Spectroscopy of high-temperature solar flare plasmas

1991 ◽  
Vol 336 (1643) ◽  
pp. 461-470 ◽  
Keyword(s):  
High Temperature ◽  
X Rays ◽  
Temperature Plasma ◽  
Flux Tubes ◽  
X Ray ◽  
Element Abundances ◽  
The Past ◽  
Hot Plasma ◽  
Wide Range ◽  
Flare Process

The past decade has seen great improvements in the quality of X -ray spectra of solar flares obtained from spacecraft. Such spectra show lines emitted by highly ionized atoms of abundant elements which make up high-temperature plasma contained within coronal magnetic flux tubes. This plasma is probably energized at or a little before the flare impulsive stage, as revealed by bursts of hard X-rays. Temperature and density conditions can be deduced from ratios of line intensities, as well as element abundances under certain conditions. In this paper, several examples of line ratios to deduce these are given. Analysis shows that there is a wide range of electron temperatures - generally from 2 x 10 6 K to 20 x 10 6 K - though sometimes even higher. Electron densities of around 10 17 -10 18 m -3 have been derived, higher values occurring at the flare peak or just before, and then declining. The physical conditions of the hot plasma are now precisely enough known from X -ray spectroscopy that models of flares which have been constructed in the past can be constrained. The most profitable direction for research in this area in the near future would in fact appear to be for a much better linking of the findings from X -ray spectra and modelling of plasma in flux tubes to understand better the flare process in general.

X-Ray Emission from High-Temperature Laboratory, Plasmas

1974 ◽  
Vol 18 ◽  
pp. 1-25
Author(s):  
D. J. Nagel
Keyword(s):  
Power Generation ◽  
High Temperature ◽  
Diagnostic Information ◽  
X Rays ◽  
Temperature Plasma ◽  
Fusion Power ◽  
X Ray ◽  
High Temperature Plasma ◽  
Laboratory Plasmas

AbstractThe radiation from plasmas hotter than 106K falls in the x-ray region. Such plasmas are required for fusion power generation. They can also be used as x-ray sources. Measurements of x-ray emission from high temperature plasma yields (a) diagnostic information on the plasma conditions and (b) the characteristics of plasma x-ray sources which determine their applications. Hence, measurements of x-rays from plasmas are finding widespread use.

scholarly journals Atomic constants deduced from secondary cathode ray measurements

1933 ◽  
Vol 143 (848) ◽  
pp. 48-60 ◽  
Keyword(s):  
Magnetic Fields ◽  
X Rays ◽  
X Ray ◽  
The Past ◽  
Wide Range

1. It is well known that the accurate measurement of the energies of the secondary cathode rays excited by homogeneous X-rays can yield results capable of supplementing our knowledge of the most probable values of the fundamental atomic constants. this application of the "magnetic spectrograph" has already been discussed by one of us in some detail, and kretschmar has published an account of accurate measurements on X-ray electrons, from which he has deduced very consistent values of e / m 0 . In this work Kretschmar used molybdenum K radiations, and produced his magnetic fields by a large solenoid. 2. We have during the past fifteen months photographed a large number of secondary cathode-ray spectra, using cooper K as primary X radiation. For a few elements, for which the results will be detailed later in this paper, we have made very careful measurements of the energies, cross-checking the observations by working in a wide range magnetic fields.

scholarly journals Thermal and Non-Thermal X-Rays from SN 1006 and IC 443

1998 ◽  
Vol 188 ◽  
pp. 256-257
Author(s):  
M. Ozaki ◽  
K. Koyama
Keyword(s):  
High Temperature ◽  
Supernova Remnants ◽  
Recent Observation ◽  
X Rays ◽  
Temperature Plasma ◽  
Hard Component ◽  
X Ray ◽  
High Temperature Plasma ◽  
Thermal Origin ◽  
Non Equilibrium

From many Galactic supernova remnants (SNRs), X-ray emissions consisting of non-equilibrium ionization (NEI) plasma and additional hard component are detected. The hard emission have been usually interpreted as a high temperature plasma of = 10 keV. However, the recent observation with ASCA made it clear that the hard components of some SNRs are of non-thermal origin. Here we report the ASCA results of SN 1006 and IC 443 observations as an example of such SNRs.

scholarly journals Hot Plasma in the Galaxy

1998 ◽  
Vol 188 ◽  
pp. 47-50
Author(s):  
S. Yamauchi
Keyword(s):  
Galactic Plane ◽  
Point Sources ◽  
X Rays ◽  
Temperature Plasma ◽  
X Ray ◽  
X Ray Imaging ◽  
Hot Plasma ◽  
The Galaxy ◽  
Bulge Region ◽  
Imaging And Spectroscopy

