Locked mode detection during error field identification studies

Piron, L.; Buratti, P.; Falessi, M.; Gambrioli, M.; Graham, G.; Lennhol, M.; Valcarcel, D.F.; Zonca, F.; Henriques, R.; Gerasimov, S.; Hender, T.; Joffrin, E.; Kirov, K.; Mitchell, J.; Pucella, G.; Sauter, O.; Szepesi, G.; Terranova, D.; Zanca, P.

doi:10.1016/j.fusengdes.2023.113957

Cited by 7 publications

(4 citation statements)

References 31 publications

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“…On the other hand, for the offline analyses, the dynamics of the locked mode has also been investigated, besides the commonly used observers (i.e. density drop, temperature flattening), through a novel approach which consists in looking for signatures of Beta Alfvén Eigenmodes, as proposed in [22,23]. The locked mode formation is indeed accompanied by the appearance of MHD activities in the Mirnov spectrogram, which correspond to two lines with initially slightly different frequencies, i.e.…”

Section: A New Methods For Ef Identificationmentioning

confidence: 99%

“…However, during the non-disruptive compass scan tests, a procedure that allows magnetic measurements to be compensated from the external magnetic fields induced by the EF actuators, needs to be applied to guarantee a robust and high fidelity mode detection. For this purpose, studies have been carried out at JET to define new locked mode detectors for initiating the magnetic island healing as reported in [22]. Thanks to their simplicity and robustness, such locked mode detectors can be straightforwardly applied in the ITER plasma control system and be exploited during EF detection pulses scheduled in the first ITER plasma operations.…”

Section: A New Methods For Ef Identificationmentioning

confidence: 99%

“…During EF identification studies, the magnetic field measurements used in input to the real-time detector shall be compensated by the external magnetic field induced by the EF actuators in order to guarantee a reliable and robust detection of the locked mode formation. As documented in [22], an ad-hoc locked mode detector algorithm, based on compensated magnetic field measurements, has been designed and successfully tested at JET and paves the way for its exploitation in ITER and beyond.…”

Section: Development Of Controllers For Ef Identification In Itermentioning

confidence: 99%

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Error field detection and correction studies towards ITER operation

Piron,

Paz-Soldan,

Pigatto

et al. 2024

Nucl. Fusion

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In magnetic fusion devices, error field sources, spurious magnetic field perturbations, need to be identified and corrected for safe and stable (disruption-free) tokamak operation. Within Work Package Tokamak Exploitation RT04, a series of studies have been carried out to test the portability of the novel non-disruptive method, designed and tested in DIII-D (Paz-Soldan C. et al, Nuclear Fusion 62 (2022) 126007), and to perform an assessment of model-based EF control strategies towards their applicability in ITER. In this paper, the lessons learned, the physical mechanism behind the magnetic island healing, which relies on enhanced viscous torque that acts against the static electro-magnetic torque, and the main control achievements are reported, together with the first design of the asynchronous EF correction current/density controller for ITER.

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Section: A New Methods For Ef Identificationmentioning

confidence: 99%

Section: A New Methods For Ef Identificationmentioning

confidence: 99%

Section: Development Of Controllers For Ef Identification In Itermentioning

confidence: 99%

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Error field detection and correction studies towards ITER operation

Piron,

Paz-Soldan,

Pigatto

et al. 2024

Nucl. Fusion

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“…The Beta-induced AE (BAE) [11], within a low-frequency gap induced by the compressional response of the plasma to shear Alfvén waves in the presence of finite pressure and curvature, was observed firstly in the DIII-D tokamak plasma with energetic ions [12]. Subsequently, BAEs accompanied by strong tearing modes were observed in ohmic plasmas without energetic particles [13][14][15][16], prompting consideration of a possible new mechanism for its excitation. Previous observations have shown that there is a critical threshold of magnetic island width for the BAE excitation [13,15], and that the BAE behaves as a pair of waves propagating in opposite directions poloidally and toroidally, forming a standing wave structure [17].…”

Section: Introductionmentioning

confidence: 99%

First observation of beta-induced Alfvén eigenmode inside the edge magnetic island on the J-TEXT tokamak

Yang,

Liang,

Wang

et al. 2024

Nucl. Fusion

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Experiments conducted on the J-TEXT tokamak have provided the first evidence that the beta-induced Alfvéneigenmode (BAE) is localized inside the isolated helical flux tube of its edge m/n = 3/1 magnetic island. The observationsshow that the BAE forms a standing wave inside the magnetic island, with its nodes located at the X- and O-points of themagnetic island. When the island is cut open by contact with the limiter plates, the BAE is found to remain inside theremnant closed island in the scrape-off layer (SOL), but its amplitude decreases as the width of the remnant islandbecomes smaller. These observations are inconsistent with the current theoretical understanding of BAEs, which predictsthe BAE to be positioned outward of the island separatrix.

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