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Carlstrom TN. L-H Transition and Power Threshold Studies in the DIII-D Tokamak. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst05-a1055] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- T. N. Carlstrom
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
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2
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Stratton BC, Bitter M, Hill KW, Hillis DL, Hogan JT. Chapter 5: Passive Spectroscopic Diagnostics for Magnetically Confined Fusion Plasmas. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst08-a1677] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- B. C. Stratton
- Princeton Plasma Physics Laboratory Princeton University, Princeton, New Jersey 08543
| | - M. Bitter
- Princeton Plasma Physics Laboratory Princeton University, Princeton, New Jersey 08543
| | - K. W. Hill
- Princeton Plasma Physics Laboratory Princeton University, Princeton, New Jersey 08543
| | - D. L. Hillis
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - J. T. Hogan
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
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3
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Zhong WL, Shen Y, Zou XL, Gao JM, Shi ZB, Dong JQ, Duan XR, Xu M, Cui ZY, Li YG, Ji XQ, Yu DL, Cheng J, Xiao GL, Jiang M, Yang ZC, Zhang BY, Shi PW, Liu ZT, Song XM, Ding XT, Liu Y. Observation of Double Impurity Critical Gradients for Electromagnetic Turbulence Excitation in Tokamak Plasmas. PHYSICAL REVIEW LETTERS 2016; 117:045001. [PMID: 27494476 DOI: 10.1103/physrevlett.117.045001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Indexed: 06/06/2023]
Abstract
The impact of impurity ions on a pedestal has been investigated in the HL-2A Tokamak, at the Southwestern Institute of Physics, Chengdu, China. Experimental results have clearly shown that during the H-mode phase, an electromagnetic turbulence was excited in the edge plasma region, where the impurity ions exhibited a peaked profile. It has been found that double impurity critical gradients are responsible for triggering the turbulence. Strong stiffness of the impurity profile has been observed during cyclic transitions between the I-phase and H-mode regime. The results suggest that the underlying physics of the self-regulated edge impurity profile offers the possibility for an active control of the pedestal dynamics via pedestal turbulence.
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Affiliation(s)
- W L Zhong
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - Y Shen
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - X L Zou
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
| | - J M Gao
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - Z B Shi
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - J Q Dong
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
- Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - X R Duan
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - M Xu
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - Z Y Cui
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - Y G Li
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - X Q Ji
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - D L Yu
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - J Cheng
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - G L Xiao
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - M Jiang
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - Z C Yang
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - B Y Zhang
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - P W Shi
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - Z T Liu
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - X M Song
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - X T Ding
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - Yong Liu
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
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4
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Cheng J, Dong JQ, Itoh K, Yan LW, Xu M, Zhao KJ, Hong WY, Huang ZH, Ji XQ, Zhong WL, Yu DL, Itoh SI, Nie L, Kong DF, Lan T, Liu AD, Zou XL, Yang QW, Ding XT, Duan XR, Liu Y. Dynamics of low-intermediate-high-confinement transitions in toroidal plasmas. PHYSICAL REVIEW LETTERS 2013; 110:265002. [PMID: 23848884 DOI: 10.1103/physrevlett.110.265002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Indexed: 06/02/2023]
Abstract
The dynamic features of the low-intermediate-high-(L-I-H) confinement transitions on HL-2A tokamak are presented. Here we report the discovery of two types of limit cycles (dubbed type-Y and type-J), which show opposite temporal ordering between the radial electric field and turbulence intensity. In type-Y, which appears first after an L-I transition, the turbulence grows first, followed by the localized electric field. In contrast, the electric field leads type-J. The turbulence-induced zonal flow and pressure-gradient-induced drift play essential roles in the two types of limit cycles, respectively. The condition of transition between types-Y and -J is studied in terms of the normalized radial electric field. An I-H transition is demonstrated to occur only from type-J.
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Affiliation(s)
- J Cheng
- Southwestern Institute of Physics, Chengdu 610041, People's Republic of China
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5
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Schmitz L, Zeng L, Rhodes TL, Hillesheim JC, Doyle EJ, Groebner RJ, Peebles WA, Burrell KH, Wang G. Role of zonal flow predator-prey oscillations in triggering the transition to H-mode confinement. PHYSICAL REVIEW LETTERS 2012; 108:155002. [PMID: 22587261 DOI: 10.1103/physrevlett.108.155002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Indexed: 05/31/2023]
Abstract
Direct evidence of zonal flow (ZF) predator-prey oscillations and the synergistic roles of ZF- and equilibrium E×B flow shear in triggering the low- to high-confinement (L- to H-mode) transition in the DIII-D tokamak is presented. Periodic turbulence suppression is first observed in a narrow layer at and just inside the separatrix when the shearing rate transiently exceeds the turbulence decorrelation rate. The final transition to H mode with sustained turbulence and transport reduction is controlled by equilibrium E×B shear due to the increasing ion pressure gradient.
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Affiliation(s)
- L Schmitz
- University of California-Los Angeles, Los Angeles, California 90095, USA
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6
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Estrada T, Hidalgo C, Happel T, Diamond PH. Spatiotemporal structure of the interaction between turbulence and flows at the L-H transition in a toroidal plasma. PHYSICAL REVIEW LETTERS 2011; 107:245004. [PMID: 22243007 DOI: 10.1103/physrevlett.107.245004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Indexed: 05/31/2023]
Abstract
The spatiotemporal behavior of the interaction between turbulence and flows has been studied close to the L-H transition threshold conditions in the edge region (ρ≥0.7) of TJ-II plasmas. The temporal dynamics of the interaction displays an oscillatory behavior with a characteristic predator-prey relationship. The spatial evolution of this turbulence-flow oscillation pattern has been measured, showing both radial outward and inward propagation velocities of the turbulence-flow front. The results indicate that the edge shear flow linked to the L-H transition can behave either as a slowing-down, damping mechanism of outward propagating turbulent-flow oscillating structures, or as a source of inward propagating turbulence-flow events.