In the X-ray band, we can see weak and extended X-rays along the Galactic plane and near the Galactic Bulge region, although these regions are dominated by many point sources (e.g., Warwick et al. 1985). The Tenma satellite discovered conspicuous emission lines from selected regions near the Galactic plane (Koyama et al. 1986). These lines are identified with K-shell line from He-like Fe, hence the extended emission is attributable to optically thin hot plasmas with temperatures of several keV. The origin of the thin hot plasmas, however, have been debatable, because no class of X-ray objects shows such high temperature plasma emissions. To investigate the origin of the extended X-rays, we are currently observing the Galactic plane regions with the ASCA satellite. In this paper, we report on the ASCA results: the hard X-ray imaging and spectroscopy of the hot plasma in the Galaxy.

Opacity of Krypton X-ray lines in high-temperature plasma implosion

2019 ◽  
Vol 33 (33) ◽  
pp. 1950418
Author(s):  
Zhiqiang Zhen ◽  
Jian He
Keyword(s):  
High Temperature ◽  
Line Ratio ◽  
Text Line ◽  
X Rays ◽  
Temperature Plasma ◽  
X Ray ◽  
High Temperature Plasma ◽  
Gaussian Profile ◽  
Density Diagnostics ◽  
Escape Factor

For accurate electron temperature and density diagnostics in laser high-temperature plasma implosion, opacity of Krypton (Kr) helium-[Formula: see text] and Balmer-[Formula: see text] lines are discussed, and ratio of escape factor of the two X-rays are calculated, both for Gaussian and Holtzmarkian profiles. Finally, the line ratios of the two X-ray lines are analyzed for optically thin and thick plasmas. Results indicate that for the Gaussian profile, the line ratio varies greatly with the opacity of the Kr helium-[Formula: see text] line, which provides excellent source for temperature and electron density diagnostics; while for the Holtzmarkian profile, the line ratio varies less with the opacity of the Kr helium-[Formula: see text] line, which can be used for escape factor diagnostics. This method is significant in accurate plasma diagnostics using X-rays under the condition of optically thick.

Low Voltage Biological X-Ray Microanalysis: Progress and a Remaining Problem

2000 ◽  
Vol 6 (S2) ◽  
pp. 758-759
Author(s):  
Patrick Echlin
Keyword(s):  
Low Voltage ◽  
Light Element ◽  
Primary Electron ◽  
X Rays ◽  
Element Analysis ◽  
X Ray ◽  
Analytical Technique ◽  
The Past ◽  
Beam Sample ◽  
Wide Range

Experimental work in a number of research groups over the past five years have demonstrated, unequivocally, that low voltage i.e. 5kV and below, quantitative x-ray microanalysis is a valid analytical technique which can be applied to a wide range of specimens. The advantages of this approach are now generally well known and include improved image contrast, diminished bulk charging of the sample and for bulk specimens, a reduction in the size of the beam-sample interactive volume from which the x-rays are generated, and as a consequence, a considerable improvement in the microanalytical spatial resolution. In addition, low voltages ensure a sensitive surface analysis procedure which provides true topographic contrast and that in the case of light element analysis, quantitation is simplified because the atomic number (Z), absorption (A) and fluorescence (F) effects are minimised. All these advantages are improved further if one uses a field emission gun as the primary electron source.

scholarly journals On Two Mechanisms of X-Ray Generation in Comets

1985 ◽  
Vol 85 ◽  
pp. 365-368
Author(s):  
S. Ibadov
Keyword(s):  
High Temperature ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Interplanetary Dust Particles ◽  
Temperature Plasma ◽  
X Ray ◽  
Plasma Generation ◽  
High Temperature Plasma

AbstractThe intensity of solar X-radiation scattered by a comet is calculated and compared to the proper X-radiation of the comet due to impacts of cometary and interplanetary dust particles. Detection of X-radiation of dusty comets at small heliocentric distances (R ≤ 1 a.u.) is found to be an indicator of high-temperature plasma generation as result of grain collisions.

scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A18 ◽  
Author(s):  
C. H. A. Logan ◽  
B. J. Maughan ◽  
M. N. Bremer ◽  
P. Giles ◽  
M. Birkinshaw ◽  
...  
Keyword(s):  
Angular Resolution ◽  
False Positive Rate ◽  
High Sensitivity ◽  
Point Sources ◽  
Selection Function ◽  
X Rays ◽  
Cluster Emission ◽  
X Ray ◽  
Wide Range ◽  
Function Modelling

