Zonal flow generation and toroidal Alfvén eigenmode excitation due to tearing mode induced energetic particle redistribution

Abstract Generation of the n = 0 zonal flow and excitation of the n = 1 toroidal Alfvén eigenmode (TAE) due to the redistribution of energetic particles (EPs) by the m/n = 2/1 tearing mode (TM) are systematically studied with the hybrid drift-kinetic magnetohydrodynamic (MHD) simulations (m and n represent the poloidal and toroidal mode number, respectively). In the presence of the m/n = 2/1 TM, the amplitude of the n = 1 TAE shows a slower decay after its first saturation due to the wave-particle nonlinearity and the nonlinear generation of the n = 0 & higher-n (n ≥ 2) sidebands. Meanwhile, a strong n = 0 zonal flow component is nonlinearly generated when both TAE and TM grow to large amplitudes. The redistribution of EPs by the m/n = 2/1 magnetic island results in a continuous drive on the background plasma, and finally produces the zonal flow through the MHD nonlinearity. In addition, the large m/n = 2/1 magnetic island is found to be responsible for the formation of the strong spatial gradient of the EP distribution through the resonance between EPs and TM, which can lead to burst of unstable TAE and destabilization of originally stable TAE.

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Magnetic island suppression by electron cyclotron current drive as converse of a forced reconnection problem

Journal of Plasma Physics ◽

10.1017/s0022377818000569 ◽

2018 ◽

Vol 84 (3) ◽

Cited By ~ 6

Author(s):

D. Grasso ◽

D. Borgogno ◽

L. Comisso ◽

E. Lazzaro

Keyword(s):

Robust Control ◽

Control Strategy ◽

Electron Cyclotron ◽

Current Drive ◽

Magnetic Islands ◽

Tearing Mode ◽

Magnetic Island ◽

Technical Approach ◽

Physical Conditions ◽

Secondary Instabilities

This paper addresses one aspect of the problem of the suppression of tearing mode magnetic islands by electron cyclotron current drive (ECCD) injection, formulating the problem as the converse of a forced reconnection problem. New physical conditions are discussed which should be considered in the technical approach towards a robust control strategy. Limits on the ECCD deposition are determined to avoid driving the system into regimes where secondary instabilities develop. Numerical simulations confirming the theory are also presented.

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Experimental Evidence of Nonlinear Spectral Power Transfer In Zonal Flow Generation

10.1063/1.1593884 ◽

2003 ◽

Author(s):

H. Xia

Keyword(s):

Experimental Evidence ◽

Spectral Power ◽

Zonal Flow ◽

Power Transfer ◽

Flow Generation

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Characterization of zonal flow generation in weak electrostatic turbulence

Physica Scripta ◽

10.1088/0031-8949/77/05/055502 ◽

2008 ◽

Vol 77 (5) ◽

pp. 055502 ◽

Cited By ~ 4

Author(s):

M Negrea ◽

I Petrisor ◽

B Weyssow

Keyword(s):

Zonal Flow ◽

Flow Generation

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Heat Transportation by an Oscillatory Flow Through a Parallel-Plate Channel With an Inserted Slanting Plate

ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference, Volume 1 ◽

10.1115/ht2007-32561 ◽

2007 ◽

Cited By ~ 1

Author(s):

Yoshihisa Ishii ◽

Xiaojin Zhang ◽

Makoto Hishida

Keyword(s):

Parallel Plate ◽

Oscillatory Flow ◽

Electronic Devices ◽

Tidal Amplitude ◽

Womersley Number ◽

Flow Component ◽

Directional Flow ◽

Transportation Channel ◽

Flow Through ◽

Plate Channel

Heat transportation devices with small size and high transportation rate are highly required for achieving effective cooling of electronic devices and equipments. Heat transportation devices exploiting reciprocal flow are considered as one of important candidate technologies. Since a heat transportation pipe exploiting reciprocal flow was invented by Kurzweg and Zhao[1], many researchers have attempted to improve its performance. In the present paper we proposed a new concept of heat transportation channel which was a parallel-plate channel with a slanting plate inserted. The slanting plate separated the parallel-plate channel into two tapered channels. We analyzed numerically the heat transportation performance of the channel when a reciprocal flow was given at one end of the channel. Womersley number Wo was varied in a range of 7≤ Wo ≤40 and Remax in a range of 100≤ Remax ≤1300, by changing the tidal amplitude Am of the reciprocal flow from 0.005 to 0.102 m and reciprocal frequency from 0.07 to 2.56Hz. The present study was summarized in the followings: (1) In the present channel, oscillatory flow comprised of a reciprocal flow component superimposed on a one-directional flow component was induced. (2) u-velocity profiles in pushing phase and in pulling phase were not symmetrical when Wo was relatively small or Remax was large. They approached symmetrical profile in large Wo range and in small Remax range. (3) The time-averaged flow rate V remained almost constant in the Wo range from 7 to 20. They decreased with increasing Wo beyond 20. It also decreased with decreasing Remax. (4) Heat transportation rate Q and heat transportation efficiency η decreased with increasing Wo and decreasing Remax. (5) Work rate W increased with increasing Wo and Remax. (6) The present heat transportation channel was able to transport about 5 to 13 times the heat with 1.4 to 4 times the efficiency by only inserting a slanting plate in a hollow parallel-plate channel.

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