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Affiliation(s)
- T Estrada
- Laboratorio Nacional de Fusión, Asociación Euratom-CIEMAT, 28040, Madrid, Spain.
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7
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Kamiya K, Ida K, Sakamoto Y, Matsunaga G, Kojima A, Urano H, Oyama N, Koide Y, Kamada Y. Observation of a complex multistage transition in the JT-60U H-mode edge. PHYSICAL REVIEW LETTERS 2010; 105:045004. [PMID: 20867854 DOI: 10.1103/physrevlett.105.045004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Indexed: 05/29/2023]
Abstract
A complex multistage transition of the edge radial electric field is observed in JT-60U H-mode phase without edge localized mode. An interesting feature is that the poloidal rotation velocity of the carbon impurity ions changes in the later H-phase without a comparable change in the main ion pressure gradient, indicating a change in the parallel momentum (and particle) balance channel.
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Affiliation(s)
- K Kamiya
- Japan Atomic Energy Agency, JAEA, Naka, Ibaraki-ken, 311-0193, Japan
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8
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Shats MG, Xia H, Punzmann H. Spectral condensation of turbulence in plasmas and fluids and its role in low-to-high phase transitions in toroidal plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 71:046409. [PMID: 15903796 DOI: 10.1103/physreve.71.046409] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Indexed: 05/02/2023]
Abstract
Transitions from turbulence to order are studied experimentally in thin fluid layers and in magnetically confined toroidal plasma. It is shown that turbulence self-organizes through the mechanism of spectral condensation in both systems. The spectral redistribution of the turbulent energy leads to the reduction in the turbulence level, generation of coherent flow, reduction in the particle diffusion, and increase in the system's energy. The higher-order state in the plasma is sustained via the non-local spectral coupling of the linearly unstable spectral range to the large-scale mean flow. Spectral condensation of turbulence is discussed in terms of its role in the low-to-high confinement transitions in toroidal plasma which show similarity with phase transitions.
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Affiliation(s)
- M G Shats
- Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia
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9
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Beyer P, Benkadda S, Fuhr-Chaudier G, Garbet X, Ghendrih P, Sarazin Y. Nonlinear dynamics of transport barrier relaxations in tokamak edge plasmas. PHYSICAL REVIEW LETTERS 2005; 94:105001. [PMID: 15783490 DOI: 10.1103/physrevlett.94.105001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Indexed: 05/24/2023]
Abstract
A new mechanism for intermittent relaxations of transport barriers is found by using three dimensional fluid turbulence simulations. This mechanism is generic since it only requires a stationary E x B shear flow. It is found here that if the flow shear increases faster than linearly with heating power, the relaxation frequency decreases with power. An analytical study reveals that this nonlinear dynamics is governed by a time delay for effective velocity shear stabilization.
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Affiliation(s)
- P Beyer
- Equipe Dynamique des Systèmes Complexes, LPIIM, CNRS-Université de Provence, Centre de St. Jérôme, Case 321, 13397 Marseille Cedex 20, France
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10
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Punzmann H, Shats MG. Formation and structure of transport barriers during confinement transitions in toroidal plasma. PHYSICAL REVIEW LETTERS 2004; 93:125003. [PMID: 15447271 DOI: 10.1103/physrevlett.93.125003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2003] [Indexed: 05/24/2023]
Abstract
Density pedestal formation is studied experimentally during spontaneous low-to-high confinement transitions in the H-1 heliac. Poloidally extended potential structures, or zonal flows, seem to play the major role both in the spatial structure and in the temporal evolution of the pedestal formation. Zonal flows transiently generate radially localized maxima in the radial electric-field shear in L mode which coincides with the radial location of the pedestal in H mode.
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Affiliation(s)
- H Punzmann
- Plasma Research Laboratory, Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT 0200, Australia.
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Shats MG, Xia H, Punzmann H, Solomon WM. Spectral Energy Transfer, Generation of Zonal Flows and Their Role in Confinement Transitions. FUSION SCIENCE AND TECHNOLOGY 2004. [DOI: 10.13182/fst04-a566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Michael G. Shats
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200, Australia
| | - Hua Xia
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200, Australia
| | - Horst Punzmann
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200, Australia
| | - Wayne M. Solomon
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200, Australia
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12
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Kim EJ, Diamond PH. Zonal flows and transient dynamics of the L-H transition. PHYSICAL REVIEW LETTERS 2003; 90:185006. [PMID: 12786016 DOI: 10.1103/physrevlett.90.185006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2003] [Indexed: 05/24/2023]
Abstract
We elucidate the role of zonal flows in transient phenomena observed during L-H transition by studying a simple L-H transition model which contains the evolution of zonal flows, mean ExB flows, and the ion pressure gradient. Zonal flows are shown to trigger the L-H transition and cause time-transient behavior through the self-regulation of turbulence before a mean shearing, due to a steep pressure profile, secures a quiescent H mode. Surprisingly, this self-regulation lowers the power threshold for the ultimate transition to a quiescent H-mode state.
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Affiliation(s)
- Eun-jin Kim
- Department of Physics, University of California-San Diego, La Jolla, California 92093-0319, USA
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