Numerical study on the influence of electron cyclotron current drive on tearing mode

Chen, Long; Liu, Jinyuan; Duan, Ping; Mao, Aohua; Sun, Jizhong

doi:10.1063/1.4897396

Cited by 7 publications

(5 citation statements)

References 34 publications

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“…3(b) that at the end of the red lines, the island width reduces to a minimum and starts to grow at a high rate. This kind of phenomenon has been observed and investigated in several works [46][47][48] and also in our former work; 45 it occurs mainly because that the driven current is relatively excessive after the instability is eliminated. Since the driven current causes that the island topology has a spatial phase shift, the O-point moves aside and the center position is replaced by an X-point pattern reconnection.…”

Section: A Evolution Of Ntms and Effects Of Eccdmentioning

confidence: 91%

“…The deposition locations are generally either at the X-point or at the O-point of the magnetic island, but most experimental studies indicate that O-point deposition can achieve better suppression results, which has also been confirmed in our previous study. 45 In this work, our attention is mainly focused on O-point deposition; therefore, the deposition location of external current should be distributed mainly inside the magnetic island, as shown in Fig. 1(b).…”

Section: Modelmentioning

confidence: 99%

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Modeling of the influences of electron cyclotron current drive on neoclassical tearing modes

et al. 2015

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Influences of external current drive on neoclassical tearing modes are studied numerically with a set of compressible magnetohydrodynamics equations. By considering the effects of driven current parameters and its deposition timing, and by examining the relationship between driven current and the missing bootstrap current, the basic requirements of deposition width and external current density for effectively suppressing neoclassical tearing modes are investigated. When the driven current density is able to compensate the missing bootstrap current and the deposition region is comparable with the saturated island, the suppression results are notable. Meanwhile, the preemptive strategy of current deposition reported experimentally is also evaluated, and the results agree with the experimental ones that early current deposition can enhance suppression effectiveness greatly. In addition, the deficiencies of continuous driven current are discussed when the plasma rotation has been taken into account, and the application of modulated current drive, which is synchronized in phase with the rotating island, can restore the stabilizing role under some conditions. The favorable parameters of modulation such as duty cycle are also addressed. V C 2015 AIP Publishing LLC. [http://dx.

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Section: A Evolution Of Ntms and Effects Of Eccdmentioning

confidence: 91%

Section: Modelmentioning

confidence: 99%

Modeling of the influences of electron cyclotron current drive on neoclassical tearing modes

et al. 2015

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“…In former studies it is validated that the driven current can suppress the island width both at the O and X point of the magnetic island. But the current direction in these two cases should be opposite [40,41]. Figure 1(b) shows the distribution of external driven current density at the simulation region.…”

Section: Simulation Modelmentioning

confidence: 96%

“…With the island rotation considered, modulated current drive has the advantage of higher power effectiveness compared to continuous current drive. The reason for this is that modulated current with a small duty cycle cannot provide enough suppression force, and when the duty cycle exceeds 0.7, a larger portion of current is deposited outside of the island; when the deposition center moves away from the O-point to the X-point, the driven current plays a destabilizing In the previous study we have demonstrated that without considering island rotation, the suppression ability increases with the input energy [41,42]; but if the duty cycle is too large ( ) t > 0.7 , the suppression ability is undesirable and the driven current can barely influence the outcome no matter how large it is.…”

Section: The Effects Of Modulated Current Drivementioning

confidence: 99%

Modeling of the influences of multiple modulated electron cyclotron current drive on NTMs in rotating plasma

Chen¹,

Liu²,

Duan

2017

Plasma Sci. Technol.

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In this work, physical models of neoclassical tearing modes (NTMs) including bootstrap current and multiple modulated electron cyclotron current drive model are applied. Based on the specific physical problems during the suppression of NTMs by driven current, this work compares the efficiency of continuous and modulated driven currents, and simulates the physical processes of multiple modulated driven currents on suppressing rotating magnetic island. It is found that when island rotates along the poloidal direction, the suppression ability of continuous driven current can be massively reduced due to current deposition outside the island separatrix and reverse deposition direction at the X point, which can be avoided by current drive modulation. Multiple current drive has a better suppressing effect than single current drive. This work gives realistic numerical simulations by optimizing the model and parameters based on the experiments, which could provide references for successful suppression of NTMs in future advanced tokamak such as international thermonuclear experimental reactor.

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“…The driven current with larger magnitude and more focused deposition region has a better suppression effect on the TM instability. The current deposition on the island O-point has better results than that on the X-point [27]. In three-dimension nonlinear full MHD toroidal model, much more accurate meaningful results are given in the real tokamak geometry, such as EAST and ASDEX-Upgrade [28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Influence of stationary driven helical current on the m = 2/n = 1 resistive tearing mode

Yuan

Lu²,

Dong³

2019

Plasma Sci. Technol.

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The influence of stationary driven helical current on tearing mode instability in the m=2/n=1 rational surface is explored numerically using resistive magnetohydrodynamic simulation in cylindrical geometry. The results indicate that the flip instabilities result from the sustained injection of the sufficiently strong helical current driven in the island O-point. The driven helical current induces high order harmonics of instabilities due to the delay of suppressing timing and the increase of its current intensity. With the appropriate current density values, the development of the perturbed kinetic energy can be limited and the occurrence of the flip instabilities can be delayed for a long time. The radial deviation of the current deposition can lead to poor inhibition effect, and the effect of current bias on the boundary is greater than that on the axis.

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Numerical study on the influence of electron cyclotron current drive on tearing mode

Cited by 7 publications

References 34 publications

Modeling of the influences of electron cyclotron current drive on neoclassical tearing modes

Modeling of the influences of electron cyclotron current drive on neoclassical tearing modes

Modeling of the influences of multiple modulated electron cyclotron current drive on NTMs in rotating plasma

Influence of stationary driven helical current on the m = 2/n = 1 resistive tearing mode

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