Recent progress of Alfvén eigenmode experiments using N-NB in JT-60U tokamak

Shinohara, K.; Takechi, M.; Ishikawa, Masatoshi; Kusama, Y.; Morioka, A.; Oyama, N.; Tobita, K.; Ozeki, T.; Team, the JT-60; Gorelenkov, N. N.; Cheng, C. Z.; Kramer, G. J.; Nazikian, R.

doi:10.1088/0029-5515/42/8/302

Cited by 60 publications

(63 citation statements)

References 25 publications

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“…1) plasmas heated with negative ion based neutral beam (NNB) injection. [2][3][4][5] Frequencies of the three instabilities are in the range of shear Alfvén eigenmodes. Frequency sweeping of slow FS mode has a good correlation with equilibrium parameter evolution with time scale Ӎ200 ms. On the other hand, time scales of the fast FS mode and the ALE are, respectively 1 -5 ms and 200-400 s, much shorter than the equilibrium time scale.…”

Section: Introductionmentioning

confidence: 99%

Nonlocal energetic particle mode in a JT-60U plasma

Todo

Shinohara²,

Takechi³

et al. 2004

Physics of Plasmas

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Energetic-ion driven instability in a Japan Atomic Energy Research Institute Tokamak-60 Upgrade (JT-60U) [S. Ishida et al., Phys. Plasmas 11, 2532(2004] plasma was investigated using a simulation code for magnetohydrodynamics and energetic particles. The spatial profile of the unstable mode peaks near the plasma center where the safety factor profile is flat. The unstable mode is not a toroidal Alfvén eigenmode (TAE) because the spatial profile deviates from the expected location of TAE and the spatial profile consists of a single primary harmonic m / n =2/1 where m and n are poloidal and toroidal mode numbers. The real frequency of the unstable mode is close to the experimental starting frequency of the fast frequency sweeping mode. Simulation results demonstrate that energetic-ion orbit width and energetic-ion pressure significantly broaden radial profile of the unstable mode. For the smallest value among the investigated energetic-ion orbit width, the unstable mode is localized within 20% of the minor radius. This gives an upper limit of the spatial profile width of the unstable mode which the magnetohydrodynamic effects alone can induce. For the experimental condition of the JT-60U plasma, energetic ions broaden the radial width of the unstable mode spatial profile by a factor of 3. The unstable mode is primarily induced by the energetic particles.

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Section: Introductionmentioning

confidence: 99%

Nonlocal energetic particle mode in a JT-60U plasma

Todo

Shinohara²,

Takechi³

et al. 2004

Physics of Plasmas

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“…Further experiments and more theoretical modeling is required to understand the alpha-particle redistribution in detail. Since these experiments on TFTR, strong radial redistribution of energetic beam ions has also been observed during negative-ion neutral beam experiments on JT-60U [69][70].…”

Section: Alpha-particle Effect On Mhd Behaviormentioning

confidence: 92%

Review of D-T Experiments Relevant to Burning Plasma Issues

Hawryluk¹

2001

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Progress in the performance of tokamak devices has enabled not only the production of significant bursts of fusion energy from deuterium-tritium (D-T) plasmas in the Tokamak Fusion Test Reactor (TFTR) and the Joint European Torus (JET) but, more importantly, the initial study of the physics of burning magnetically confined plasmas. TFTR and JET, in conjunction with the worldwide fusion effort, have studied a broad range of topics including magnetohydrodynamic stability, transport, wave-particle interactions, the confinement of energetic particles, and plasma boundary interactions. D-T experiments differ in three principal ways from previous experiments: isotope effects associated with the use of deuterium-tritium fuel, the presence of fusion-generated alpha particles, and technology issues associated with tritium handling and increased activation. The effect of deuteriumtritium fuel and the presence of alpha particles is reviewed and placed in the perspective of the much larger worldwide database using deuterium fuel and theoretical understanding.Both devices have contributed substantially to addressing the scientific and technical issues associated with burning plasmas. However, future burning plasma experiments will operate with larger ratios of alpha heating power to auxiliary power and will be able to access additional alpha-particle physics issues. The scientific opportunities for extending our understanding of burning plasmas beyond that provided by current experiments is described.

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“…In most Alfvén eigenmode experiments using NNB injection, bursting instabilities are observed in the frequency range of Alfvén eigenmodes [17,18,21]. One example is shown in Fig.…”

Section: Bursting Instability In the Alfvén Eigenmode Frequency Rangementioning

confidence: 99%

“…(RSAE) [11][12][13] or Alfvén Cascade [14,15]. However, some frequency sweepings has a very short time scale, which cannot be explained by the temporal behavior of the bulk plasma and equilibrium, and are sometime called "frequency chirping modes" [16][17][18]. The instabilities of this type appear as bursts, namely each mode has a short duration, typically less than a few milli-second.…”

Section: Introductionmentioning

confidence: 99%