Optimizing beam-ion confinement in ITER by adjusting the toroidal phase of the 3D magnetic fields applied for ELM control

Sanchis-Sanchez, L.; García-Muñoz, M.; Viezzer, E.; Loarte, A.; Li, L.; Liu, Yueqiang; Snicker, A.; Chen, Liu; Zonca, F.; Pinches, S. D.; Zarzoso, D.

doi:10.1088/1741-4326/abdfdd

Cited by 21 publications

(34 citation statements)

References 38 publications

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“…Good confinement of fast ions is crucial for maintaining high performance tokamak operations. 3D field perturbations are well known to affect the transport and loss of fast ions in tokamak plasmas [41][42][43][44][45]. The FI loss due to 3D fields can be particularly severe in relatively high-β N plasmas such as that projected for HL-2M, where the applied vacuum RMP field can be substantially amplified by the plasma response, as shown in this study.…”

Section: Introductionmentioning

confidence: 57%

“…Limitations associated with diagnostic windows on the vacuum vessel determine the location and size of the ELM control coils along the poloidal angle, as shown in figure 1(a). On the other hand, an important freedom, which we will exploit in this study, is the relative toroidal phase (the coil phasing) ΔΦ ≡ Φ U − Φ L of the coil currents between upper and lower rows, for a given toroidal harmonic n. ΔΦ plays a crucial role in tuning the poloidal spectrum of the applied fields [25] as well as in the resulting fast ion loss near the plasma edge [44]. We emphasize that there are only two rows of RMP coils on HL-2M.…”

Section: Equilibrium and Rmp Coil Configurationsmentioning

confidence: 99%

“…These represent passing particles for the equilibrium considered here. A key aspect that we will investigate is the change of the canonical toroidal angular momentum P φ due to the presence of RMP fields [44]. Figure 14 shows one example of a passing fast ion trajectory projected on the poloidal plane.…”

Section: Effect Of Rmp On Fast Ion Confinementmentioning

confidence: 99%

“…Moreover, this resonant field amplification phenomenon, resulting in enhanced 3D perturbations and hence potentially more FI loss, often occurs at the best coil phasing that favors ELM control by the RMP. This points to the importance of simultaneously considering the FI confinement issue when studying the ELM control problem, since the fast ion transport and loss depend on the applied RMP field in terms of the toroidal mode number, the coil amplitude and coil phasing [44,46,47]. This work will therefore also investigate the effect of coil phasing and the plasma response on the FI confinement for the high-β N reference plasma in HL-2M.…”

Section: Introductionmentioning

confidence: 99%

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Toroidal modeling of plasma response to RMP fields for HL-2M

Hao¹,

Li²,

Liu³

et al. 2021

Nucl. Fusion

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The plasma response to the n = 1, 2, 4 (n is the toroidal mode number) resonant magnetic perturbation (RMP) fields, and the consequences on the fast ion confinement, are numerically investigated for a reference high-pressure plasma in HL-2M, by utilizing the linear resistive magnetohydrodynamic code MARS-F (Liu et al 2000 Phys. Plasmas 7 3681). The best coil current configurations, in terms of the coil phasing between the upper and lower rows of coils for controlling type-I edge localized modes (ELMs) in HL-2M, are identified as −130, −30, 180 degrees for the n = 1, 2, 4 fields, respectively, based on the edge peeling-tearing plasma response criterion. The plasma is found to substantially amplify the applied vacuum RMP field with the best coil phasing for the reference HL-2M equilibrium. The overall field amplification factor, defined as the peak-to-peak ratio of the poloidal spectra for the total field perturbation including the plasma response and the vacuum field alone, is about five for all n’s. The amplification, however, does not occur with the worst coil phasing for ELM control. This field amplification due to the high-pressure plasma response, together with the plasma screening of the resonant radial field components in the core region, have several consequences on the fast ion confinement in HL-2M during ELM control with RMP. (i) Three-dimensional fields including the plasma response, and with the best coil phasing, substantially enhance the distortion of fast ion orbits compared to the vacuum field approximation. With the n = 1 RMP, the plasma-response-induced enhancement of the orbit distortion reaches a factor of four when measured in terms of the canonical toroidal angular momentum. (ii) With the best coil phasing, the plasma response widens the stochastic region for the particle orbits on the Poincaré plane. (iii) The orbit islands, including the plasma response, remain as large as the vacuum counterparts in the plasma core where strong screening of the resonant field components occur. All these effects lead to enhanced fast ion transport (and loss) in the high-pressure HL-2M plasma, when the best RMP spectrum is applied to control ELMs.

