Ripple induced fast ion loss and related effects in JT-60U

Tobita, K.; Tani, K.; Kusama, Y.; Nishitani, T.; Ikeda, Yujiro; Neyatani, Y.; Коновалов, С. В.; Kikuchi, M.; Koide, Y.; Hamamatsu, K.; Takeuchi, Hiroshi; Fujii, T.

doi:10.1088/0029-5515/35/12/i20

Cited by 71 publications

(57 citation statements)

References 18 publications

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“…In the full combustion method, the tritium contained in a sample was measured by burning it in air at 1000°C for 6 h, converting unoxidized tritium into HTO on a hot copper bed (CuO) at 500°C. To assess the energetic triton loss from the plasma, the Orbit Following Monte-Carlo (OFMC) code [7,8] was used. Coulomb collisions between the energetic tritons and the plasma were simulated.…”

Section: Methodsmentioning

confidence: 99%

Major results of the cooperative program between JAERI and universities using plasma facing materials in JT-60U

Miya¹,

Tanabe

Nishikawa

et al. 2004

Journal of Nuclear Materials

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Section: Methodsmentioning

confidence: 99%

Major results of the cooperative program between JAERI and universities using plasma facing materials in JT-60U

Miya¹,

Tanabe

Nishikawa

et al. 2004

Journal of Nuclear Materials

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“…In tokamaks, toroidal field ripple can drive high levels of fast particle stochastic ripple loss 32 , particularly in regions of high plasma q and q'. High ripple loss rates in reversed shear for 1 MeV tritons were found in measurements of triton burnup 33 on Japan Atomic Energy Research Institute Tokamak-60 Upgrade (JT-60U) 34 and in predictive simulations for the International Thermonuclear Experimental Reactor (ITER) 35 of 3.5 MeV alpha particles 11,36,37 . Similarly, high values of magnetic field ripple in a QAS reactor may cause unacceptable losses of fast ions.…”

Section: Simulations Of Alpha Particle Transport In a Qas Reactormentioning

confidence: 99%

Energetic particle transport in compact quasi-axisymmetric stellarators

et al. 1999

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Hamiltonian coordinate, guiding center code calculations of the confinement of suprathermal ions in quasi-axisymmetric stellarator (QAS) designs have been carried out to evaluate the atractiveness of compact configurations which are optimized for ballooning stability. A new stellarator particle following code is used to predict ion loss rates and particle confinement for thermal and neutral beam ions in a small experiment with R=145 cm, B= 1-2 T and for alpha particles in a reactor size device. In contrast to tokamaks, it is found that high edge poloidal flux has limited value in improving ion confinement in QAS, since collisional pitch angle scattering drives ions into ripple wells and stochastic field regions, where they are quickly lost. The necessity for reduced stellarator ripple fields is emphasized. The high neutral beam ion loss predicted for these configurations suggests that more interesting physics could be explored with an experiment of less constrained size and magnetic field geometry.PACS numbers 52.20.Dq, 52.55.Hc,52.65.Cc,52.65.-y 2

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“…The resulting heat load on the first wall limits the allowable TF ripple amplitude in a tokamak fusion reactor, thereby setting a lower limit on the number of coils. The major points that were understood on ripple losses at the time of the publication of the ITER Physics Basis were: (1) ripple losses are numerically predictable as indicated by experiments in JET [53], JT-60U [54] and TFTR [10]; (2) ripple losses of α-particles in ITER are anticipated to be negligible in discharges with monotonic, positive magnetic shear [3]; (3) on the other hand, the losses can be a concern in advanced operation scenarios based on reversed shear. Since the writing of the ITER Physics Basis, publications on ripple loss experiments have appeared for TFTR [6,10,55,56], JFT-2M [57][58][59] and Tore Supra [60,61].…”

Section: Ripple-induced Lossesmentioning

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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Ripple induced fast ion loss and related effects in JT-60U

Cited by 71 publications

References 18 publications

Major results of the cooperative program between JAERI and universities using plasma facing materials in JT-60U

Major results of the cooperative program between JAERI and universities using plasma facing materials in JT-60U

Energetic particle transport in compact quasi-axisymmetric stellarators

Chapter 5: Physics of energetic ions

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