On the role of ion heating in ICRF heated discharges in Tore Supra

Eriksson, L.‐G.; Hoang, G. T.; Bergeaud, V.

doi:10.1088/0029-5515/41/1/307

Cited by 66 publications

(81 citation statements)

References 19 publications

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“…The Tore Supra discharges with the co-rotating centre that were included in the scaling appeared to suggest that ripple could be neglected. In ICRF heated Tore Supra discharges, both counter and co-current acceleration of the central plasma has been observed when the power is switched on [28,34]. However, the majority of the ICRF heated Tore Supra discharges with full plasma size, and hence standard large ripple level, appear to be counter rotating [35].…”

Section: -Discussion and Conclusionmentioning

confidence: 99%

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JET intrinsic rotation studies in plasmas with a high normalized beta and varying toroidal field ripple

Nave

Eriksson

Giroud

et al. 2012

Plasma Phys. Control. Fusion

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Understanding the origin of rotation in Ion Cyclotron Resonance Frequency (ICRF) heated plasmas is important for predictions for burning plasmas sustained by alpha particles, being characterized by a large population of fast ions and no external momentum input. The angular velocity of the plasma column has been measured in JET H-mode plasmas with pure ICRF heating for both the standard low toroidal magnetic ripple configuration, of about ~ 0.08% and, for increased ripple values up to 1.5 % [1]. These new JET rotation data were compared with the multi-machine scaling of ref. [2] for the Alfven-Mach number and with the scaling for the velocity change from L-mode into H-mode. The JET data do not fit well any of these scalings that were derived for plasmas that are co-rotating with respect to the plasma-current.With the standard low ripple configuration, JET plasmas with large ICRF heating power and normalized beta, βN ≈1.3, have a very small co-current rotation, with Alfven-Mach numbers significantly below those given by the rotation scaling of ref. [2]. In some cases the plasmas are actually counter-rotating. No significant difference between the H-mode and L-mode rotation is observed. Typically the H-mode velocities near the edge are lower than in Lmodes. With ripple values larger than the standard JET value, between 1% and 1.5%, H-mode plasmas were obtained where both the edge and the core counter rotated. I -IntroductionIntrinsic rotation can play a key role in the performance of future tokamak power plants where the momentum input will be small [3]. In present day tokamak experiments, rotation is mostly driven by the torque coming from the neutral beam injection (NBI). However, in reactors with high NBI power at high beam energy, the torque is expected to be small. The central toroidal rotation velocity for ITER H-mode plasmas with NBI power of 34 MW, was predicted to be in the range of 10-170 km/s [4]. This is lower than currently observed at JET for the same Prandtl number (ratio between momentum and ion heat diffusivity) and with NBI power less than 20 MW [5]. It is important to note that ITER simulations depend on options of momentum transport whose theory is still evolving. For instance, the ITER simulations of ref.[4] do not include any contribution from a momentum pinch which is found to exist in JET NBI discharges [6,7] and other tokamaks [8,9]. This inward pinch will modify the rotation profile in ITER, in particular the peaking of the rotation profile will increase. Understanding of momentum transport is crucial in order to reliably model rotation profiles in ITER and other future devices, however, this is not the scope of this paper. A good overview of momentum transport theory, covering also aspects like residual stress and up-down asymmetry that may affect significantly the rotation profile in ITER, is given in reference [10].As the NBI driven rotation in future machines is presumed to be small, the intrinsic plasma rotation, which occurs in the absence of momentum sources such as NBI, has...

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Section: -Discussion and Conclusionmentioning

confidence: 99%

“…δ TF =0.08% to Tore-Supra with δ TF =7% [28]. Radial velocity profile measurements were not available for all machines.…”

Section: -Comparison Of Jet Rotation Data With the Multi-machine mentioning

confidence: 99%

JET intrinsic rotation studies in plasmas with a high normalized beta and varying toroidal field ripple

Nave

Eriksson

Giroud

et al. 2012

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

show abstract

“…The renewed interest in this decades old problem is due to recent observations of rotation with no "external" torque input in a number of machines, in the high confinement mode ͑H-mode͒, 1-4 the low confinement mode ͑L-mode͒, [5][6][7] as well as internal transport barriers ͑ITBs͒. 8 At the simplest level, the toroidal rotation with no torque input scales with ion pressure, temperature, or its gradient, whether the confinement is enhanced or not.…”

Section: Introductionmentioning

confidence: 99%

Residual parallel Reynolds stress due to turbulence intensity gradient in tokamak plasmas

et al. 2010

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A novel mechanism for driving residual stress in tokamak plasmas based on k ʈ symmetry breaking by the turbulence intensity gradient is proposed. The physics of this mechanism is explained and its connection to the wave kinetic equation and the wave-momentum flux is described. Applications to the H-mode pedestal in particular to internal transport barriers, are discussed. Also, the effect of heat transport on the momentum flux is discussed.

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“…As a result, reaching the operational point with higher Q can be done faster with less auxiliary heating power than for an electron heating scenario [1]. In addition, Tore Supra experiments demonstrated that higher levels of ion heating were accompanied by an improved energy confinement [2].…”

Section: Introductionmentioning

confidence: 99%

A new ion cyclotron range of frequency scenario for bulk ion heating in deuterium-tritium plasmas: How to utilize intrinsic impurities in our favour

Kazakov¹,

Ongena²,

Eester³

et al. 2015

Physics of Plasmas

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A fusion reactor requires plasma pre-heating before the rate of deuterium-tritium fusion reactions becomes significant. In ITER, radiofrequency (RF) heating of 3 He ions, additionally puffed into the plasma, is one of the main options considered for increasing bulk ion temperature during the ramp-up phase of the pulse. In this paper, we propose an alternative scenario for bulk ion heating with RF waves, which requires no extra 3 He puff and profits from the presence of intrinsic Beryllium impurities in the plasma. The discussed method to heat Be impurities in D-T plasmas is shown to provide an even larger fraction of fuel ion heating.

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On the role of ion heating in ICRF heated discharges in Tore Supra

Cited by 66 publications

References 19 publications

JET intrinsic rotation studies in plasmas with a high normalized beta and varying toroidal field ripple

JET intrinsic rotation studies in plasmas with a high normalized beta and varying toroidal field ripple

Residual parallel Reynolds stress due to turbulence intensity gradient in tokamak plasmas

A new ion cyclotron range of frequency scenario for bulk ion heating in deuterium-tritium plasmas: How to utilize intrinsic impurities in our favour

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