Alpha particle-driven toroidal Alfvén eigenmodes in Tokamak Fusion Test Reactor deuterium–tritium plasmas: Theory and experiments

Fu, G. Y.; Nazikian, R.; Budny, R.; Chang, Z.

doi:10.1063/1.873165

Cited by 23 publications

(20 citation statements)

References 34 publications

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“…The simulation code for investigating an interaction between MHD and energetic particles, MEGA, was extended with the ion Larmar radius effect, and was applied to calculate the linear growth rate and the damping rate of the n = 4 toroidal Alfvén eigenmode (TAE) in the TFTR D-T plasma [28]. The obtained results are consistent with the calculation of the NOVA-K code [29]. Recently, the extended MEGA code has been applied to investigate the non-linear evolution of TAE in an ITER-like plasma [28].…”

Section: Simulation Science Projectsupporting

confidence: 75%

Recent Fusion Research in the National Institute for Fusion Science

Komori

Sakakibara

Sagara

et al. 2011

Plasma and Fusion Research

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The National Institute for Fusion Science (NIFS), which was established in 1989, promotes academic approaches toward the exploration of fusion science for steady-state helical reactor and realizes the establishment of a comprehensive understanding of toroidal plasmas as an inter-university research organization and a key center of worldwide fusion research. The Large Helical Device (LHD) Project, the Numerical Simulation Science Project, and the Fusion Engineering Project are organized for early realization of net current free fusion reactor, and their recent activities are described in this paper. The LHD has been producing high-performance plasmas comparable to those of large tokamaks, and several new findings with regard to plasma physics have been obtained. The numerical simulation science project contributes understanding and systemization of the physical mechanisms of plasma confinement in fusion plasmas and explores complexity science of a plasma for realization of the numerical test reactor. In the fusion engineering project, the design of the helical fusion reactor has progressed based on the development of superconducting coils, the blanket, fusion materials and tritium handling.

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Section: Simulation Science Projectsupporting

confidence: 75%

Recent Fusion Research in the National Institute for Fusion Science

Komori

Sakakibara

Sagara

et al. 2011

Plasma and Fusion Research

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“…10͒ and calculated in the NOVA-K code 8ϫ10 Ϫ3 . 13 The discrepancy might be due to the simplified flux surfaces used here, which are idealized to be concentric. For this benchmark case and for the TAE burst simulation, which is reported in the next section, a standard ''full-f'' method is employed.…”

Section: ͑3͒mentioning

confidence: 99%

Simulation of intermittent beam ion loss in a Tokamak Fusion Test Reactor experiment

2003

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Recurrent bursts of toroidicity-induced Alfvén eigenmodes ͑TAE͒ are studied using a self-consistent simulation model. Bursts of beam ion losses observed in the neutral beam injection experiment at the Tokamak Fusion Test Reactor ͓K. L. Wong et al., Phys. Rev. Lett. 66, 1874 ͑1991͔͒ are reproduced using experimental parameters. It is found that synchronized TAE bursts take place at regular time intervals of 2.9 ms, which is close to the experimental value of 2.2 ms. The stored beam energy saturates at about 40% of that of the classical slowing down distribution. The stored beam energy drop associated with each burst has a modulation depth of 10%, which is also close to the inferred experimental value of 7%. Surface of section plots demonstrate that both the resonance overlap of different eigenmodes and the disappearance of KAM surfaces in phase space due to overlap of higher-order islands created by a single eigenmode lead to particle loss. Only co-injected beam ions build up to a significant stored energy even though their distribution is flattened in the plasma center. However, they are not directly lost, as their orbits extend beyond the outer plasma edge when the core plasma leans on a high field side limiter. The saturation amplitude is ␦B/B ϳ2ϫ10 Ϫ2 , which is larger than would appear to be compatible with experiment. Physical arguments are presented for why the stored energetic particle response observed in the simulation is still plausible.

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“…Parameters that relate to instabilities driven by fast ions are compiled for these discharges in table 1. More detailed TFTR studies of the tritium beam ions [5,6] and of the alpha particles [7][8][9][10] appeared subsequently. Recent JET contributions include new diagnostic techniques related to alpha particles and tritons [11][12][13][14][15].…”

Section: Sources Of Energetic Ionsmentioning

confidence: 99%

Chapter 5: Physics of energetic ions

et al. 2007

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This chapter reviews the progress accomplished since the redaction of the first ITER Physics Basis Nucl. Fusion 39 2137 in the field of energetic ion physics and its possible impact on burning plasma regimes. New schemes to create energetic ions simulating the fusion-produced alphas are introduced, accessing experimental conditions of direct relevance for burning plasmas, in terms of the Alfvénic Mach number and of the normalised pressure gradient of the energetic ions, though orbit characteristics and size cannot always match those of ITER. Based on the experimental and theoretical knowledge of the effects of the toroidal magnetic field ripple on direct fast ion losses, ferritic inserts in ITER are expected to provide a significant reduction of ripple alpha losses in reversed shear configurations. The nonlinear fast ion interaction with kink and tearing modes is qualitatively understood, but quantitative predictions are missing, particularly for the stabilisation of sawteeth by fast particles that can trigger neoclassical tearing modes. A large database on the linear stability properties of the modes interacting with energetic ions, such as the Alfvén eigenmode has been constructed. Comparisons between theoretical predictions and experimental measurements of mode structures and drive/damping rates approach a satisfactory degree of consistency, though systematic measurements and theory comparisons of damping and drive of intermediate and high mode numbers, the most relevant for ITER, still need to be performed. The nonlinear behaviour of Alfvén eigenmodes close to marginal stability is well characterized theoretically and experimentally, which gives the opportunity to extract some information on the particle phase space distribution from the measured instability spectral features. Much less data exists for strongly unstable scenarios, characterised by nonlinear dynamical processes leading to energetic ion redistribution and losses, and identified in nonlinear numerical simulations of Alfvén eigenmodes and energetic particle modes. Comparisons with theoretical and numerical analyses are needed to assess the potential implications of these regimes on burning plasma scenarios, including in the presence of a large number of modes simultaneously driven unstable by the fast ions.

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Alpha particle-driven toroidal Alfvén eigenmodes in Tokamak Fusion Test Reactor deuterium–tritium plasmas: Theory and experiments

Abstract: The toroidal Alfven eigenmodes TAE in the Tokamak Test Fusion Reactor

Cited by 23 publications

References 34 publications

Recent Fusion Research in the National Institute for Fusion Science

Recent Fusion Research in the National Institute for Fusion Science

Simulation of intermittent beam ion loss in a Tokamak Fusion Test Reactor experiment

Chapter 5: Physics of energetic ions

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