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Wang Z, Dai Z, Wang S. Nonlinear excitation of zonal flows by turbulent energy flux. Phys Rev E 2022; 106:035205. [PMID: 36266869 DOI: 10.1103/physreve.106.035205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 08/19/2022] [Indexed: 06/16/2023]
Abstract
The nonlinear excitation of zonal flows (ZFs) generated by the ion-temperature-gradient turbulence in a tokamak plasma is investigated by using the global gyrokinetic code nlt. It is found that ZFs are initially driven by the nonlinear self-interaction of the eigenmode. In the nonlinear saturation, the modulational instability becomes important, and its contribution to ZFs can finally be comparable to that of the self-interaction mechanism. More importantly, both types of nonlinear wave-wave interactions can be well described by the turbulent energy flux model.
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Affiliation(s)
- Zihao Wang
- Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei 230026, China
| | - Zongliang Dai
- Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei 230026, China
| | - Shaojie Wang
- Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei 230026, China
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2
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Kakati B, Pradhan S, Dhongde J, Semwal P, Yohan K, Banaudha M. Edge transport and fluctuation induced turbulence characteristics in early SST-1 plasma. FUSION ENGINEERING AND DESIGN 2017. [DOI: 10.1016/j.fusengdes.2016.12.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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3
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Xu GS, Wan BN, Wang HQ, Guo HY, Zhao HL, Liu AD, Naulin V, Diamond PH, Tynan GR, Xu M, Chen R, Jiang M, Liu P, Yan N, Zhang W, Wang L, Liu SC, Ding SY. First evidence of the role of zonal flows for the L-H transition at marginal input power in the EAST tokamak. PHYSICAL REVIEW LETTERS 2011; 107:125001. [PMID: 22026773 DOI: 10.1103/physrevlett.107.125001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Indexed: 05/31/2023]
Abstract
A quasiperiodic Er oscillation at a frequency of <4 kHz, much lower than the geodesic-acoustic-mode frequency, with a modulation in edge turbulence preceding and following the low-to-high (L-H) confinement mode transition, has been observed for the first time in the EAST tokamak, using two toroidally separated reciprocating probes. Just prior to the L-H transition, the Er oscillation often evolves into intermittent negative Er spikes. The low-frequency Er oscillation, as well as the Er spikes, is strongly correlated with the turbulence-driven Reynolds stress, thus providing first evidence of the role of the zonal flows in the L-H transition at marginal input power. These new findings not only shed light on the underlying physics mechanism for the L-H transition, but also have significant implications for ITER operations close to the L-H transition threshold power.
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Affiliation(s)
- G S Xu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
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4
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Manz P, Ramisch M, Stroth U. Long-range correlations induced by the self-regulation of zonal flows and drift-wave turbulence. Phys Rev E 2011; 82:056403. [PMID: 21230598 DOI: 10.1103/physreve.82.056403] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 10/08/2010] [Indexed: 11/07/2022]
Abstract
By means of a unique probe array, the interaction between zonal flows and broad-band drift-wave turbulence has been investigated experimentally in a magnetized toroidal plasma. Homogeneous potential fluctuations on a magnetic flux surface, previously reported as long range correlations, could be traced back to a predator-prey-like interaction between the turbulence and the zonal flow. At higher frequency the nonlocal transfer of energy to the zonal flow is dominant and the low-frequency oscillations are shown to result from the reduced turbulence activity due to this energy loss. This self-regulation process turns out to be enhanced with increased background shear flows.
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Affiliation(s)
- P Manz
- Center for Energy Research, University of California at San Diego, San Diego, California 92093, USA
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5
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Manz P, Ramisch M, Stroth U. Physical mechanism behind zonal-flow generation in drift-wave turbulence. PHYSICAL REVIEW LETTERS 2009; 103:165004. [PMID: 19905704 DOI: 10.1103/physrevlett.103.165004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Indexed: 05/28/2023]
Abstract
The energetic interaction between drift-wave turbulence and zonal flows is studied experimentally in two-dimensional wave number space. The kinetic energy is found to be transferred nonlocally from the drift waves to the zonal flow. This confirms the theoretical prediction that the parametric-modulational instability is the driving mechanism of zonal flows. The physical mechanism of this nonlocal energetic interaction between and zonal flows and turbulent drift-wave eddies in relation to the suppression of turbulent transport is discussed.
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Affiliation(s)
- P Manz
- Institut für Plasmaforschung, Universität Stuttgart, D-70569 Stuttgart, Germany
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6
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Liu AD, Lan T, Yu CX, Zhao HL, Yan LW, Hong WY, Dong JQ, Zhao KJ, Qian J, Cheng J, Duan XR, Liu Y. Characterizations of low-frequency zonal flow in the edge plasma of the HL-2A tokamak. PHYSICAL REVIEW LETTERS 2009; 103:095002. [PMID: 19792802 DOI: 10.1103/physrevlett.103.095002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2009] [Indexed: 05/28/2023]
Abstract
A low-frequency (<4 kHz), poloidally and toroidally symmetrical potential structure that peaks near zero frequency is observed in the edge plasma of the HL-2A tokamak. The axisymmetry structure exhibits a radial coherence length less than 1 cm. These characteristics are consistent with the theoretically predicted low-frequency zonal flows (LFZF). The radial wave-number frequency spectra of the LFZF show that the LFZF packets propagate both outwards and inwards. The geodesic acoustic mode (GAM) is found to coexist with the LFZF, and the LFZF is found to modulate the GAM and ambient turbulence with in-phase and antiphase relations, respectively, through an envelope analysis.
