Spontaneous Emission in Cylindrical Periodically-Layered Structures

Wang, Cheng-Ching; Ye, ZhenCheng-Ching

doi:10.1002/(sici)1521-396x(199908)174:2<527::aid-pssa527>3.0.co;2-b

Cited by 16 publications

(17 citation statements)

References 17 publications

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“…For example, the potential field model is adopted as an reference model in many algorithms (see Metcalf et al 2006), where the ambiguity is resolved by assuming the observed components make an acute angle with the modeled ones. The reference model could also be chosen as a linear force-free field such as that in Wang (1997) and Wang et al (2001). Moon et al (2003) proposed a uniform shear angle method by assuming that the transverse magnetic field makes an acute angle with the azimuth angle of the potential field transverse component plus an additional shear angle.…”

Section: Removing the 180 • Ambiguity Of The Transverse Componentsmentioning

confidence: 99%

Origin and structures of solar eruptions II: Magnetic modeling

Guo

Cheng

Ding

2017

Sci. China Earth Sci.

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The topology and dynamics of the three-dimensional magnetic field in the solar atmosphere govern various solar eruptive phenomena and activities, such as flares, coronal mass ejections, and filaments/prominences. We have to observe and model the vector magnetic field to understand the structures and physical mechanisms of these solar activities. Vector magnetic fields on the photosphere are routinely observed via the polarized light, and inferred with the inversion of Stokes profiles. To analyze these vector magnetic fields, we need first to remove the 180 • ambiguity of the transverse components and correct the projection effect. Then, the vector magnetic field can be served as the boundary conditions for a force-free field modeling after a proper preprocessing. The photospheric velocity field can also be derived from a time sequence of vector magnetic fields. Three-dimensional magnetic field could be derived and studied with theoretical force-free field models, numerical nonlinear force-free field models, magnetohydrostatic models, and magnetohydrodynamic models. Magnetic energy can be computed with three-dimensional magnetic field models or a time series of vector magnetic field. The magnetic topology is analyzed by pinpointing the positions of magnetic null points, bald patches, and quasi-separatrix layers. As a well conserved physical quantity, magnetic helicity can be computed with various methods, such as the finite volume method, discrete flux tube method, and helicity flux integration method. This quantity serves as a promising parameter characterizing the activity level of solar active regions.

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Section: Removing the 180 • Ambiguity Of The Transverse Componentsmentioning

confidence: 99%

Origin and structures of solar eruptions II: Magnetic modeling

Guo

Cheng

Ding

2017

Sci. China Earth Sci.

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“…The topological structure of coronal magnetic fields is an important factor in solar explosive events, and often refers to null points, separatrix surface and separator field lines (Longcope 1996;Priest & Titov 1996;Wang 1997;Pontin et al 2013). They are regions of magnetic connectivity discontinuities and serve as preferred sites for magnetic reconnection.…”

Section: Introductionmentioning

confidence: 99%

Two Episodes of Magnetic Reconnections during a Confined Circular-ribbon Flare

Yang

Zhang

et al. 2018

ApJ

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We analyze a unique event with an M1.8 confined circular-ribbon flare on 2016 February 13, with successive formations of two circular ribbons at the same location. The flare had two distinct phases of UV and EUV emissions with an interval of about 270 s, of which the second peak was energetically more important. The first episode was accompanied by the eruption of a mini-filament and the fast elongation motion of a thin circular ribbon (CR1) along the counterclockwise direction at a speed of about 220 km s −1 . Two elongated spine-related ribbons were also observed, with the inner ribbon co-temporal with CR1 and the remote brightenings forming ∼ 20 s later. In the second episode, another mini-filament erupted and formed a blowout jet. The second circular ribbon and two spine-related ribbons showed similar elongation motions with that during the first episode. The extrapolated 3D coronal magnetic fields reveal the existence of a fan-spine topology, together with a quasi-separatrix layer (QSL) halo surrounding the fan plane and another QSL structure outlining the inner spine. We suggest that continuous null-point reconnection between the filament and ambient open field occurs in each episode, leading to the sequential opening of the filament and significant shifts of the fan plane footprint. For the first time, we propose a compound eruption model of circular-ribbon flares consisting of two sets of successively formed ribbons and eruptions of multiple filaments in a fan-spine-type magnetic configuration.

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“…Magnetic reconnection is believed to be the fundamental process that converts the stored magnetic energy into kinetic energy of accelerated particles and plasma and thermal energy during a flare (Priest & Forbes 2002). In the classical 2D picture, magnetic reconnection can occur at null points, where the magnetic field vanishes (Lau & Finn 1990;Wang 1997). In 3D, the quasi-separatrix layers (QSLs; Démoulin et al 1996), i.e., thin layers characterized by very strong magnetic connectivity gradients, are also preferred sites for current accumulation and energy dissipation Pontin et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional Magnetic Reconnection Triggering an X-class Confined Flare in Active Region 12192

Hou

Yang

et al. 2018

ApJ

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We present an extensive analysis of the X2.0-class confined flare on 2014 October 27 in the great active region AR 12192, observed by the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory. The slipping motion of the substructures within the negative-polarity flare ribbon (R1) and continual reconnection-induced flows during the confined flare are first presented. The substructures within ribbon R1 were observed to slip in opposite directions at apparent speeds of 10-70 km s −1 . The slipping motion exhibited the quasi-periodic pattern with a period of 80-110 s, which can be observed since the flare start and throughout the impulsive phase of the flare. Simultaneously quasi-periodic flows moved along a reverse-S shaped filament, with an average period of about 90 s. The period of reconnection-induced flows is similar to that of the slippage of ribbon substructures, implying the occurrence of quasi-periodic slipping magnetic reconnection. The spectral observations showed that the Si iv line was blueshifted by 50-240 km s −1 at the location of the flows. During the process of the flare, the filament did not show the rise phase and was not associated with any failed eruption. The flare mainly consisted of two sets of magnetic systems, with both of their east ends anchoring in ribbon R1. We suggest that the slipping magnetic reconnection between two magnetic systems triggers the confined flare.

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Spontaneous Emission in Cylindrical Periodically-Layered Structures

Cited by 16 publications

References 17 publications

Origin and structures of solar eruptions II: Magnetic modeling

Origin and structures of solar eruptions II: Magnetic modeling

Two Episodes of Magnetic Reconnections during a Confined Circular-ribbon Flare

Three-dimensional Magnetic Reconnection Triggering an X-class Confined Flare in Active Region 12192

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