Flare Loop Radiative Hydrodynamics - Part Six - Chromospheric Evaporation due to Heating by Nonthermal Electrons

1985 ◽  
Vol 289 ◽  
pp. 425 ◽  
Author(s):  
G. H. Fisher ◽  
R. C. Canfield ◽  
A. N. McClymont
Keyword(s):  
Flare Loop ◽  
Nonthermal Electrons ◽  
Chromospheric Evaporation

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

scholarly journals Multiwavelength Quasi-periodic Pulsations in a Stellar Superflare

2021 ◽  
Vol 923 (2) ◽  
pp. L33
Author(s):  
Dmitrii Y. Kolotkov ◽  
Valery M. Nakariakov ◽  
Robin Holt ◽  
Alexey A. Kuznetsov
Keyword(s):  
Ohmic Heating ◽  
Simultaneous Detection ◽  
X Rays ◽  
Flare Loop ◽  
Nonthermal Electrons ◽  
Cool Star ◽  
To Come ◽  
Nonthermal Emissions ◽  
Unique Relationship ◽  
Oscillatory Processes

Abstract We present the first multiwavelength simultaneous detection of quasi-periodic pulsations (QPPs) in a superflare (more than a thousand times stronger than known solar flares) on a cool star, in soft X-rays (SXRs, with XMM-Newton) and white light (WL, with Kepler). It allowed for the first ever analysis of oscillatory processes in a stellar flare simultaneously in thermal and nonthermal emissions, conventionally considered to come from the corona and chromosphere of the star, respectively. The observed QPPs have periods 1.5 ± 0.15 hr (SXR) and 3 ± 0.6 hr (WL), and correlate well with each other. The unique relationship between the observed parameters of QPPs in SXR and WL allowed us to link them with oscillations of the electric current in the flare loop, which directly affect the dynamics of nonthermal electrons and indirectly (via ohmic heating) the thermal plasma. These findings could be considered in favor of the equivalent LCR contour model of a flare loop, at least in the extreme conditions of a stellar superflare.

Kinematics of a System of Loop Prominences

1979 ◽  
Vol 44 ◽  
pp. 237-241 ◽  
Author(s):  
O. Engvold ◽  
E. Jensen ◽  
B.N. Andersen
Keyword(s):  
Loop System ◽  
Mass Motion ◽  
Flare Loop ◽  
Doppler Effects ◽  
Rare Phenomena ◽  
True Mass

A detailed description of the development of loops connected with flares has been given by Bruzek (1964). Data on true mass motion as inferred from Doppler-effects are sparse in the literature as flare loop prominences are rare phenomena (Kleczek 1965). Jefferies and Orrall (1965) reported high velocities near the top of a loop system. Gurtovenko et al. (1969) observed large Doppler velocities in the loop system of July 11th. 1966.

scholarly journals Electrostatic wave breaking limit in a cold electronegative plasma with non-Maxwellian electrons

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
I. S. Elkamash ◽  
I. Kourakis
Keyword(s):  
Wave Breaking ◽  
Density Ratio ◽  
Negative Ions ◽  
First Integral ◽  
Energy Balance Equation ◽  
Plasma Parameters ◽  
Ion Density ◽  
Electrostatic Wave ◽  
Nonthermal Electrons ◽  
Electronegative Plasma

AbstractA one-dimensional multifluid hydrodynamic model has been adopted as basis for an investigation of the role of suprathermal electrons on the wave breaking amplitude limit for electrostatic excitations propagating in an electronegative plasma. A three-component plasma is considered, consisting of two inertial cold ion populations of opposite signs, evolving against a uniform background of (non-Maxwellian) electrons. A kappa-type (non-Maxwellian) distribution function is adopted for the electrons. By employing a traveling wave approximation, the first integral for the fluid-dynamical system has been derived, in the form of a pseudo-energy balance equation, and analyzed. The effect of intrinsic plasma parameters (namely the ion density ratio, the ion mass ratio, and the superthermal index of the nonthermal electrons) on the wave breaking amplitude limit is explored, by analyzing the phase space topology of the associated pseudopotential function. Our results are relevant to particle acceleration in Space environments and to recent experiments based on plasma-based accelerator schemes, where the simultaneous presence of negative ions and nonthermal electrons may be observed.

Sign in / Sign up

Export Citation Format

Share Document