Context. The XMM-XXL survey has used observations from the XMM-Newton observatory to detect clusters of galaxies over a wide range in mass and redshift. The moderate PSF (FWHM ~ 6″ on-axis) of XMM-Newton means that point sources within or projected onto a cluster may not be separated from the cluster emission, leading to enhanced luminosities and affecting the selection function of the cluster survey. Aims. We present the results of short Chandra observations of 21 galaxy clusters and cluster candidates at redshifts z > 1 detected in the XMM-XXL survey in X-rays or selected in the optical and infra-red. Methods. With the superior angular resolution of Chandra, we investigate whether there are any point sources within the cluster region that were not detected by the XMM-XXL analysis pipeline, and whether any point sources were misclassified as distant clusters. Results. Of the 14 X-ray selected clusters, 9 are free from significant point source contamination, either having no previously unresolved sources detected by Chandra or with less than about 10% of the reported XXL cluster flux being resolved into point sources. Of the other five sources, one is significantly contaminated by previously unresolved AGN, and four appear to be AGN misclassified as clusters. All but one of these cases are in the subset of less secure X-ray selected cluster detections and the false positive rate is consistent with that expected from the XXL selection function modelling. We also considered a further seven optically selected cluster candidates associated with faint XXL sources that were not classed as clusters. Of these, three were shown to be AGN by Chandra, one is a cluster whose XXL survey flux was highly contaminated by unresolved AGN, while three appear to be uncontaminated clusters. By decontaminating and vetting these distant clusters, we provide a pure sample of clusters at redshift z > 1 for deeper follow-up observations, and demonstrate the utility of using Chandra snapshots to test for AGN in surveys with high sensitivity but poor angular resolution.

A multi-length-scale USAXS/SAXS facility: 10–50 keV small-angle X-ray scattering instrument

2013 ◽  
Vol 46 (5) ◽  
pp. 1508-1512 ◽  
Author(s):  
Byron Freelon ◽  
Kamlesh Suthar ◽  
Jan Ilavsky
Keyword(s):  
Small Angle ◽  
Soft Matter ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
X Ray Scattering ◽  
Wide Range ◽  
And Performance ◽  
New Facility ◽  
Ray Scattering

Coupling small-angle X-ray scattering (SAXS) and ultra-small-angle X-ray scattering (USAXS) provides a powerful system of techniques for determining the structural organization of nanostructured materials that exhibit a wide range of characteristic length scales. A new facility that combines high-energy (HE) SAXS and USAXS has been developed at the Advanced Photon Source (APS). The application of X-rays across a range of energies, from 10 to 50 keV, offers opportunities to probe structural behavior at the nano- and microscale. An X-ray setup that can characterize both soft matter or hard matter and high-Zsamples in the solid or solution forms is described. Recent upgrades to the Sector 15ID beamline allow an extension of the X-ray energy range and improved beam intensity. The function and performance of the dedicated USAXS/HE-SAXS ChemMatCARS-APS facility is described.

scholarly journals Two-temperature magnetohydrodynamic simulations for sub-relativistic active galactic nucleus jets: dependence on the fraction of the electron heating

2020 ◽  
Vol 493 (4) ◽  
pp. 5761-5772 ◽  
Author(s):  
Takumi Ohmura ◽  
Mami Machida ◽  
Kenji Nakamura ◽  
Yuki Kudoh ◽  
Ryoji Matsumoto
Keyword(s):  
Electron Temperature ◽  
X Rays ◽  
Ion Temperature ◽  
Temperature Plasma ◽  
Electron Heating ◽  
Coulomb Collisions ◽  
X Ray ◽  
Jet Plasma ◽  
Magnetohydrodynamic Simulations ◽  
Two Temperature

ABSTRACT We present the results of two-temperature magnetohydrodynamic simulations of the propagation of sub-relativistic jets of active galactic nuclei. The dependence of the electron and ion temperature distributions on the fraction of electron heating, fe, at the shock front is studied for fe = 0, 0.05, and 0.2. Numerical results indicate that in sub-relativistic, rarefied jets, the jet plasma crossing the terminal shock forms a hot, two-temperature plasma in which the ion temperature is higher than the electron temperature. The two-temperature plasma expands and forms a backflow referred to as a cocoon, in which the ion temperature remains higher than the electron temperature for longer than 100 Myr. Electrons in the cocoon are continuously heated by ions through Coulomb collisions, and the electron temperature thus remains at Te > 109 K in the cocoon. X-ray emissions from the cocoon are weak because the electron number density is low. Meanwhile, X-rays are emitted from the shocked intracluster medium (ICM) surrounding the cocoon. Mixing of the jet plasma and the shocked ICM through the Kelvin–Helmholtz instability at the interface enhances X-ray emissions around the contact discontinuity between the cocoon and shocked ICM.

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