Application of dynamic mode decomposition to rotating structures in detached linear plasmas

Natsume, Hiroki; Tanaka, Hirohiko; Kajita, Shin; Ohno, Noriyasu

doi:10.1063/1.5134869

Cited by 7 publications

(4 citation statements)

References 19 publications

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“…This method can be used to study the dependence on various parameters, ex-cept for phenomena that depend on time derivatives. To investigate such the phenomena with time-transient modes, the dynamic mode decomposition (DMD) [21][22][23][24] can be used.…”

Section: Discussionmentioning

confidence: 99%

Correlation of the Orthogonal Basis of the Core Plasma Distribution to the Divertor Footprint Distribution in LHD

Tanaka

Masuzaki

Kawamura

et al. 2023

Plasma and Fusion Research

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We have applied the multivariable analysis technique called the proper orthogonal decomposition (POD) to both the divertor particle flux distribution and the electron pressure distribution in the core region of LHD. The cross-correlation analysis indicates that 3rd, 4th, and 5th POD modes of the electron pressure distribution are highly correlated with the divertor footprint index which is a measure of where the peak position of the particle flux distribution is located on the inner divertor plate. Both the 3rd and 4th modes seem to correspond to the shift of the electron pressure peak position from the magnetic-axis radius. In contrast, 5th mode has a strong influence on the peripheral gradient of the electron pressure distribution. Their relationships with the divertor footprint could be explained by the finite β and the Pfirsch-Schlüter current effects.

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Section: Discussionmentioning

confidence: 99%

Correlation of the Orthogonal Basis of the Core Plasma Distribution to the Divertor Footprint Distribution in LHD

Tanaka

Masuzaki

Kawamura

et al. 2023

Plasma and Fusion Research

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“…More recently, dynamic mode decomposition (DMD) has been proposed in the research field of fluid dynamics, [7][8][9][10] and has attracted attention in many other fields, [11][12][13][14] including plasma physics. [15][16][17][18] This is more suitable to extract structures restricted to the oscillator form which may be growing or decaying. DMD performs fitting with the more constrained equation than Fourier analysis, so if it can be fitted accurately, it is likely to be useful for future prediction.…”

Section: Introductionmentioning

confidence: 99%

A new combination of Hankel and sparsity-promoting dynamic mode decompositions and its application to the prediction of plasma turbulence

Kusaba

Kuboyama

Shin

et al. 2021

Jpn. J. Appl. Phys.

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A new combined use of dynamic mode decomposition algorithms is proposed, which is suitable for the analysis of spatiotemporal data from experiments with few observation points, unlike computational fluid dynamics with many observation points. The method was applied to our data from a plasma turbulence experiment. As a result, we succeeded in constructing a quite accurate model for our training data and it made progress in predictive performance as well. In addition, modal patterns from the longer-term analysis help to understand the underlying mechanism more clearly, which is demonstrated in the case of plasma streamer structure. This method is expected to be a powerful tool for the data-driven construction of a reduced-order model and a predictor in plasma turbulence research and also any nonlinear dynamics researches of other applied physics fields.

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“…Such a correlation is expected to expand the width of the heat flux to the divertor target, i.e., λ q . Thus, the observation and analysis regarding the correlation phenomena have been actively performed in linear devices, e.g., the NAGDIS-II [5,6,7,8,13,14,15,16,17,18,19,20]. However, the physical dynamics of the correlation has not been revealed sufficiently.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the observation and analysis regarding the correlation phenomena have been actively performed in linear devices, e.g. the NAGDIS-II [5][6][7][8][13][14][15][16][17][18][19][20]. However, the physical dynamics of the correlation has not been * Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Linear analysis of cross-field dynamics with feedback instability on detached divertor plasmas

Hasegawa¹,

Tanaka²,

Ishiguro³

2021

Nucl. Fusion

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The theoretical model of the feedback instability is proposed to explain the mechanism of the correlation between the detachment and the cross-field plasma transport. It is shown that the feedback instability on the detached divertor plasma can be induced in a certain condition in which the volume recombination frequency is larger than the ion cyclotron frequency in the recombination region. Further, the density gradient and the electric field in the direction perpendicular to the magnetic flux surface are not zero in the condition. The feedback instability can provide the cross-field plasma transport in the boundary layer of magnetic fusion torus devices. Furthermore, the properties of the radial transport observed in the NAGDIS-II linear device experiment are compared with the estimation by the feedback instability model. The dependence of the feedback instability mode on the total collision frequency and the recombination coefficient and the density gradient has been also investigated. Although the dependency on the total collision frequency and the recombination coefficient for the typical fusion torus device case is opposite to that for the NAGDIS-II case, the represented dependencies show the reasonable tendency in each case.

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Application of dynamic mode decomposition to rotating structures in detached linear plasmas

Cited by 7 publications

References 19 publications

Correlation of the Orthogonal Basis of the Core Plasma Distribution to the Divertor Footprint Distribution in LHD

Correlation of the Orthogonal Basis of the Core Plasma Distribution to the Divertor Footprint Distribution in LHD

A new combination of Hankel and sparsity-promoting dynamic mode decompositions and its application to the prediction of plasma turbulence

Linear analysis of cross-field dynamics with feedback instability on detached divertor plasmas

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