Experimental investigation of the radial structure of energetic particle driven modes

Horváth, L.; Papp, G.; Lauber, P.; Por, G.; Gude, A.; Igochine, V.; Geiger, B.; Maraschek, M.; Guimarãis, L.; Nikolaeva, V.; Pokol, Gergö

doi:10.1088/0029-5515/56/11/112003

Cited by 30 publications

(42 citation statements)

References 36 publications

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“…The parallel velocity anisotropies arising from the highly non-thermalised fast ion distribution function may indeed lead to an energy transfer from the energetic ions to the EGAM via inverse Landau damping and to a growth of this mode. The presence of energeticparticle-induced geodesic acoustic modes, excited through external NBI and ICRH heating, has also been observed experimentally in different plasma devices and in different plasma conditions at DIII-D [26], LHD [27] ASDEX Upgrade [28] and JET [11]. Furthermore, Ref.…”

Section: Introductionmentioning

confidence: 69%

“…For different radial positions, the fast ion density decreases and the drive, which is already significantly weak at ρ pol = 0.5 barely overcomes the thermal damping and the mode is strongly weakened. However, for a more realistic comparison with the experimental measurements of the EGAM radial structure [28] -measured at ρ pol ∼ 0.3 -, a more accurate description of the fast ion background distribution function and of the nonlinear physics needs to be considered.…”

Section: A Flat Density and Temperature Profilesmentioning

confidence: 99%

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Effect of elongation on energetic particle-induced geodesic acoustic mode

et al. 2018

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The effect of the plasma elongation on the energetic-particle-induced geodesic acoustic mode (EGAM) dynamics is studied with numerical simulations performed with the gyrokinetic codes GENE and ORB5 and assessed with analytical models. The former code has been recently extended to support non-Maxwellian distribution functions and for the first time global results are shown here and benchmarked against the code ORB5. Taking advantage of these recent developments in GENE, which allow a joint investigation with ORB5, linear electrostatic simulations with adiabatic electrons have been performed. The impact of the elongation on the EGAM dynamics and excitation mechanism is investigated through the study of the energy exchange terms between the particle and the mode for different plasma geometry. Finally, the results are applied to the study of an AS-DEX Upgrade discharge with strongly elongated plasma employing realistic density and temperature profiles.

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Section: Introductionmentioning

confidence: 69%

Section: A Flat Density and Temperature Profilesmentioning

confidence: 99%

Effect of elongation on energetic particle-induced geodesic acoustic mode

et al. 2018

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“…The AUG shot #31213 at time 0.84 s has been selected within the Non-Linear Energeticparticle Dynamics (NLED) Eurofusion enabling research project 9,46 . It has been chosen to study the effect of the energetic particles (EPs) on the dynamics of EGAMs.…”

Section: Application To Egams In Aug Shot #31213mentioning

confidence: 99%

Implementation of energy transfer technique in ORB5 to study collisionless wave-particle interactions in phase-space

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Biancalani

Bottino

et al. 2021

Computer Physics Communications

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A new diagnostic has been developed to investigate the wave-particle interaction in the phase-space in gyrokinetic particle-in-cell codes. Based on the projection of energy transfer terms onto the velocity space, the technique has been implemented and tested in the global code ORB5 and it gives an opportunity to localise velocity domains of maximum wave-plasma energy exchange for separate species. Moreover, contribution of different species and resonances can be estimated as well, by integrating the energy transfer terms in corresponding velocity domains. This Mode-Plasma-Resonance (MPR) diagnostic has been applied to study the dynamics of the Energetic-particle-induced Geodesic Acoustic Modes (EGAMs) in an ASDEX Upgrade shot, by analysing the influence of different species on the mode time evolution.Since the equations on which the diagnostic is based, are valid in both linear and nonlinear cases, this approach can be applied to study nonlinear plasma effects. As a possible future application, the technique can be used, for instance, to investigate the nonlinear EGAM frequency chirping, or the plasma heating due to the damping of the EGAMs.

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“…The EGAM dynamics is going to be investigated in the plasma configuration of the ASDEX Upgrade (AUG) discharge #31213@0.84 s (referred to as the NLED-AUG case) 24,25 , where a rich EP nonlinear dynamics is present 26 . In this discharge, various types of EP-driven instabilities were identified, among which there are Alfvén instabilities (see, for example, Ref.…”

Section: Introductionmentioning

confidence: 99%

“…FIG. 1: Experimental EGAM spectrum 24,26 in the NLED AUG discharge #31213@0.84 s , obtained from Mirnov coils ( Fig. 1a).…”

Section: Introductionmentioning

confidence: 99%

Nonlinear dynamics of energetic-particle driven geodesic acoustic modes in ASDEX Upgrade

et al. 2020

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Turbulence in tokamaks generates radially sheared zonal flows (ZFs). Their oscillatory counterparts, geodesic acoustic modes (GAMs), appear due to the action of the magnetic field curvature. The GAMs can also be driven unstable by an anisotropic energetic particle (EP) population leading to the formation of global radial structures, called EGAMs. The EGAMs might play the role of an intermediate agent between the EPs and thermal plasma, by redistributing EP energy to the bulk plasma through collisionless wave-particle interaction. In such a way, the EGAMs might contribute to the plasma heating. Thus, investigation of EGAM properties, especially in the velocity space, is necessary for precise understanding of the transport phenomena in tokamak plasmas. In this work, the nonlinear dynamics of EGAMs is investigated with the help of a Mode-Particle-Resonance (MPR) diagnostic recently implemented in the global gyrokinetic (GK) particle-in-cell code ORB5. This enables to investigate the relative importance and the evolution of the resonances responsible for the ion and electron Landau damping, and of the EP drive. An ASDEX Upgrade discharge is chosen as a reference case for this investigation due to its rich EP nonlinear dynamics.

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Experimental investigation of the radial structure of energetic particle driven modes

Cited by 30 publications

References 36 publications

Effect of elongation on energetic particle-induced geodesic acoustic mode

Effect of elongation on energetic particle-induced geodesic acoustic mode

Implementation of energy transfer technique in ORB5 to study collisionless wave-particle interactions in phase-space

Nonlinear dynamics of energetic-particle driven geodesic acoustic modes in ASDEX Upgrade

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