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Affiliation(s)
- A D Liu
- CAS Key Laboratory of Basic Plasma Physics, and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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7
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Kang JW, Choi YG, Lee JH, Kwon OK, Hwang HJ. Molecular dynamics simulations of carbon nanotube oscillators deformed by encapsulated copper nanowires. MOLECULAR SIMULATION 2008. [DOI: 10.1080/08927020802301953] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Jeong Won Kang
- a Department of Computer Engineering , Chungju National University , Chungju, South Korea
| | - Young Gyu Choi
- a Department of Computer Engineering , Chungju National University , Chungju, South Korea
| | - Jun Ha Lee
- b Department of Computer System Engineering , Sangmyung University , Chonan, South Korea
| | - Oh Kuen Kwon
- c Department of Electronic Engineering , Semyung University , Jecheon, South Korea
| | - Ho Jung Hwang
- d Electrical and Electronic Engineering School, Chung-Ang University , Seoul, South Korea
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8
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Schmitz L, Wang G, Hillesheim JC, Rhodes TL, Peebles WA, White AE, Zeng L, Carter TA, Solomon W. Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:10F113. [PMID: 19044597 DOI: 10.1063/1.2953675] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Doppler backscattering (DBS) has been successfully used to measure the E x B flow velocity and local intermediate wavenumber density fluctuation levels in the DIII-D tokamak. Depending on the launch angle and the frequency of the probing beam, the signal backscattered from the plasma cut-off layer is sensitive to density fluctuations at a specific perpendicular wavenumber (1 < or = k(perpendicular rho(s)) < or = 4). Due to the localization and high time resolution for poloidal flow measurements, DBS is well suited to detect stationary and time-dependent shear flows [zonal flows (ZFs)]. We present a novel scheme to measure ZF spectra using a dual-channel DBS system capable of simultaneously probing two minor radii separated by a distance of 0.2 cm < Delta r < 3 cm. Frequency spectra of geodesic acoustic modes and low frequency ZFs (f or = 10 kHz) have been obtained for 0.6 < r/a < 0.95.
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Affiliation(s)
- L Schmitz
- UCLA Physics and Astronomy Department, Los Angeles, California 90095-1547, USA
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9
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Hamada Y, Watari T, Yamagishi O, Nishizawa A, Narihara K, Kawasumi Y, Ido T, Kojima M, Toi K. Change of zonal flow spectra in the JIPP T-IIU tokamak plasmas. PHYSICAL REVIEW LETTERS 2007; 99:065005. [PMID: 17930839 DOI: 10.1103/physrevlett.99.065005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Revised: 04/09/2007] [Indexed: 05/25/2023]
Abstract
When Ohmically heated low-density plasmas are additionally heated by higher-harmonics ion-cyclotron-range-of frequency heating, heated by neutral beam injection, or strongly gas puffed, the intensity of zonal flows in the geodesic acoustic mode frequency range in the tokamak core plasma decreases sharply and that of low-frequency zonal flow grows drastically. This is accompanied by a damping of the drift wave propagating in the electron diamagnetic drift direction, turbulence by trapped electron mode (TEM), and the increase of the mode propagating to ion diamagnetic drift direction (ITG). In the half-radius region, TEM and high-frequency zonal flows remain intense in both OH and heated phases. ITG and low-frequency zonal flows grow in heated plasmas, suggesting a strong coupling between ITG and low-frequency zonal flow.
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Affiliation(s)
- Y Hamada
- National Institute for Fusion Science, Toki, 509-5292, Japan
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10
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Ryu CM, Rhee T. A Low Frequency Coherent Structure Driven by Turbulence in a Hanbit Mirror Plasma. FUSION SCIENCE AND TECHNOLOGY 2007. [DOI: 10.13182/fst07-a1323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Chang-Mo Ryu
- Department of physics, POSTECH, Pohang 790-784, Korea
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11
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Gupta DK, Fonck RJ, McKee GR, Schlossberg DJ, Shafer MW. Detection of zero-mean-frequency zonal flows in the core of a high-temperature tokamak plasma. PHYSICAL REVIEW LETTERS 2006; 97:125002. [PMID: 17025976 DOI: 10.1103/physrevlett.97.125002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Indexed: 05/12/2023]
Abstract
A low-frequency, spectrally broad (Deltaf approximately 10 kHz) poloidal flow structure that peaks near zero frequency is observed in time-resolved measurements of the turbulence velocity field in the core region (r/a approximately 0.6-0.9) of DIII-D tokamak plasmas. These flows exhibit a long poloidal wavelength (low m) and a short radial coherence length comparable to the ambient turbulence decorrelation length. Characteristics of these observed poloidal flows are consistent with the theoretically predicted residual or zero-mean-frequency zonal flows.
