Effects of complex magnetic ripple on fast ions in JFT-2M ferritic insert experiments

Shinohara, K.; Kawashima, H.; Tsuzuki, K.; Urata, K.; Satō, Masayasu; Ogawa, Hideyuki; Kamiya, K.; Sasao, H.; Kimura, Hiroyuki; Kasai, S.; Kusama, Y.; Miura, Y.; Tobita, K.; Naito, O.; Darrow, D. S.

doi:10.1088/0029-5515/43/7/312

Cited by 54 publications

(62 citation statements)

References 14 publications

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“…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%

“…The two codes provide similar estimates of the α-particle losses in ITER positive shear and reversed shear plasmas [69]. The OFMC code has recently been upgraded to treat a three-dimensional TF ripple distribution and a realistic wall structure (F3D-OFMC) [59]. Nevertheless, the use of the code for calculating the beam-ion losses in present tokamak experiments has been so far very limited.…”

Section: Code Developmentmentioning

confidence: 99%

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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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Section: Ripple-induced Lossesmentioning

confidence: 99%

Section: Code Developmentmentioning

confidence: 99%

Chapter 5: Physics of energetic ions

et al. 2007

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“…Although good agreement between the measured and modelled thermocouple temperature response was found, there were still questions about possible heat-load contributions from the thermal plasma and of the precise shape of the hot spot on the tiles. In those studies four fast-ion transport codes were used, the ASCOT code [6], the DELTA5D Monte Carlo code [7], the OFMC code [8,9] and the SPIRAL code [10]. The codes gave very similar answers for the total power deposited in the TBM hot spots coming from particles deposited near 0029 the plasma edge (r/a > 0.7) [4], but the details on the size, shape, and peak heat loads of the spot were different.…”

Section: Introductionmentioning

confidence: 99%

Simulation of localized fast-ion heat loads in test blanket module simulation experiments on DIII-D

et al. 2013

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Infrared imaging of hot spots induced by localized magnetic perturbations using the test blanket module (TBM) mock-up on DIII-D is in good agreement with beam-ion loss simulations. The hot spots were seen on the carbon protective tiles surrounding the TBM as they reached temperatures over 1000• C. The localization of the hot spots on the protective tiles is in fair agreement with fast-ion loss simulations using a range of codes: ASCOT, SPIRAL and OFMCs while the codes predicted peak heat loads that are within 30% of the measured ones. The orbit calculations take into account the birth profile of the beam ions as well as the scattering and slowing down of the ions as they interact with the localized TBM field. The close agreement between orbit calculations and measurements validate the analysis of beam-ion loss calculations for ITER where ferritic material inside the tritium breeding TBMs is expected to produce localized hot spots on the first wall.

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“…The 3D vacuum magnetic field was calculated by using the FEMAG code [12] to properly include the TBM effect. FEMAG calculates the effect on the total field including the poloidal field due to the plasma current as well as the vacuum field.…”

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Effects of complex symmetry-breakings on alpha particle power loads on first wall structures and equilibrium in ITER

Shinohara¹,

Kurki-Suonio²,

Spong³

et al. 2011

Nucl. Fusion

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Abstract. Within the ITPA Topical Group on Energetic Particles, we have investigated the impact that various mechanisms breaking the tokamak axisymmetry can have on the fusion alpha particle confinement in ITER as well as on the wall power loads due to these alphas. In addition to the well known TF ripple, the 3D effect due to ferromagnetic materials (in ferritic inserts, FI, and test blanket modules, TBM) and ELM mitigation coils are included in these mechanisms. ITER Scenario-4 was chosen since, due to its lower plasma current, it is more vulnerable for various off-normal features. First, the validity of using a 2D equilibrium was investigated: a 3D equilibrium was reconstructed using the VMEC code, and it was verified that no 3D equilibrium reconstruction is needed but it is sufficient to add the vacuum field perturbations onto an axisymmetric equilibrium. Then the alpha particle confinement was studied using three independent codes, ASCOT, DELTA5D, and F3D OFMC, all of which assume MHD quiescent background plasma and no anomalous diffusion. All the codes gave a loss power fraction of about 0.2% . The distribution of the peak power load was found to depend on the first wall shape. We also made the first attempt to accommodate the effect of fast ion related MHD on the wall loads in ITER using the HMGC and ASCOT codes. The power flux to the wall was found to increase due to the redistribution of fast ion by the MHD activity. Furthermore, the effect of the ELM mitigation field on the fast ion confinement was addressed by simulating NBI ions with the F3D OFMC code. The loss power fraction of NBI ions was found to increase from 0.3 % without the ELM mitigation field to 4-5% with the ELM mitigation field.

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Effects of complex magnetic ripple on fast ions in JFT-2M ferritic insert experiments

Cited by 54 publications

References 14 publications

Chapter 5: Physics of energetic ions

Chapter 5: Physics of energetic ions

Simulation of localized fast-ion heat loads in test blanket module simulation experiments on DIII-D

Effects of complex symmetry-breakings on alpha particle power loads on first wall structures and equilibrium in ITER

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