Invited paper: ICRF/Edge physics research on textor

Oost, G. Van; Nieuwenhove, R. Van; Koch, R.; Messiaen, A.; Vandenplas, P. E.; Weynants, R.; Dippel, K.H.; Finken, K.H.; Lie, Y.T.; Pospieszczyk, A.; Samm, U.; Schweer, B.; Conn, R.W.; Corbett, W.J.; Goebel, Dan M.; Moyer, R. A.

doi:10.1016/0920-3796(90)90075-h

Cited by 35 publications

(20 citation statements)

References 43 publications

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“…The TFR group [5] found that the plasma density and temperature in the whole SOL increase as soon as the radio-frequency (RF) pulse is switched on, and they estimated the RF power involved in the SOL to be about 0.5 W cm −3 . On the TEXTOR tokamak [6,7], the increase of impurities related to ICRH was examined and it was found that the density rise and the metal sputtering occurring with ICRH are mainly due to local ion heating inside the SOL. On the Joint European Torus, JET [8], the main conclusion was that the density and temperature profiles in the SOL flatten and enhanced impurity and neutral influx are observed.…”

Section: Introductionmentioning

confidence: 99%

The role of power and magnetic connection to the active antenna in the suppression of intermittent structures by ion cyclotron resonance heating

2012

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The effect of the ion cyclotron resonance heating (ICRH) on the scrape-off layer (SOL) is still an open issue, where, lately it was shown on the ASDEX-Upgrade tokamak that turbulence large-scale structures, known as blobs or avaloids, are suppressed by ICRH (Antar et al 2010 Phys. Rev. Lett. 105 165001). Furthermore, it was shown that the edge localized mode-induced turbulent transport is also reduced significantly. However, the reasons behind this interaction remain unknown. On the Tore Supra tokamak, we confirm that the ICRH suppresses large-scale structures while small-scale structures are enhanced; overall, the turbulence level of fluctuations is reported to drop from about 40% to 25%. This confirms that the effects on turbulence are independent of the type of plasma confinement, L-mode on Tore Supra versus H-mode on ASDEX-Upgrade. The dependence on the ICRH power showed that if a threshold existed it would be below 500 kW and that above this power, no additional effects on the SOL turbulence are reported. The other study reported in this paper deals with the importance of the magnetic field line connections or, in other words, whether the interaction between ICRH and turbulence is global, affecting the whole plasma, or local, affecting regions that are magnetically connected to the active antenna. We found that the toroidal connection to the active antenna is not critical in the sense that turbulence in regions close to the antenna but not necessarily connected are affected. For regions that are not connected and far from the active antenna, turbulence does not change much when applying ICRH.

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Section: Introductionmentioning

confidence: 99%

The role of power and magnetic connection to the active antenna in the suppression of intermittent structures by ion cyclotron resonance heating

2012

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“…PDI has been observed on NSTX, 1 C-MOD, 2 ASDEX, 3 DIII-D, 4 TEXTOR, 5 and JT-60. 6 It is particularly virulent for direct IBW launch (because of the slow group velocity and hence large amplitude of IBW waves), but has also been observed in conventional (fast wave) ICRF experiments, and has recently been suggested as a possible explanation for observed power loss and concomitant edge ion heating during HHFW experiments on NTSX.…”

Section: Introductionmentioning

confidence: 99%

Towards a Predictive Model of Power Loss from Parametric Decay of ICRF Waves

Myra

Berry²,

Jaeger

2007

AIP Conference Proceedings

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Abstract. Both theory and experiment have suggested that parametric decay instability (PDI) is a possible edge power loss mechanism in ICRF (including HHFW and IBW) heating of tokamak plasmas. In this paper, we consider the extension of previous theoretical models to enable a quantitative evaluation of pump depletion and power loss due to PDI. A set of nonlinear coupled equations for a long-wavelength "dipole" pump and short-wavelength daughter modes is derived. The model recovers the standard PDI dispersion relation for fixed pump wave amplitude, and obeys an appropriate nonlinear energy conservation law. When dissipation is present the model provides a description of energy flow from the pump to the daughter modes and the particles. The equations are intended to describe parametric decay and pump depletion in inhomogeneous plasmas. By writing the nonlinear coupling coefficients in terms of a spectral basis, a strategy for implementing the model in full-wave spectral codes is presented.

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“…With more and more applications of rf waves for plasma heating and current drive on tokamak devices, the interactions between waves and plasmas have been investigated extensively [9][10][11][12][13][14][15][16][17][18]. When the input power of the incident wave reaches a megawatt, nonlinear phenomena occur and cannot be ignored.…”

Section: Introductionmentioning

confidence: 99%

“…When the input power of the incident wave reaches a megawatt, nonlinear phenomena occur and cannot be ignored. The observations of PDI during the ion cyclotron range of frequency (ICRF) heating experiments have been reported on different tokamak devices, such as ASDEX [10], JET [11], TEXTOR [12,13], JT-60 [14], DIII-D [9,15,16], HT-7 [17], Alcator C-Mod [18], etc. In these experiments, the observed decay processes involved (1) resonant decay into two ion Bernstein waves (IBWs), (2) nonresonant decay into an ion cyclotron quasimode (ICQM) plus an IBW, and (3) nonresonant decay into a low-frequency electron quasimode (EQM) and an IBW.…”

Section: Introductionmentioning

confidence: 99%

Particle-in-cell simulations of parametric decay instability of radiofrequency wave in the ion cyclotron range of frequency in an inhomogeneous plasma

Gan

Xiang

et al. 2015

Nucl. Fusion

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Particle-in-cell simulations have been conducted to investigate the parametric decay processes of radiofrequency waves in the ion cyclotron range of frequency in inhomogeneous plasmas. By choosing the parameters close to those in the ion Bernstein wave heating experiments on the HT-7 tokamak (Li et al 2001 Plasma Phys. Control. Fusion 43 1227–38), decay channels similar to experimental observations have been found in simulations. It is shown that due to strong inhomogeneity of tokamak edge plasma, layers may exist where selection rules of the mode–mode coupling are satisfied, and resonant parametric decays can occur if the input wave power is sufficiently high. As a result, daughter waves at half-, second- and third-harmonic frequencies of the pump wave can be excited. The nonresonant parametric decay is also observed, and ions are heated via nonlinear Landau damping.

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Invited paper: ICRF/Edge physics research on textor

Cited by 35 publications

References 43 publications

The role of power and magnetic connection to the active antenna in the suppression of intermittent structures by ion cyclotron resonance heating

The role of power and magnetic connection to the active antenna in the suppression of intermittent structures by ion cyclotron resonance heating

Towards a Predictive Model of Power Loss from Parametric Decay of ICRF Waves

Particle-in-cell simulations of parametric decay instability of radiofrequency wave in the ion cyclotron range of frequency in an inhomogeneous plasma

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