-mode has been studied on DIII-D as a part of the investigation of the L-H transition power threshold scaling. Based on a density-dependent scaling for the H-mode power threshold, ITER will require substantial hysteresis in this parameter to remain in H-mode as n{sub e} rises. Defining the hysteresis in terms of the ratio of sustaining to threshold power, P{sub HL}/P{sub LH} may need to be as small as 50% for ITER. Operation of DIII-D at injection powers slightly above the H-mode threshold results in an oscillatory behavior with multiple forward-backward transitions in the course of a discharge. These discharges represent a unique system for studying various control parameters that may influence the H↔L state transition. Careful analysis of the power flow through the edge gives values for the sustaining power which are well below the corresponding threshold powers (P{sub HL}/P{sub LH} = 35--70%), indicating substantial hysteresis can be achieved in this parameter. Studies of other control parameter candidates such as edge temperature during the back transitions are less clear: the amount of hysteresis seen in these parameters, if any, is primarily dependent on the nature (ELMing, ELM-free) of the parent H-state.
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Category :
Languages : en
Pages : 14
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Book Description
The back transition from H-mode to L-mode has been studied on DIII-D as a part of the investigation of the L-H transition power threshold scaling. Based on a density-dependent scaling for the H-mode power threshold, ITER will require substantial hysteresis in this parameter to remain in H-mode as n{sub e} rises. Defining the hysteresis in terms of the ratio of sustaining to threshold power, P{sub HL}/P{sub LH} may need to be as small as 50% for ITER. Operation of DIII-D at injection powers slightly above the H-mode threshold results in an oscillatory behavior with multiple forward-backward transitions in the course of a discharge. These discharges represent a unique system for studying various control parameters that may influence the H↔L state transition. Careful analysis of the power flow through the edge gives values for the sustaining power which are well below the corresponding threshold powers (P{sub HL}/P{sub LH} = 35--70%), indicating substantial hysteresis can be achieved in this parameter. Studies of other control parameter candidates such as edge temperature during the back transitions are less clear: the amount of hysteresis seen in these parameters, if any, is primarily dependent on the nature (ELMing, ELM-free) of the parent H-state.
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Category :
Languages : en
Pages : 15
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Author: Irina Gruzinov
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Category :
Languages : en
Pages : 208
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Category :
Languages : en
Pages : 8
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Studies have been conducted in DIII-D to determine the dependence of the power threshold P{sub lh} for the transition to the H-mode regime and the threshold P{sub hl} for the transition from H-mode to L-mode as functions of external parameters. There is a value of the line-averaged density n{sub e} at which P{sub lh} has a minimum and P{sub lh} tends to increase for lower and higher values of n{sub e}. Experiments conducted to separate the effect of the neutral density n0 from the plasma density n{sub e} give evidence of a strong coupling between n0 and n{sub e}. The separate effect of neutrals on the transition has not been determined. Coordinated experiments with JET made in the ITER shape show that P{sub lh} increases approximately as S{sup 0.5} where S is the plasma surface area. For these discharges, the power threshold in DIII-D was high by normal standards, thus suggesting that effects other than plasma size may have affected the experiment. Studies of H-L transitions have been initiated and hysteresis of order 40% has been observed. Studies have also been done of the dependence of the L-H transition on local edge parameters. Characterization of the edge within a few ms prior to the transition shows that the range of edge temperatures at which the transition has been observed is more restrictive than the range of densities at which it occurs. These results suggest that some temperature function is important for controlling the transition.
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Category : Controlled fusion
Languages : en
Pages : 962
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Book Description
Author: International Atomic Energy Agency
Publisher: Fusion Energy 1996
ISBN: 9789201007971
Category : Business & Economics
Languages : en
Pages : 954
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Book Description
Proceedings of the Sixteenth International Conference, formerly called the International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Montreal, 7-11 October 1996. The papers presented reflect the excellent progress achieved since the last conference in Seville 1994. Among many other achievements, the Tokamak Fusion Test Reactor has produced over 10 MW of fusion power, the JT-60U experiment has demonstrated plasma conditions equivalent to breakeven, the reversed shear mode has been demonstrated, low aspect ratio tokamaks have produced promising results and plans have been drawn up for powerful new inertial confinement fusion experiments.
Author: Philipp Gütlich
Publisher: Springer Science & Business Media
ISBN: 9783540403944
Category : Science
Languages : en
Pages : 640
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Book Description
With contributions by numerous experts
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ISBN:
Category : Fusion reactors
Languages : en
Pages : 292
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Book Description
Author: Boris Galperin
Publisher: Cambridge University Press
ISBN: 1107043883
Category : Nature
Languages : en
Pages : 527
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Book Description
Presents a comprehensive, multidisciplinary volume on the physics of zonal jets, from the leading experts, for graduate students and researchers.
Author: M. A. Cayless
Publisher: Routledge
ISBN: 0415503086
Category : Electric lamps
Languages : en
Pages : 553
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Book Description
This book is a comprehensive guide to the theory and practice of lighting. Covering the physics of light production, light sources, circuits and a wide variety of lighting applications, it is both suitable as a detailed textbook and as thoroughly practical guide for practising lighting engineers. This fourth edition of Lamps and Lighting has been completely updated with new chapters on the latest lamp technology and applications. The editors ahve called upon a wide range of expertise and as a result many sections have been broadened to include both European and US practice. The book begins with a description of the fundamentals of light, vision, colour and measurement. Part II, the main section of the book, deals with lamps and control equipment and includes descriptions of all lamp types in use today. Part III on lighting covers both interior and exterior applications.
