X-RAY BREMSSTRAHLUNG EMISSION DUE TO PLASMA SUPERTHERMAL ELECTRONS

1987 ◽  
Vol 48 (C9) ◽  
pp. C9-355-C9-358
Author(s):  
M. LAMOUREUX ◽  
R. H. PRATT ◽  
L. JACQUET
Keyword(s):  
Superthermal Electrons ◽  
X Ray ◽  
Bremsstrahlung Emission

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.

80 MHz Survey of Extra-Galactic X-ray Sources

1979 ◽  
Vol 3 (5) ◽  
pp. 332-341 ◽  
Author(s):  
O. B. Slee ◽  
P. J. Quinn
Keyword(s):  
Angular Size ◽  
Virgo Cluster ◽  
Relativistic Electrons ◽  
Clusters Of Galaxies ◽  
Coma Cluster ◽  
Microwave Background ◽  
Significant Information ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Bremsstrahlung Emission

The completion of the Uhuru (Forman et al. 1978) and Ariel V (Cooke et al. 1978) surveys of the sky for X-ray emission has resulted in many proposed identifications with individual galaxies and clusters of galaxies. The X-ray positions are not usually accurate enough to enable a positive identification to be made of the X-ray sources with optical or radio objects, and hence the identification is often based on statistical arguments — viz., the unexpected occurrence of unusual galaxies, radio sources or clusters of galaxies within or near the X-ray error boxes. There is usually no significant information available on the angular size of the X-ray emitter but in two or three cases (e.g. Perseus cluster, Coma cluster and Virgo cluster) the angular resolution is good enough to identify a broad component with dimensions approaching those of the whole cluster. This extended X-ray emission has been ascribed to either inverse Compton scattering of the 3° microwave background by relativistic electrons in the intra-cluster medium or to thermal-bremsstrahlung emission by an optically thin plasma at - 10s K.

scholarly journals Bremsstrahlung soft X-ray emission from clusters heated by a Gaussian laser beam

2013 ◽  
Vol 32 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Manoj Kumar ◽  
Rohtash Singh ◽  
Updesh Verma
Keyword(s):  
Plasma Frequency ◽  
Short Pulse ◽  
Hydrodynamic Pressure ◽  
Laser Frequency ◽  
Plasma Resonance ◽  
X Rays ◽  
Gaussian Laser Beam ◽  
X Ray ◽  
Short Pulse Laser ◽  
Bremsstrahlung Emission

AbstractA theoretical model of soft X-ray emission from laser irradiated clusters is developed. An intense short pulse laser of Gaussian radial and temporal profiles impinged on a clustered gas jet, heats the cluster electrons, leading to Bremsstrahlung emission of X-rays. As the clusters expand under hydrodynamic pressure, plasma frequency of the cluster electrons ωpedecreases. When plasma frequency of a cluster approaches plasma resonance${\rm \omega}_{\,pe} = \sqrt{3} {\rm \omega}$(where ω is the laser frequency), the electrons are resonantly heated by the laser and a rapid rise in X-ray emission occurs. After a while, when cluster expansion detunes the plasma resonance, X-ray emission falls off.

scholarly journals The Optical/UV Excess of X-Ray-dim Isolated Neutron Stars. I. Bremsstrahlung Emission from a Strangeon Star Atmosphere

2017 ◽  
Vol 837 (1) ◽  
pp. 81 ◽  
Author(s):  
Weiyang Wang ◽  
Jiguang Lu ◽  
Hao Tong ◽  
Mingyu Ge ◽  
Zhaosheng Li ◽  
...  
Keyword(s):  
Neutron Stars ◽  
X Ray ◽  
Bremsstrahlung Emission ◽  
Uv Excess

Angular Distribution and Polarization of the Continuum Emission in Plasmas with Toroidal Symmetry

1988 ◽  
Vol 102 ◽  
pp. 223-225
Author(s):  
M. Lamoureux ◽  
J. Jacquet ◽  
R.H. Pratt
Keyword(s):  
Monte Carlo ◽  
Radiative Recombination ◽  
Distribution Functions ◽  
Tokamak Plasma ◽  
Degree Of Polarization ◽  
Continuum Emission ◽  
Monte Carlo Code ◽  
Superthermal Electrons ◽  
X Ray ◽  
The Continuum

AbstractSuperthermal electrons in plasmas are usually strongly directional, and this confers angular dependence and polarization to the X-ray continuum radiation emitted. Here, we give the relations between the anisotropic distribution functions f(v,θ) and the degree of polarization of the emission due to direct radiative recombination and bremsstrahlung. An application is then made to a tokamak plasma whose f(v,θ) we obtained from a Monte Carlo code.

scholarly journals Return Current Instability in Flares

1989 ◽  
Vol 104 (2) ◽  
pp. 313-316
Author(s):  
D. Cromwell ◽  
P. McQuillan ◽  
J.C. Brown
Keyword(s):  
Solar Flares ◽  
Small Area ◽  
Thick Target ◽  
Target Electron ◽  
Return Current ◽  
Ion Acoustic Wave ◽  
X Ray ◽  
Acoustic Wave Generation ◽  
Bremsstrahlung Emission ◽  
Current Instability

AbstractWe consider the problem of ion-acoustic wave generation, and resultant anomalous Joule heating, by a return current driven unstable by a small-area thick-target electron beam in solar flares. We find that, contrary to the usual assumption, the hard X-ray bremsstrahlung emission may actually be enhanced in comparison to conventional thick-target models. This present paper is a summary of the work of Cromwell, McQuillan and Brown (1988).

The Superthermal Electrons in Flare Loops

1994 ◽  
Vol 144 ◽  
pp. 235-242
Author(s):  
M. Karlický
Keyword(s):  
Solar Atmosphere ◽  
Particle Interaction ◽  
Electron Bombardment ◽  
Atmospheric Response ◽  
Evaporation Process ◽  
Superthermal Electrons ◽  
Return Current ◽  
Wave Particle Interaction ◽  
X Ray ◽  
Flare Loops

AbstractIn this paper the collisional, return current, mirroring and wave-particle interaction effects on the propagation of superthermal electrons in flare loops are reviewed. Moreover, the electron bombardment of dense layers of the solar atmosphere and corresponding atmospheric response are presented. The accompanied X-ray, radio and Hαemissions during the evaporation process are discussed.

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