A flare-associated mechanism for solar surges

Carlqvist, Per

doi:10.1007/bf00174540

Cited by 41 publications

(5 citation statements)

References 21 publications

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“…LCR models (named after the usual symbols in electric components for inductance L, capacitance C and resistance R) were also developed extensively for MHD waves in coronal loops (see Stepanov et al, 2012, and reference therein). In such models, the magnetic twist in the loop behaves as a current system with its source in the photosphere and equivalent electric resistivity and inductance in the corona (see e.g., Spicer, 1977;Carlqvist, 1979). However, it is still unclear how this LCR model relates to MHD models of coronal loop oscillations (based on e.g.…”

Section: Brief Historical Overviewmentioning

confidence: 99%

Coronal Heating by MHD Waves

et al. 2020

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The heating of the solar chromosphere and corona to the observed high temperatures, imply the presence of ongoing heating that balances the strong radiative and thermal conduction losses expected in the solar atmosphere. It has been theorized for decades that the required heating mechanisms of the chromospheric and coronal parts of the active regions, quiet-Sun, and coronal holes are associated with the solar magnetic fields. However, the exact physical process that transport and dissipate the magnetic energy which ultimately leads to the solar plasma heating are not yet fully understood. The current understanding of coronal heating relies on two main mechanism: reconnection and MHD waves that may have various degrees of importance in different coronal regions. In this review we focus on recent advances in our understanding of MHD wave heating mechanisms. First, we focus on giving an overview of observational results, where we show that different wave modes have been discovered in the corona in the last decade, many of which are associated with a significant energy flux, either generated in situ or pumped from the lower solar atmosphere. Afterwards, we summarise the recent findings of numerical modelling of waves, motivated by the observational results. Despite the advances, only 3D MHD models with Alfvén wave heating in an unstructured corona can explain the observed coronal temperatures compatible with the quiet Sun, while 3D MHD wave heating models including cross-field density structuring are not yet able to account for the heating of coronal loops in active regions to their observed temperature.

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Section: Brief Historical Overviewmentioning

confidence: 99%

Coronal Heating by MHD Waves

et al. 2020

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“…In a later iteration of this model, Carlqvist (1979) demonstrated how part of the energy, previously stored in the twisted field structure, arrives at the double layer as a Poynting flux. Figure 24 illustrates an electrostatic double layer introduced into a (twisted) coronal loop, leading to a radial electrostatic field on its boundary (due to its finite radial extent).…”

Section: Fixed Circuit (Single Loop) Flare Modelsmentioning

confidence: 97%

“…Field-aligned acceleration by parallel electric fields is much more explored in pulsar and terrestrial magnetospheres than in solar flares; the literature dealing the obvious solar analogies is small. Field-aligned potential drops were part of the early current-interruption models of Alfvén and Carlqvist (1967) and Carlqvist (1979) mentioned in Section 3.3, but the basic problem with these is that for the inferred currents the parallel potential drops generated are of the order 10 10 V, much higher than the typical electron energy. A more complex geometry is needed, and current fragmentation may provide the solution.…”

Section: Current Circuits and Flare Particle Accelerationmentioning

confidence: 99%

Electric Current Circuits in Astrophysics

2014

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Cosmic magnetic structures have in common that they are anchored in a dynamo, that an external driver converts kinetic energy into internal magnetic energy, that this magnetic energy is transported as Poynting flux across the magnetically dominated structure, and that the magnetic energy is released in the form of particle acceleration, heating, bulk motion, MHD waves, and radiation. The investigation of the electric current system is particularly illuminating as to the course of events and the physics involved. We demonstrate this for the radio pulsar wind, the solar flare, and terrestrial magnetic storms.

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“…also Carlqvist (1969Carlqvist ( , 1972Carlqvist ( , 1979a, Hasan and ter Haar (1978), Joyce and Hubbard (1978), Goertz and Borovsky (1983), Borovsky (1983Borovsky ( , 1988, Tapping (1987) and the literature cited in the reviews by Carlqvist (1972), Block (1978), Torven (1979), Smith (1982a and Raadu (1989). The current-interruption model as originally proposed involves a single strong double layer.…”

Section: Strong Double Layer Modelsmentioning

confidence: 98%

Particle Acceleration Processes in the Solar Corona

Melrose¹

1990

Aust. J. Phys.

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Theoretical ideas on particle acceleration associated with solar flares are reviewed. A historical outline is used to introduce the various acceleration mechanisms. These are stochastic acceleration in its various forms, diffusive acceleration at shock fronts, shock drift acceleration, resonant acceleration, acceleration during magnetic reconnection and acceleration by parallel electric fields in double layers or electrostatic shocks. Particular emphasis is placed on so-called first phase acceleration of electrons in solar flares, which is conventionally attributed to bulk energisation of electrons (Ramaty et al. 1980). There is no widely accepted theory for bulk energisation, which may be regarded as an enhanced form of heating. Ideas on bulk energisation are discussed critically. It is argued that the dissipation cannot be due to classical resistivity and involves anomalous resistivity or hyperresistivity, e.g., in multiple double layers. The dissipation must occur in very many localised regions. Bulk energisation due to magnetic reconnection is discussed briefly. A model for bulk energisation due to the continual formation and decay of weak double layers is outlined

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A flare-associated mechanism for solar surges

Cited by 41 publications

References 21 publications

Coronal Heating by MHD Waves

Coronal Heating by MHD Waves

Electric Current Circuits in Astrophysics

Particle Acceleration Processes in the Solar Corona

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