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Affiliation(s)
- D K Gupta
- University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706, USA
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12
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Zhao KJ, Lan T, Dong JQ, Yan LW, Hong WY, Yu CX, Liu AD, Qian J, Cheng J, Yu DL, Yang QW, Ding XT, Liu Y, Pan CH. Toroidal symmetry of the geodesic acoustic mode zonal flow in a tokamak plasma. PHYSICAL REVIEW LETTERS 2006; 96:255004. [PMID: 16907314 DOI: 10.1103/physrevlett.96.255004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 04/28/2006] [Indexed: 05/11/2023]
Abstract
The toroidal symmetry of the geodesic acoustic mode (GAM) zonal flows is identified with toroidally distributed three step Langmuir probes at the edge of the HuanLiuqi-2A (commonly referred to as HL-2A) tokamak plasmas for the first time. High coherence of both the GAM and the ambient turbulence for the toroidally displaced measurements along a magnetic field line is observed, in contrast with the high coherence of the GAM but low coherence of the ambient turbulence when the toroidally displaced measurements are not along the same field line. The radial and poloidal features of the flows are also simultaneously determined. The nonlinear three wave coupling between the high frequency turbulent fluctuations and the flows is demonstrated to be a plausible formation mechanism of the flows.
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Affiliation(s)
- K J Zhao
- Southwestern Institute of Physics, P.O. Box 432, Chengdu, China
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13
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Hamada Y, Watari T, Nishizawa A, Narihara K, Kawasumi Y, Ido T, Kojima M, Toi K. Streamers in the JIPP T-llU tokamak plasmas. PHYSICAL REVIEW LETTERS 2006; 96:115003. [PMID: 16605833 DOI: 10.1103/physrevlett.96.115003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Indexed: 05/08/2023]
Abstract
It is shown that the low-density Ohmically heated tokamak plasmas have streamerlike eddies at the outer region at normalized minor radius of about 0.7 and high-frequency zonal flows of large amplitudes in the core. The amplitudes of the eddies ePhi/kT(e) and n(e)/n(e) are of order of 0.5, similar to that of blobs in the tokamak plasma boundary. The waveforms are featured by pulses of complex shape with sharp fronts, similar to the results of streamer simulations by Garbet et al.. The time constant of the fronts is also in agreement with the simulation. The radial span of the eddies is estimated to be much larger than the poloidal span.
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Affiliation(s)
- Y Hamada
- National Institute for Fusion Science, Toki 509-5292, Japan
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14
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Nagashima Y, Hoshino K, Ejiri A, Shinohara K, Takase Y, Tsuzuki K, Uehara K, Kawashima H, Ogawa H, Ido T, Kusama Y, Miura Y. Observation of nonlinear coupling between small-poloidal wave-number potential fluctuations and turbulent potential fluctuations in Ohmically heated plasmas in the JFT-2M tokamak. PHYSICAL REVIEW LETTERS 2005; 95:095002. [PMID: 16197220 DOI: 10.1103/physrevlett.95.095002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Indexed: 05/04/2023]
Abstract
Two types of electrostatic modes with small-poloidal wave numbers (approximately 1 and 10-15 kHz) are observed in the edge region of Ohmically heated plasmas in the JFT-2M tokamak. The envelope of the higher frequency coherent mode is modulated at the frequency of the lower frequency mode. A bispectral analysis revealed that a significant nonlinear coupling among the two types of fluctuations and the broadband background turbulent potential fluctuations occurs inside the last closed magnetic flux surface, suggesting that a nonlinear process such as the parametric-modulational instability is involved.
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15
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Fujisawa A, Itoh K, Iguchi H, Matsuoka K, Okamura S, Shimizu A, Minami T, Yoshimura Y, Nagaoka K, Takahashi C, Kojima M, Nakano H, Ohsima S, Nishimura S, Isobe M, Suzuki C, Akiyama T, Ida K, Toi K, Itoh SI, Diamond PH. Identification of zonal flows in a toroidal plasma. PHYSICAL REVIEW LETTERS 2004; 93:165002. [PMID: 15524996 DOI: 10.1103/physrevlett.93.165002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Indexed: 05/24/2023]
Abstract
This Letter presents experimental confirmation of the presence of zonal flows in magnetically confined toroidal plasma using an advanced diagnostic system--dual heavy ion beam probes. The simultaneous observation of an electric field at two distant toroidal locations (approximately 1.5 m apart) in the high temperature (approximately 1 keV) plasma provides a fluctuation spectrum of electric field (or flow), a spatiotemporal structure of the zonal flows (characteristic radial length of approximately 1.5 cm and lifetime of approximately 1.5 ms), their long-range correlation with toroidal symmetry (n=0), and the difference in the zonal flow amplitude with and without a transport barrier. These constitute essential elements of turbulence-zonal flow systems, and illustrate one of the fundamental processes of structure formation in nature.
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Affiliation(s)
- A Fujisawa
- National Institute for Fusion Science, Oroshi-cho, Toki-shi, 509-52 Japan
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