The ionization equilibrium and flare line spectra for the electron distribution with a power-law tail

Dzifčáková, E.; Homola, Martin; Dudík, J.

doi:10.1051/0004-6361/201117065

Cited by 18 publications

(16 citation statements)

References 40 publications

(48 reference statements)

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“…The RHESSI spectra indicated that the emission measure of the n-distribution is much higher than for the Maxwell one (Tables A.7, A.8); so the line spectrum of the n-distribution dominates over the Maxwell spectrum, which agrees with the observations (Dzifčáková et al 2011b). Finally, the electron densities of the power-law distribution, as well as of the electrons producing the type III bursts, are too low compared to the other two assumed distributions to have any significant effects on the studied RESIK Si line spectrum; see also the recent results on a combined distribution composed of the n-distribution and the power-law tail (Dzifčáková et al 2011a).…”

Section: Discussionmentioning

confidence: 95%

“…Thus, the ratio Si xiii/Si xiid is extremely sensitive to the shape of the electron distribution function. For detailed information see Dzifčáková et al (2011a), who investigate the influence of the non-thermal plasma bulk and the high-energy tail on the Si ionization and its line spectra. The observed enhanced intensities of satellite lines ) require an increased number of particles at Si xiid energy in comparison to the Maxwell distribution (Figs.…”

Section: Diagnostics Of the N-distributionmentioning

confidence: 99%

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Diagnostics of non-thermal distributions in solar flare spectra observed by RESIK and RHESSI

Kulinová

Kašparová

Dzifčáková

et al. 2011

A&A

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Context. During solar flares an enormous amount of energy is released, and the charged particles, like electrons, are accelerated. These non-thermal electrons interact with the plasma in various parts of solar flares, where the distribution function of electrons can therefore be non-Maxwellian. Aims. We focus on the non-thermal components of the electron distribution in the keV range and analyse high-energy resolution X-ray spectra detected by RESIK and RHESSI for three solar flares. Methods. In the 2-4 keV range we assume that the electron distribution can be modelled by an n-distribution. Using a method of line-intensity ratios, we analyse allowed and satellite lines of Si observed by RESIK and estimate the parameters of this n-distribution. At higher energies we explore RHESSI bremsstrahlung spectra. Adopting a forward-fitting approach and thick-target approximation, we determine the characteristics of injected electron beams. Results. RHESSI non-thermal component associated with the electron beam is correlated well with presence of the non-thermal n-distribution obtained from the RESIK spectra. In addition, such an n-distribution occurs during radio bursts observed in the 0.61-15.4 GHz range. Furthermore, we show that the n-distribution could also explain RHESSI emission below ∼5 keV. Therefore, two independent diagnostics methods indicate the flare plasma being affected by the electron beam can have a non-thermal component in the ∼2-5 keV range, which is described by the n-distribution well. Finally, spectral line analysis reveals that the n-distribution does not occupy the same location as the thermal component detected by RHESSI at ∼10 keV.

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Section: Discussionmentioning

confidence: 95%

Section: Diagnostics Of the N-distributionmentioning

confidence: 99%

Diagnostics of non-thermal distributions in solar flare spectra observed by RESIK and RHESSI

Kulinová

Kašparová

Dzifčáková

et al. 2011

A&A

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“…Credit: Kulinová et al (2011), reproduced with permission c ESO. Dzifčáková, Homola, and Dudík (2011) calculated theoretical spectra for a composite np-distribution characterized by a n-distribution bulk and a powerlaw tail. They showed that such a composite distribution is also able to produce enhanced dielectronic satellites, while the Maxwellian distribution with powerlaw tails alone cannot produce this effect.…”

Section: Non-maxwellian Analysis Of X-ray Line Spectramentioning

confidence: 99%

Nonequilibrium Processes in the Solar Corona, Transition Region, Flares, and Solar Wind (Invited Review)

et al. 2017

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We review the presence and signatures of the non-equilibrium processes, both non-Maxwellian distributions and non-equilibrium ionization, in the solar transition region, corona, solar wind, and flares. Basic properties of the non-Maxwellian distributions are described together with their influence on the heat flux as well as on the rates of individual collisional processes and the resulting optically thin synthetic spectra. Constraints on the presence of highenergy electrons from observations are reviewed, including positive detection of non-Maxwellian distributions in the solar corona, transition region, flares, and wind. Occurrence of non-equilibrium ionization is reviewed as well, especially in connection to hydrodynamic and generalized collisional-radiative modelling. Predicted spectroscopic signatures of non-equilibrium ionization depending on the assumed plasma conditions are summarized. Finally, we discuss the future remote-sensing instrumentation that can be used for detection of these non-equilibrium phenomena in various spectral ranges.

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“…Diagnostics for κ based on line intensity ratios have been proposed (Dzifčáková & Kulinová 2011;Dudík et al 2014Dudík et al , 2015. One limitation of the reverse-engineering method has been that it is a complicated process to obtain all of the atomic data necessary to calculate these ratios, and so only data for certain discrete values of κ are available.…”

Section: Level Populations and Line Emissivitiesmentioning

confidence: 99%

A Simple Method for Modeling Collision Processes in Plasmas With a Kappa Energy Distribution

Hahn

Savin

2015

ApJ

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We demonstrate that a nonthermal distribution of particles described by a kappa distribution can be accurately approximated by a weighted sum of Maxwell-Boltzmann distributions. We apply this method to modeling collision processes in kappa-distribution plasmas, with a particular focus on atomic processes important for solar physics. The relevant collision process rate coefficients are generated by summing appropriately weighted Maxwellian rate coefficients.This method reproduces the rate coefficients for a kappa distribution to an estimated accuracy of better than 3%. This is equal to or better than the accuracy of rate coefficients generated using "reverse engineering" methods, which attempt to extract the needed cross sections from the published Maxwellian rate coefficient data and then reconvolve the extracted cross sections with the desired kappa distribution. Our approach of summing Maxwellian rate coefficients is easy to implement using existing spectral analysis software. Moreover, the weights in the sum of the Maxwell-Boltzmann distribution rate coefficients can be found for any value of the parameter κ, thereby enabling one to model plasmas with a timevarying κ. Tabulated Maxwellian fitting parameters are given for specific values of κ from 1.7 to 100. We also provide polynomial fits to these parameters over this entire range. Several applications of our technique are presented, including the plasma equilibrium charge state distribution (CSD), predicting line ratios, modeling the influence of electron impact multiple ionization on the equilibrium CSD of kappa-distribution plasmas, and calculating the time-varying CSD of plasmas during a solar flare.

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The ionization equilibrium and flare line spectra for the electron distribution with a power-law tail

Cited by 18 publications

References 40 publications

Diagnostics of non-thermal distributions in solar flare spectra observed by RESIK and RHESSI

Diagnostics of non-thermal distributions in solar flare spectra observed by RESIK and RHESSI

Nonequilibrium Processes in the Solar Corona, Transition Region, Flares, and Solar Wind (Invited Review)

A Simple Method for Modeling Collision Processes in Plasmas With a Kappa Energy Distribution

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