Analysis of Alfven eigenmode destabilization in ITER using a Landau closure model

Varela, J.; Garcia, L.

doi:10.1088/1741-4326/ab1ebe

Cited by 13 publications

(12 citation statements)

References 94 publications

(133 reference statements)

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“…The present model was already used to study the stability of RBM in DIII-D discharges with high poloidal β [67], AE stability in DIII-D, ITER, LHD and TJ-II [68][69][70][71] as well as the EIC in LHD [48], indicating reasonable agreement with the observations.…”

Section: Equations and Numerical Schemesupporting

confidence: 80%

MHD stability of JT-60SA operation scenarios driven by passing energetic particles for a hot Maxwellian model

Varela¹,

Watanabe²,

Shinohara³

et al. 2020

Nucl. Fusion

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Datasets of mobile phone trajectories collected by network operators offer an unprecedented opportunity to discover new knowledge from the activity of large populations of millions. However, publishing such trajectories also raises significant privacy concerns, as they contain personal data in the form of individual movement patterns. Privacy risks induce network operators to enforce restrictive confidential agreements in the rare occasions when they grant access to collected trajectories, whereas a less involved circulation of these data would fuel research and enable reproducibility in many disciplines. In this work, we contribute a building block towards the design of privacy-preserving datasets of mobile phone trajectories that are truthful at the record level. We present GLOVE, an algorithm that implements 𝑘-anonymity, hence solving the crucial unicity problem that affects this type of data while ensuring that the anonymized trajectories correspond to real-life users. GLOVE builds on original insights about the root causes behind the undesirable unicity of mobile phone trajectories, and leverages generalization and suppression to remove them. Proof-of-concept validations with large-scale real-world datasets demonstrate that the approach adopted by GLOVE allows preserving a substantial level of accuracy in the data, higher than that granted by previous methodologies.

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Section: Equations and Numerical Schemesupporting

confidence: 80%

MHD stability of JT-60SA operation scenarios driven by passing energetic particles for a hot Maxwellian model

Varela¹,

Watanabe²,

Shinohara³

et al. 2020

Nucl. Fusion

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“…Similar multiple EP population effects were observed in TFTR plasma; AEs triggered by α particles were only destabilized after the beam injection was stopped [60][61][62]. Recent analysis dedicated to the ITER device also predict multiple EP population effects in plasma with large populations of α particle and NBI EP [57]. It should be noted that the multiple EP effect is different regarding the density profiles, β and temperature of each EP population as it was discussed in previous studies [58].…”

Section: Conclusion and Discussionsupporting

confidence: 59%

“…On the other, the BAEs destabilized by the NBI EP are located near the magnetic axis. Consequently, α particles and NBI EP populations resonate at closer radial location, thus the resulting AE stability of the plasma can be affected by multiple EP population effects that will be evaluated in the following section [57,58].…”

Section: Case B: Itb In the Outer Plasma Regionmentioning

confidence: 99%

Theoretical study of the Alfven eigenmode stability in CFETR steady state discharges

Varela¹,

Huang²,

Spong³

et al. 2022

Nucl. Fusion

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The aim of this study is to analyze the stability of Alfven Eigenmodes (AE) in the China Fusion Engineering Test Reactor (CFETR) plasma for steady state operations. The analysis is done using the gyro-fluid code FAR3d including the effect of the acoustic modes, EP Finite Larmor radius damping effects and multiple energetic particle populations. Two high poloidal β scenarios are studied with respect to the location of the internal transport barrier (ITB) at r/a ≈ 0.45 (case A) and r/a ≈ 0.6 (case B). Both operation scenarios show a narrow TAE gap between the inner-middle plasma region and a wide EAE gap all along the plasma radius. The AE stability of CFETR plasmas improves if the ITB is located inwards, case A, showing AEs with lower growth rates with respect to the case B. The AEs growth rate is smaller in the case A because the modes are located in the inner-middle plasma region where the stabilizing effect of the magnetic shear is stronger with respect to the case B. Multiple EP populations effects (NBI driven EP + alpha articles) are negligible for the case A, although the simulations for the case B show a stabilizing effect of the NBI EP on the n=1 BAE caused by alpha particles during the thermalization process. If the FLR damping effects are included in the simulations, the growth rate of the EAE/NAE decreases up to 70 %, particularly for n > 3 toroidal families. Low n AEs (n<6) show the largest growth rates. On the other hand, high n modes (n=6 to 15) are triggered in the frequency range of the NAE, strongly damped by the FLR effects.

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“…The effect of the multiple EP species can modify the growth rate and frequency of the AEs and EPMs as it was observed in the TFTR experiment [55,56,57], as well as in theoretical studies that analyzed the stabilizing effect of the NBI driven EP on the AEs caused by α particle in ITER plasma and the AE stability in LHD /DIII-D plasma heated by multiple NBI lines [58,59]. In the case of LHD discharges with EIC events, two different EP components coexist: the passing EP particles driven by the tangential NBI and the helically trapped EP driven by the perpendicular NBI.…”

Section: Multiple Ep Componentsmentioning

confidence: 97%

Theoretical analysis of energetic-ion-driven resistive interchange mode stabilization strategies using a Landau closure model

et al. 2020

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The aim of the present study is to perform a theoretical analysis of different strategies to stabilize energetic-ion-driven resistive interchange mode (EIC) in LHD plasma. We use a reduced MHD for the thermal plasma coupled with a gyrofluid model for the energetic particles (EP) species. The hellically trapped EP component is introduced through a modification of the drift frequency to include their precessional drift. The stabilization trends of the 1/1 EIC observed experimentally with respect to the thermal plasma density and temperature are reproduced by the simulations, showing a reasonable agreement with the data. The LHD operation scenarios with stable 1/1 EIC are identified, leading to the stabilization of the 1/1 EIC if the thermal plasma density and temperature are above a given threshold. The 1/1 EIC are also stabilized if the rotational transform is modified in a way that the 1/1 rational surface is located further away than 0.9 times the normalized radius, or the magnetic shear in the plasma periphery is enhanced. Also, LHD discharges with large magnetic fields show a higher EIC destabilization threshold with respect to the thermal plasma density. If the perpendicular NBI deposition region is moved further inward than 0.875 times the normalized radius the 1/1 EIC are also stabilized. In addition,

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Analysis of Alfven eigenmode destabilization in ITER using a Landau closure model

Cited by 13 publications

References 94 publications

MHD stability of JT-60SA operation scenarios driven by passing energetic particles for a hot Maxwellian model

MHD stability of JT-60SA operation scenarios driven by passing energetic particles for a hot Maxwellian model

Theoretical study of the Alfven eigenmode stability in CFETR steady state discharges

Theoretical analysis of energetic-ion-driven resistive interchange mode stabilization strategies using a Landau closure model

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