Causal Relationship between Zonal Flow and Turbulence in a Toroidal Plasma

Fujisawa, A.; Shimizu, A.; Nakano, H.; Ohshima, S.; Itoh, K.; Nagashima, Yoshihiko; Itoh, Sanae I.; Iguchi, H.; Yoshimura, Y.; Minami, Takashi; Nagaoka, K.; Takahashi, C.; Kojima, M.; Nishimura, Satoshi; Isobe, M.; Suzuki, C.; Akiyama, Tsuyoshi; Ido, T.; Matsuoka, K.; Okamura, S.; Diamond, P. H.

doi:10.1143/jpsj.76.033501

Cited by 32 publications

(40 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These two kinds of responses of turbulence against zonal flow have been confirmed by experiments [54]. Figure 8 (a) illustrates the evolution of zonal flow electric field and spectrum of high frequency turbulence.…”

Section: E × B Flow and Fluctuationssupporting

confidence: 64%

“…8 (b), the dotted line indicates the 'envelope' of zonal flow intensity, i.e., the longer-time average of zonal flow intensity, where the integration time for average is longer than the period of zonal flow oscillation. The correlation between the longer-time average of zonal flow intensity and turbulence intensity is demonstrated in [54] too. A monotonic dependence of the turbulence intensity on the squared intensity of zonal flows is shown.…”

Section: E × B Flow and Fluctuationsmentioning

confidence: 88%

See 1 more Smart Citation

An Assessment of Limit Cycle Oscillation Dynamics Prior to L-H Transition

Itoh

Fujisawa

2013

Plasma and Fusion Research

Self Cite

View full text Add to dashboard Cite

In this article, experimental observations of limit cycle oscillations (LCO) that precede L-to-H transition are discussed. Issues are: (1) the existence of zonal flows, (2) spatio-temporal evolutions of turbulence intensity, and (3) periodic generations/decays of mean radial electric field and density. The role of Reynolds stress to accelerate the LCO flow is also addressed. The propagation of changes of the density gradient and turbulence amplitude into the core is commented. Varieties in experimental reports on these issues are explained, and possible origins of different interpretations are discussed. Problem definitions for the future research for resolution are presented.

show abstract

Section: E × B Flow and Fluctuationssupporting

confidence: 64%

Section: E × B Flow and Fluctuationsmentioning

confidence: 88%

An Assessment of Limit Cycle Oscillation Dynamics Prior to L-H Transition

Itoh

Fujisawa

2013

Plasma and Fusion Research

Self Cite

View full text Add to dashboard Cite

show abstract

“…On the other hand, the fluctuation neighboring to the zonal flow shows a positive correlation ͑␥ = 0.49͒, and follows the zonal flow concomitantly like a tail as q tail ͑1.5, 10͒ϳ0.63q zonal . Accordingly, the zonal flow power fraction increases as the turbulence power fraction decreases, 25 suggesting that the quasienergy conservation law is valid between stationary zonal flow and turbulence.…”

Section: A Energy Transfer Between Zonal Flows and Turbulencementioning

confidence: 96%

“…The first complete identification of the stationary zonal flow was made in Compact Helical System ͑CHS͒ using twin heavy ion beam probes ͑HIBPs͒, 10 with the observation of coherent modes conjectured as GAMs. 21 Further progress has been made in CHS; for example, to really confirm the presence of the interaction or nonlinear coupling between zonal flow and turbulence 21,[24][25][26] using an advanced data-processing technique-wavelet bicoherence analysis.…”

Section: Introductionmentioning

confidence: 99%

Experimental studies of zonal flow and field in compact helical system plasma

et al. 2008

View full text Add to dashboard Cite

using twin heavy ion beam probes. The paper presents the experimental observations of stationary zonal flow, nonlinear couplings between zonal flow and turbulence, and the role of zonal flow in the improved confinement, together with the recent discovery of zonal magnetic field. The presented experimental results strongly support the new paradigm that the plasma transport should be considered as a system of drift wave and zonal flows, and provides the first direct evidence for turbulence dynamo that the structured magnetic field can be really generated by turbulence.

show abstract

“…ZFs are turbulence-generated, poloidally symmetric, low-frequency potential structures, 1 which can play an important role in turbulence self-regulation. 2 The observation of ZF is ubiquitous in gyrokinetic turbulence simulations. Direct experimental evidence of GAMs and ZFs in toroidal plasmas has been obtained using heavy ion beam probe diagnostics, 3 Langmuir probes, 4,5 and beam emission spectroscopy ͑BES͒.…”

mentioning

confidence: 99%

Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system

Schmitz

Wang

Hillesheim

et al. 2008

Review of Scientific Instruments

View full text Add to dashboard Cite

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.

show abstract

Causal Relationship between Zonal Flow and Turbulence in a Toroidal Plasma

Cited by 32 publications

References 24 publications

An Assessment of Limit Cycle Oscillation Dynamics Prior to L-H Transition

An Assessment of Limit Cycle Oscillation Dynamics Prior to L-H Transition

Experimental studies of zonal flow and field in compact helical system plasma

Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system

Contact Info

Product

Resources

About