Transport of energetic electrons in a fully ionized hydrogen plasma

Bai, T.

doi:10.1086/160170

Cited by 50 publications

(31 citation statements)

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“…Scattering in angle is unimportant for fast ions and relativistic electrons -the only particles that can reach the LC7 l layer. For non-relativistic electrons it reduces the mean range by 2/3 (Brown, 1972), although dispersion means that electrons will stop and deposit energy over a range of depths up to their full vertical stopping depth (Bai, 1982). For the present purposes of estimation we neglect pitch-angle scattering completely.…”

Section: Discussionmentioning

confidence: 99%

Origin of the 30 THz Emission Detected During the Solar Flare on 2012 March 13 at 17:20 UT

et al. 2015

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Solar observations in the infrared domain can bring important clues on the response of the low solar atmosphere to primary energy released during flares. At present the infrared continuum has been detected at 30 THz (10 µm) in only a few flares. SOL2012-03-13 , which is one of these flares, has been presented and discussed in Kaufmann et al. (2013). No firm conclusions were drawn on the origin of the mid-infrared radiation. In this work we present a detailed multi-frequency analysis of the SOL2012-03-13 event, including observations at radio millimeter and sub-millimeter wavelengths, in hard X-rays (HXR), gamma-rays (GR), Hα, and white-light. HXR/GR spectral analysis shows that SOL2012-03-13 is a GR line flare and allows estimating the numbers of and energy contents in electrons, protons and α particles produced during the flare. The energy spectrum of the electrons producing the HXR/GR continuum is consistent with a broken power-law with an energy break at ∼ 800 keV. It is shown that the high-energy part (above ∼ 800 keV) of this distribution is responsible for the high-frequency radio emission (> 20 GHz) time-independent models of the quiet and flare atmospheres, we find that most (∼80%) of the observed 30 THz radiation can be attributed to thermal freefree emission of an optically-thin source. Using the F2 flare atmospheric model (Machado et al., 1980) this thin source is found to be at temperatures T ∼ 8000 K and is located well above the minimum temperature region. We argue that the chromospheric heating, which results in 80 % of the 30 THz excess radiation, can be due to energy deposition by non-thermal flare accelerated electrons, protons and α particles. The remaining 20% of the 30 THz excess emission is found to be radiated from an optically-thick atmospheric layer at T ∼ 5000 K, below the temperature minimum region, where direct heating by non-thermal particles is insufficient to account for the observed infrared radiation.

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Section: Discussionmentioning

confidence: 99%

Origin of the 30 THz Emission Detected During the Solar Flare on 2012 March 13 at 17:20 UT

et al. 2015

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“…The delays of such duration can be explained by energy dependent trapping of emitting electrons. Note that for a one-loop configuration there should be a progressive delay of peaks emitting by higher-energy electrons due to the effect of Coulomb collisions on the trapped electrons (Bai, 1982). In our case the tendency was the opposite and the delays were shorter at high frequencies.…”

Section: Flare Configurationmentioning

confidence: 54%

Sources of Quasi-periodic Pulses in the Flare of 18 August 2012

et al. 2016

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We analyzed spatial and spectral characteristics of quasi-periodic pulses (QPP) for the 18 August 2012 limb flare, using new data from a complex of spectral and imaging instruments developed by the Siberian Solar Radio Telescope team and the Wind/Konus gamma-ray spectrometer. A sequence of broadband pulses with periods of approximately ten seconds were observed in Xrays at energies between 25 keV and 300 keV, and in microwaves at frequencies from a few GHz up to 34 GHz during an interval of one minute. The QPP Xray source was located slightly above the limb where the south legs of large and small EUV loop systems were close to each other. Before the QPPs the soft X-ray emission and the Ramaty High Energy Solar Spectroscopic Imager signal from the energy channels below 25 keV were gradually arising for several minutes at the same location. It was found that each X-ray pulse showed the soft-hard-soft behavior. The 17 and 34 GHz microwave source were at footpoints of the small loop system and the source emitting in the 4.2 -7.4 GHz band in the large one. The QPPs were probably generated by modulation of acceleration processes in the energy release site. Analyzing radio spectra we determined the plasma parameters in the radio sources. The microwave pulses could be explained by relatively weak variations of the spectrum hardness of emitting electrons.

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“…Flarix is able to model several processes, which according to contemporary and generally accepted flare models occur concurrently in flares and play there important roles. The transport, scattering and progressive thermalization of the beam electrons 234 P. Heinzel et al due to Coulomb collisions with particles of ambient plasma in the magnetized flaring atmosphere and the resulting flare heating corresponding to the local energy losses of beam electrons is calculated using an approach proposed by Bai (1982) and Karlický & Hénoux (1992) based on test particles and Monte Carlo method. This approach, fully equivalent to direct solution of the corresponding Fokker-Planck equation (MacKinnon & Craig 1991), provides a flexible way to model many various aspects of the beam electron interactions with the ambient plasma, converging magnetic field in the flare loop or with additional electric fields (Varady et al 2014).…”

Section: Rhd Code Flarixmentioning

confidence: 99%

Numerical RHD simulations of flaring chromosphere with Flarix

Heinzel¹,

Kašparová²,

Varady

et al. 2015

Proc. IAU

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Abstract. Flarix is a radiation-hydrodynamical (RHD) code for modeling of the response of the chromosphere to a beam bombardment during solar flares. It solves the set of hydrodynamic conservation equations coupled with NLTE equations of radiative transfer. The simulations are driven by high energy electron beams. We present results of the Flarix simulations of a flaring loop relevant to the problem of continuum radiation during flares. In particular we focus on properties of the hydrogen Balmer continuum which was recently detected by IRIS.

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Transport of energetic electrons in a fully ionized hydrogen plasma

Cited by 50 publications

References 0 publications

Origin of the 30 THz Emission Detected During the Solar Flare on 2012 March 13 at 17:20 UT

Origin of the 30 THz Emission Detected During the Solar Flare on 2012 March 13 at 17:20 UT

Sources of Quasi-periodic Pulses in the Flare of 18 August 2012

Numerical RHD simulations of flaring chromosphere with Flarix

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