Excitation of Internal Kink Modes by Trapped Energetic Beam Ions

Chen, Liu; White, R. B.; Rosenbluth, M. N.

doi:10.1103/physrevlett.52.1122

Cited by 516 publications

(694 citation statements)

References 11 publications

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“…Wave particle interactions can be harmful in that they can induce loss of energetic ions [1,2] or beneficial in that they "channel" energy from the fast ion population to the thermal ion population [3] (rather than the thermal electrons). waves (CAE) [9].…”

Section: Interactions Of Fast Ion Tails With Magnetohydrodynamic (Mhdmentioning

confidence: 99%

Observation of Compressional Alfvén Modes During Neutral-Beam Heating on the National Spherical Torus Experiment

et al. 2001

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Section: Interactions Of Fast Ion Tails With Magnetohydrodynamic (Mhdmentioning

confidence: 99%

Observation of Compressional Alfvén Modes During Neutral-Beam Heating on the National Spherical Torus Experiment

et al. 2001

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“…In the lowest frequency range ͓0 to 120 kHz in Fig. 1͑b͔͒ are energetic particle modes, EPM [3][4][5][6] shown in magenta. These are modes with relatively strong drive and damping; which means that the mode frequency is governed primarily by the interaction of the mode with the fast ion population, i.e., the mode has the frequency that optimizes energy transfer from the fast ions to the mode.…”

Section: Physics Of Plasmas 13 056109 ͑2006͒mentioning

confidence: 99%

Collective fast ion instability-induced losses in National Spherical Tokamak Experiment

et al. 2006

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A wide variety of fast ion driven instabilities are excited during neutral beam injection ͑NBI͒ in the National Spherical Torus Experiment ͑NSTX͒ ͓Nucl. Fusion 40, 557 ͑2000͔͒ due to the large ratio of fast ion velocity to Alfvén velocity, V fast / V Alfvén , and high fast ion beta. The ratio V fast / V Alfvén in ITER ͓Nucl. Fusion 39, 2137 ͑1999͔͒ and NSTX is comparable. The modes can be divided into three categories: chirping energetic particle modes ͑EPM͒ in the frequency range 0 to 120 kHz, the toroidal Alfvén eigenmodes ͑TAE͒ with a frequency range of 50 kHz to 200 kHz, and the compressional and global Alfvén eigenmodes ͑CAE and GAE, respectively͒ between 300 kHz and the ion cyclotron frequency. Fast ion driven modes are of particular interest because of their potential to cause substantial fast ion losses. In all regimes of NBI heated operation we see transient neutron rate drops, correlated with bursts of TAE or fishbone-like EPMs. The fast ion loss events are predominantly correlated with the EPMs, although losses are also seen with bursts of multiple, large amplitude TAE. The latter is of particular significance for ITER; the transport of fast ions from the expected resonance overlap in phase space of a "sea" of large amplitude TAE is the kind of physics expected in ITER. The internal structure and amplitude of the TAE and EPMs has been measured with quadrature reflectometry and soft x-ray cameras. The TAE bursts have internal amplitudes of ñ / n = 1% and toroidal mode numbers 2 Ͻ n Ͻ 7. The EPMs are core localized, kink-like modes similar to the fishbones in conventional aspect ratio tokamaks. Unlike the fishbones, the EPMs can be present with q͑0͒ Ͼ 1 and can have a toroidal mode number n Ͼ 1. The range of the frequency chirp can be quite large and the resonance can be through a fishbone-like precessional drift resonance, or through a bounce resonance.

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“…The possible detrimental effects of collective shear Allven (s.A.) fluctuations [10,II] as well as of lower frequency MHD modes [12,13,14] on energetic ion confinement properties were recognized in the early years of fusion research and ever since the stabflity properties of AUvenic and MHD fluctuations have been an important subject of the field. Shear AUven waves are of particular relevance for two main reasons: (i) they are nearly incompressible (easier to excite) and (ii) their group velocity is directed along the equilibrium confining B field, so that resonant particles moving paraUel to B can stay in resonance with the s.A. wave-packet.…”

Section: Collective Behaviors and Fast Ion Transportmentioning

confidence: 99%

“…A large variety of Alfvenic oscillations are observed experimentally and there exists an entire "zoology" for their classification based on empirical observations [21]. Here, we want to stress that all these fluctuations can be classified, according to one single unified theoretical framework, as either AUven Eigenmodes (AE) or Energetic Particle Modes (EPM) [6,8,13,22,23,24,25]. In fact, perturbations of the s.A. wave spectrum generally consist of singular (inertial) and regular (ideal MHD) structures.…”

Section: Collective Behaviors and Fast Ion Transportmentioning

confidence: 99%

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Nonlinear Dynamics and Complex Behaviors in Magnetized Plasmas of Fusion Interest

Zonca¹,

Chen²

2008

AIP Conference Proceedings

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Abstract. Complexity and self-organization in burning plasmas are consequence of the interaction of energetic ions with plasma instabilities and turbulence; of the strong nonlinear coupling that will take place between fusion reactivity profiles, pressure driven currents, MHD stability, transport and plasma boundary interactions, mediated by the energetic particle population; and finally of the long time scale nonlinear (complex) behaviors that may affect the overall fusion performance and eventually pose issues for the stability and control of the fusion burn. These issues are briefly discussed in this work, with a view on their potential applications to other research areas.

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Excitation of Internal Kink Modes by Trapped Energetic Beam Ions

Cited by 516 publications

References 11 publications

Observation of Compressional Alfvén Modes During Neutral-Beam Heating on the National Spherical Torus Experiment

Observation of Compressional Alfvén Modes During Neutral-Beam Heating on the National Spherical Torus Experiment

Collective fast ion instability-induced losses in National Spherical Tokamak Experiment

Nonlinear Dynamics and Complex Behaviors in Magnetized Plasmas of Fusion Interest

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