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Section: Introductionmentioning

confidence: 57%

Section: Equilibrium and Rmp Coil Configurationsmentioning

confidence: 99%

Section: Effect Of Rmp On Fast Ion Confinementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Toroidal modeling of plasma response to RMP fields for HL-2M

Hao¹,

Li²,

Liu³

et al. 2021

Nucl. Fusion

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“…In Ref. 34 , the toroidal phasing is found to have significant effects on the fast ion confinement, where both passing and trapped particles are significant in the fast ion source.…”

Section: Modification Of Radial Profile Of Ion Heating Power Density ...mentioning

confidence: 99%

Effects of resonant magnetic perturbations on neutral beam heating in a tokamak

Hu,

Xu,

Hao

et al. 2021

Preprint

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Effects of resonant magnetic perturbations (RMPs) on tangential neutral beam heating in the EAST tokamak are studied numerically. RMPs with linear resistive magnetohydrodynamics response are used in the modeling. A variety of representing configurations of RMP coil currents are examined and their effects on the NBI heating efficiency are compared, in order to find a parameter window where deleterious effects of RMPs on NBI heating efficiency are minimized. It is found that the internal redistribution of fast ions by RMPs induces local accumulation of fast ions, resulting in higher local fast ion pressure than the case without RMPs. It is also found that the toroidal phasing of the RMP with respect to the fast ion source has slight effects on the steady-state radial profile of fast ions. The dependence of fast ion loss fraction on the RMP up-down phase difference shows similar behavior as the dependence of the radial width of chaotic magnetic field on the phase difference. A statistical method of identifying resonances between RMPs and lost fast ions is proposed and the results indicate that some resonances between RMPs and lost passing particles may be of non-integer fractional order, rather than the usual integer order.

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Effects of resonant magnetic perturbations on neutral beam heating in a tokamak

Hao

et al. 2021

Physics of Plasmas

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The effects of resonant magnetic perturbations (RMPs) on tangential neutral beam heating in the EAST tokamak are studied numerically. RMPs with linear resistive magnetohydrodynamics response are used in the modeling. A variety of representing configurations of RMP coil currents are examined, and their effects on the neutral beam injection (NBI) heating efficiency are compared, in order to find a parameter window where deleterious effects of RMPs on NBI heating efficiency are minimized. It is found that the internal redistribution of fast ions by RMPs induces local accumulation of fast ions, resulting in higher local fast ion pressure than the case without RMPs. It is also found that the toroidal phasing of the RMP with respect to the fast ion source has slight effects on the steady-state radial profile of fast ions. The dependence of fast ion loss fraction on the RMP up-down phase difference shows a similar behavior as the dependence of the radial width of chaotic magnetic field on the phase difference. A statistical method of identifying resonances between RMPs and lost fast ions is proposed, and the results indicate that some resonances between RMPs and lost passing particles may be of non-integer fractional order, rather than the usual integer order.

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Optimizing beam-ion confinement in ITER by adjusting the toroidal phase of the 3D magnetic fields applied for ELM control

Cited by 21 publications

References 38 publications

Toroidal modeling of plasma response to RMP fields for HL-2M

Toroidal modeling of plasma response to RMP fields for HL-2M

Effects of resonant magnetic perturbations on neutral beam heating in a tokamak

Effects of resonant magnetic perturbations on neutral beam heating in a tokamak

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