The effect of off-axis neutral beam injection on sawtooth stability in ASDEX Upgrade and Mega-Ampere Spherical Tokamak

Chapman, I. T.; Bock, M. F. De; Pinches, S. D.; Turnyanskiy, M.; Team, Mast; Igochine, V.; Maraschek, M.; Tardini, G.

doi:10.1063/1.3187905

Cited by 22 publications

(31 citation statements)

References 42 publications

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“…This mechanism is described in detail in [9,10]. The effect of passing fast ions has been confirmed in NBI experiments in JET [11,12], ASDEX Upgrade [13] and MAST [14] and using He 3 minority ICRH in JET [15,16]. By employing He 3 minority heating schemes (which are envisaged for ITER ICRF heating), the resultant current drive is negligible [10,17].…”

Section: Introductionmentioning

confidence: 96%

Sawtooth control in ITER using ion cyclotron resonance heating

Chapman

Graves²,

Johnson

et al. 2011

Plasma Phys. Control. Fusion

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Numerical modelling of the effects of ion cyclotron resonance heating (ICRH) on the stability of the internal kink mode suggests that ICRH should be considered as an essential sawtooth control tool in ITER. Sawtooth control using ICRH is achieved by directly affecting the energy of the internal kink mode rather than through modification of the magnetic shear by driving localized currents. Consequently, ICRH can be seen as complementary to the planned electron cyclotron current drive actuator, and indeed will improve the efficacy of current drive schemes. Simulations of the ICRH distribution using independent RF codes give confidence in numerical predictions that the stabilizing influence of the fusion-born alphas can be negated by appropriately tailored minority 3 He ICRH heating in ITER. Finally, the effectiveness of all sawtooth actuators is shown to increase as the q = 1 surface moves towards the manetic axis, whilst the passive stabilization arising from the alpha and NBI particles decreases.

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Section: Introductionmentioning

confidence: 96%

Sawtooth control in ITER using ion cyclotron resonance heating

Chapman

Graves²,

Johnson

et al. 2011

Plasma Phys. Control. Fusion

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“…[45], the outermost beam, with R tan =130 cm, provides substantial off-axis neutral beam current drive (NBCD). Note that off-axis NBCD has been observed in conventional aspect ratio tokamaks [50][51][52][53][54], as well as STs [55].…”

Section: : the Nstx-upgrade Facilitymentioning

confidence: 99%

“…The neutral beam current drive [50][51][52][53][54][55][62][63][64] is computed by the NUBEAM code [65]; 8000 to 16000 particles were typically used in these simulations, weighted toward the plasma core to reduce the Monte-Carlo noise on the central beam current drive (wghta=10 [65]). The beam-current shielding factor derived by Lin-Liu & Hinton [64] is used.…”

Section: Free-boundary Transp Simulationsmentioning

confidence: 99%

Exploration of the Equilibrium Operating Space For NSTX-Upgrade

Gerhardt¹

2012

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“…Off-axis NBI has been used to investigate sawtooth behavior in JET [8], MAST and ASDEX-U [9]. By drift kinetic modeling, they have found that the stability of n = 1 internal kink mode, which is thought to be related to sawtooth instability, is destabilized by the passing ions born outside the q = 1 rational surface due to the NBI.…”

Section: The Capability To Control Mhd Activitiesmentioning

confidence: 99%

“…Reasonable agreement between the measured and calculated (with D b ∼ 0-0.5 m 2 s −1 ) NBCD related physical quantities in all of the tokamak plasmas without magnetohydrodynamic (MHD) activities, except ELMs, have been published [1][2][3][4][5][6][7]. In JET [8], ASDEX-U and MAST [9], the experimental results showed that it is possible to control sawtooth by off-axis NBI with an off-axis peaked fast ion distribution.…”

Section: Introductionmentioning

confidence: 99%