Optimization of the Magnetic Sensor Configuration for JT-60SA Plasma Control

Takechi, M.; Suzuki, Mitsuhiro; Miyata, Yasumitsu; Kurihara, Kenichi; Suzuki, Takahiro; Ide, S.

doi:10.1585/pfr.13.3402118

Cited by 3 publications

(3 citation statements)

References 8 publications

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“…First, we assume Gaussian noises as a disturbance of the magnetic diagnostics. The maximum noise for the magnetic field diagnostics is 1 G and that for the flux loop diagnostics is 0.5 mWb [15], respectively, which is empirically determined from the JT-60U experiment and will be validated through the JT-60SA integrated commissioning. In the simulation, we applied the Gaussian noises at each control time-step (250 µs) with a variance σ = 1/3 G for the magnetic field, and 1/6 mWb for the magnetic flux.…”

Section: Resilience To Noises In Diagnosticsmentioning

confidence: 96%

Adaptive Tikhonov regularization and dynamic control points for accurate shape parameter control of plasmas

Inoue,

Kojima,

Miyata

et al. 2023

Nucl. Fusion

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Precise control of plasma shape parameters, such as elongation and triangularity is duly needed to achieve high-performance tokamak plasmas, for which we propose adaptive search schemes of 1) optimum regularization parameter for the Tikhonov regularization, and 2) control points to specify the key shape parameters such as elongation and triangularity. Many control points that exceed the number of actuator coils become an ill-conditioned problem, which is successfully resolved by Tikhonov regularization with adaptively optimized free parameters. Furthermore, we develop dynamically changed control points by using the Cauchy Condition Surface scheme, where elongation and triangularity become direct control values. By virtue of both the adaptive Tikhonov regularization scheme and the dynamic control point, we achieved accurate shape control with elongation up to 1.93 and triangularity up to 0.65, where the allowable speed for the change of the elongation is 0.1/s. We also verified the resilience of our developed our logics to the noises. The sequence of the result will contribute to enhance equilibrium controllability in upcoming JT-60SA experiments and provide the robust shape parameter control scheme for ITER and DEMO.

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Section: Resilience To Noises In Diagnosticsmentioning

confidence: 96%

Adaptive Tikhonov regularization and dynamic control points for accurate shape parameter control of plasmas

Inoue,

Kojima,

Miyata

et al. 2023

Nucl. Fusion

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show abstract

“…First, we assume Gaussian noises as a disturbance of the magnetic diagnostics. The maximum noise for the magnetic field diagnostics is 1 G and that for the flux loop diagnostics is 0.5 mWb [18], respectively, which is empirically determined from the JT-60U experiment and will be validated through the JT-60SA integrated commissioning. In the simulation, we applied the Gaussian noises at each control time-step (250 μs) with a variance σ = 1/3 G for the magnetic field, and 1/6 mWb for the magnetic flux.…”

Section: Typical Scenarios For VI Classificationmentioning

confidence: 96%

A new vertical instability predictor via precursor oscillation detection with performance monitoring of equilibrium controller

Inoue¹,

Miyata²,

Urano³

et al. 2022

Nucl. Fusion

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We first propose an accurate and robust vertical instability (VI) predictor by using a support vector machine (SVM), one of the machine learning methods. The SVM is trained to detect precursor oscillation by using newly introduced classification parameters to measure the equilibrium controller performance, which is obtained by the adaptive voltage allocation scheme [S. Inoue, Y. Miyata, H. Urano, T. Suzuki, Nuclear Fusion 61 (9) (2021) 096009]. Furthermore, multi-layered preprocessing filters are newly introduced for the SVM training/prediction, which improves the prediction accuracy under highly imbalanced conditions, where ∼ 500 disruptive data while ∼ 3 × 10^6 non-disruptive data. The classification parameters can be calculated only by the current centroid, which suggests that the proposed predictor is robust against the extrapolation for the experiment and will be validated in JT-60SA experiments.

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“…Here we assume Gaussian noises as a disturbance of the magnetic diagnostics. The maximum noise for the magnetic field diagnostics is 1 G and that for the flux loop diagnostics is 0.5 mWb [18], respectively, which is empirically determined from the JT-60U experiment and will be validated through the JT-60SA integrated commissioning. In the simulation, we applied the Gaussian noises at each control time-step (250 μs) with a variance σ = 1/3 G for the magnetic field, and 1/6 mWb for the magnetic flux.…”

Section: Simulation Conditionsmentioning

confidence: 96%

Development of JT-60SA equilibrium controller with an advanced ISO-FLUX control scheme in the presence of large eddy currents and voltage saturation of power supplies

et al. 2021

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An advanced ISO-FLUX equilibrium control scheme is developed and implemented in the JT-60SA equilibrium controller. For future fusion reactor, the VDE control by the active superconducting coils is essential due to the absence of in-vessel coils and stabilization plates, and the presence of large gap between plasmas and vacuum vessels with the tritium breeding blanket. Under the circumstances, the equilibrium controller should achieve plasma position/shape control and plasma current control by superconducting coils within limited power supply voltages, where plasma current control affects plasma position/shape control, and vice versa. The newly developed ISO-FLUX control scheme enhances the controllability under the above hybrid control of position/shape and plasma current circumstances. Furthermore, the new scheme also provides good controllability under large eddy currents conditions, which will also be expected in future superconducting tokamaks, such as JT-60SA, ITER, and DEMO due to its large inductance and high target plasma current. The JT-60SA equilibrium controller with the developed scheme is well verified by a magnetohydrodynamic equilibrium control simulator ‘MECS’ and ready for the integrated commissioning of JT-60SA.

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Optimization of the Magnetic Sensor Configuration for JT-60SA Plasma Control

Cited by 3 publications

References 8 publications

Adaptive Tikhonov regularization and dynamic control points for accurate shape parameter control of plasmas

Adaptive Tikhonov regularization and dynamic control points for accurate shape parameter control of plasmas

A new vertical instability predictor via precursor oscillation detection with performance monitoring of equilibrium controller

Development of JT-60SA equilibrium controller with an advanced ISO-FLUX control scheme in the presence of large eddy currents and voltage saturation of power supplies

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