Toroidal Symmetry of the Geodesic Acoustic Mode Zonal Flow in a Tokamak Plasma

Zhao, Kun; Lan, Tao; Dong, J. Q.; Yan, L.W.; Hong, W.Y.; Yu, Cong; Liu, A. D.; Qian, J.; Cheng, J.; Yu, D.L.; Yang, Qingwei; Ding, X.T.; Liu, Y.; Pan, C.H.

doi:10.1103/physrevlett.96.255004

Cited by 184 publications

(186 citation statements)

References 25 publications

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“…The other multi-channel array Langmuir probes in H1 [7] and JFT-2M [22] also show the poloidal symmetric structure of the mode (m=0). Recently, in the Chinese device, HL-2A, the complete symmetric characteristics of m=n=0 have been confirmed using probe measurements in the edge of Ohmic discharges [23].…”

Section: -3 Gamsmentioning

confidence: 88%

Experimental progress on zonal flow physics in toroidal plasmas

et al. 2007

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Section: -3 Gamsmentioning

confidence: 88%

Experimental progress on zonal flow physics in toroidal plasmas

et al. 2007

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“…Oscillatory zonal flows, also called geodesic acoustic modes (GAMs) are shown to exist in a high safety factor region of tokamak plasmas [8]. The geodesic acoustic mode (GAM) zonal flows is also identified in HL-2A tokamak plasmas, where high coherence of both the GAM and the ambient turbulence for the toroidally displaced measurements along a magnetic field line is observed [9]. Similarly, JFT-2M tokamak reported the higher frequency fluctuations as geodesic acoustic modes (GAMs) zonal flows [10].…”

Section: Introductionmentioning

confidence: 92%

Coherent structures in electrostatic interchange mode turbulence

Shaikh¹

2006

Phys. Scr.

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Exact nonlinear coherent vortex solutions, in the form of dipolar like configuration, are derived in a two dimensional electrostatic interchange turbulence model. The vortex structure incorporates effects due to nonlinear diamagnetic interactions that are associated with finite Larmour radius of the magnetized ions. Numerical simulations indicate that propagating dipole vortex is a long-lived, spatially well localized coherent structure of the interchange mode that persists for several eddy turn-over time. Collisional as well as weak diamagnetic interactions have stabilizing effects on these structures.

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“…To calculate ⟨ ⟩ ∥ v , we use equation (3) and assume that the transverse energy is conserved (due to the conservation of the magnetic moment). Then…”

Section: Motion and Change Of The Energy Of Resonant Ions In The Gam mentioning

confidence: 99%

“…The mode considered in [7] was purely electrostatic. Like in [1][2][3], it had poloidally symmetric (the poloidal mode number m = 0) scalar potential of the perturbed electric field and asymmetric (m = 1) perturbed particle density. Bursts of the E-GAM instability driven by counter-injected energetic ions resulted in large (10-15%) drops of the neutron emission.…”

mentioning

confidence: 99%

Manifestations of the geodesic acoustic mode driven by energetic ions in tokamaks

Kolesnichenko

Lutsenko

Yakovenko

et al. 2016

Plasma Phys. Control. Fusion

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Effects of the energetic-ion-driven Geodesic Acoustic modes (GAM and E-GAM) on the toroidally passing energetic ions and the concomitant change of the neutron yield of beam-plasma fusion reactions in tokamaks are considered. It is shown that due to large perturbations of the plasma density, the resonant energetic ions driving the instability can be considerably slowed down for a few tens of the particle transit periods, which is much less than the collisional slowing down time. The time of the collisionless slowing down is actually determined by the period of the particle motion within the resonance island arising because of the GAM / E-GAM. Being trapped in the island, the resonant particles can not only lose their energy but also gain it. One more effect of GAMs is the flattening on the distribution function of the resonant particles. Due to conservation of the canonical angular momentum during a GAM / E-GAM instability, the change of the particle energy is accompanied by a radial displacement of the resonant particle for a distance up to the poloidal Larmor radius of energetic ions. The particles are displaced inwards or outwards, depending on the direction of their motion along the magnetic field. Expressions describing the change of the neutron yield due to GAM modes are derived. It is found that the distortion of the velocity distribution of the resonant particles can lead to a considerable drop of the neutron emission even when effects of the particle radial displacement are small. The developed theory is applied to an E-GAM experiment on the DIII-D tokamak. Relations for the period of the motion within the resonance island of passing (both well passing and marginally passing) particles and the width of the resonance of the energetic particles with GAM modes and low-frequency Alfvén modes are derived.

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Toroidal Symmetry of the Geodesic Acoustic Mode Zonal Flow in a Tokamak Plasma

Cited by 184 publications

References 25 publications

Experimental progress on zonal flow physics in toroidal plasmas

Experimental progress on zonal flow physics in toroidal plasmas

Coherent structures in electrostatic interchange mode turbulence

Manifestations of the geodesic acoustic mode driven by energetic ions in tokamaks

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