CASTOR-K: Stability Analysis of Alfvén Eigenmodes in the Presence of Energetic Ions in Tokamaks

Borba, D.; Kerner, W.

doi:10.1006/jcph.1999.6264

Cited by 48 publications

(68 citation statements)

References 47 publications

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“…If the mode was being destabilized by a population of trapped particles with a temperature around 1 MeV, then one would expect averaged precessional drift frequencies below 50 kHz while the observed MHD activity was in the range of 50-70 kHz. To identify which particles were destabilizing the fishbone branch, the CASTOR-K code 16 was used to calculate the resonant transference of energy between an n =1, m = 1 mode with a frequency of 70 kHz and an on-axis ICRH-driven fast ions population with T HOT = 1 MeV, which is around the value estimated for these discharges. The CASTOR-K used the eigenfunction calculated by the MISHKA code 17 and simulations were carried out for a vast range of conditions.…”

Section: Resonant Ionsmentioning

confidence: 99%

Fishbones in Joint European Torus plasmas with high ion-cyclotron-resonance-heated fast ions energy content

Nabais¹,

Borba²,

Mantsinen³

et al. 2005

Physics of Plasmas

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Section: Resonant Ionsmentioning

confidence: 99%

Fishbones in Joint European Torus plasmas with high ion-cyclotron-resonance-heated fast ions energy content

Nabais¹,

Borba²,

Mantsinen³

et al. 2005

Physics of Plasmas

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“…only the eigenvalue and not the eigenfunction is allowed to change. The most important numerical codes based on this model are CASTOR-K [18] and NOVA-K [15], the extensions of the resistive MHD spectral stability codes CASTOR [26] resp. NOVA.…”

Section: Introductionmentioning

confidence: 99%

LIGKA: A linear gyrokinetic code for the description of background kinetic and fast particle effects on the MHD stability in tokamaks

Lauber

Günter

Könies

et al. 2007

Journal of Computational Physics

119

122

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In a plasma with a population of super-thermal particles generated by heating or fusion processes, kinetic effects can lead to the additional destabilisation of MHD modes or even to additional energetic particle modes. In order to describe these modes, a new linear gyrokinetic MHD code has been developed and tested, LIGKA (linear gyrokinetic shear Alfvén physics) [Ph. Lauber, Linear gyrokinetic description of fast particle effects on the MHD stability in tokamaks, Ph.D. Thesis, TU Mü nchen, 2003; Ph. Lauber, S. Gü nter, S.D. Pinches, Phys. Plasmas 12 (2005) 122501], based on a gyrokinetic model [H. Qin, Gyrokinetic theory and computational methods for electromagnetic perturbations in tokamaks, Ph.D.Thesis, Princeton University, 1998]. A finite Larmor radius expansion together with the construction of some fluid moments and specification to the shear Alfvén regime results in a self-consistent, electromagnetic, non-perturbative model, that allows not only for growing or damped eigenvalues but also for a change in mode-structure of the magnetic perturbation due to the energetic particles and background kinetic effects.Compared to previous implementations [H. Qin, mentioned above], this model is coded in a more general and comprehensive way. LIGKA uses a Fourier decomposition in the poloidal coordinate and a finite element discretisation in the radial direction. Both analytical and numerical equilibria can be treated. Integration over the unperturbed particle orbits is performed with the drift-kinetic HAGIS code [S.D. Pinches, Ph.D. Thesis, The University of Nottingham, 1996; S.D. Pinches et al., CPC 111 (1998) 131] which accurately describes the particles' trajectories. This allows finite-banana-width effects to be implemented in a rigorous way since the linear formulation of the model allows the exchange of the unperturbed orbit integration and the discretisation of the perturbed potentials in the radial direction.Successful benchmarks for toroidal Alfvén eigenmodes (TAEs) and kinetic Alfvén waves (KAWs) with analytical results, ideal MHD codes, drift-kinetic codes and other codes based on kinetic models are reported.

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“…Examples for these modes are the toroidal Alfvén eigenmodes (TAEs) [3], [4]that exist in gaps in the Alfvén continuum due to toroidal coupling, or the Alfvén cascade modes (ACs) [5] that can exist if the q-profile exhibits a local minimum or is very flat. Extensive theoretical and numerical investigations have been carried out concerning their drive [1] [6] and damping [7][8][9] [10]. There are two reasons why the accurate determination of damping rates is particularly difficult: firstly, the damping rates for modes of the very same type can vary over several orders of magnitude depending on the different plasma background conditions, i.e.…”

Section: Introductionmentioning

confidence: 99%

Damping and drive of low-frequency modes in tokamak plasmas

Lauber

Günter

2008

Nucl. Fusion

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Abstract.The ability to predict the stability of fast-particle-driven Alfvén eigenmodes in burning fusion plasmas requires a detailed understanding of the dissipative mechanisms that damp these modes. In order to address this question, the linear gyro-kinetic, electromagnetic code Ligka [11], [12] is employed to investigate their behaviour in realistic tokamak geometry. Recently, the model and the implementation of Ligka were extended in order to capture rigorously the coupling of the shear Alfvén wave to the drift and sound waves. This coupling becomes important for the investigation of low frequency modes like the Alfvén cascade modes (AC), the beta-induced Alfvén eigenmodes (BAE), the geodesic acoustic modes (GAM), the energetic particle modes (EPM) and -at even lower frequencies -the resistive wall modes (RWM). The authors report on an effort to close the gap between high-n micro-scale turbulence codes (in their linear phase) and low-n global MHD codes. More precisely, the aim is to describe both regimes within the same framework of equations and with the same numerical implementation by improving the range of applicability and validity of Ligka: an eigenvalue code allows to explore both the local complex dispersion relations for e.g. kinetic Alfvén waves (electromagnetic), ion acoustic waves (electrostatic) or drift waves in realistic geometry and also the their global eigenfunctions. As an application of this extension, an investigation of the kinetic RWM damping mechanisms is carried out.

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CASTOR-K: Stability Analysis of Alfvén Eigenmodes in the Presence of Energetic Ions in Tokamaks

Cited by 48 publications

References 47 publications

Fishbones in Joint European Torus plasmas with high ion-cyclotron-resonance-heated fast ions energy content

Fishbones in Joint European Torus plasmas with high ion-cyclotron-resonance-heated fast ions energy content

LIGKA: A linear gyrokinetic code for the description of background kinetic and fast particle effects on the MHD stability in tokamaks

Damping and drive of low-frequency modes in tokamak plasmas

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