scholarly journals The Spatial and Temporal Variations of Turbulence in a Solar Flare

2021 ◽  
Vol 923 (1) ◽  
pp. 40
Author(s):  
Morgan Stores ◽  
Natasha L. S. Jeffrey ◽  
Eduard P. Kontar
Keyword(s):  
Kinetic Energy ◽  
Temporal Variations ◽  
Vital Role ◽  
Spectral Lines ◽  
Kinetic Energy Density ◽  
X Rays ◽  
Imaging Spectrometer ◽  
X Ray ◽  
Density Maps ◽  
Spectral Profiles

Abstract Magnetohydrodynamic plasma turbulence is believed to play a vital role in the production of energetic electrons during solar flares, and the nonthermal broadening of spectral lines is a key sign of this turbulence. Here, we determine how flare turbulence evolves in time and space using spectral profiles of Fe xxiv, Fe xxiii, and Fe xvi, observed by the Hinode/EUV Imaging Spectrometer. Maps of nonthermal velocity are created for times covering the X-ray rise, peak, and decay. For the first time, the creation of kinetic energy density maps reveal where energy is available for energization, suggesting that similar levels of energy may be available to heat and/or accelerate electrons in large regions of the flare. We find that turbulence is distributed throughout the entire flare, often greatest in the coronal loop tops, and decaying at different rates at different locations. For hotter ions (Fe xxiv and Fe xxiii), the nonthermal velocity decreases as the flare evolves and during/after the X-ray peak shows a clear spatial variation decreasing linearly from the loop apex toward the ribbon. For the cooler ion (Fe xvi), the nonthermal velocity remains relativity constant throughout the flare, but steeply increases in one region corresponding to the southern ribbon, peaking just prior to the peak in hard X-rays before declining. The results suggest turbulence has a more complex temporal and spatial structure than previously assumed, while newly introduced turbulent kinetic energy maps show the availability of the energy and identify important spatial inhomogeneities in the macroscopic plasma motions leading to turbulence.

scholarly journals X-Ray Aspects of the IRAS Galaxies

1998 ◽  
Vol 188 ◽  
pp. 145-148
Author(s):  
E.J.A. Meurs
Keyword(s):  
Stellar Evolution ◽  
Seyfert Galaxies ◽  
Temporal Variations ◽  
Spectral Studies ◽  
X Rays ◽  
X Ray ◽  
Active Core

Several IRAS galaxies have been detected at X-rays, with a variety of satellite observatories. About half of these are classified optically as Seyfert galaxies. Among those not (convincingly) classified as AGN, many have X-ray luminosities for which stellar evolution products offer convenient explanations. Some non-active IRAS galaxies display anomalously high levels of X-ray emission for which several conceivable origins are investigated: optical misclassification, X-ray misidentification, hidden AGN, incidental activity, starburst, environmental sources. X-ray spectral studies and temporal variations constitute important tools for further investigation, for instance to assess the strength of a starburst or to establish signatures of an active core.

Microanalytical studies (X-ray photoelectron spectrometry) of surface hydration reactions of cement compounds

1983 ◽  
Vol 310 (1511) ◽  
pp. 85-92 ◽  
Keyword(s):  
Blast Furnace ◽  
Chemical Composition ◽  
Kinetic Energy ◽  
Blast Furnace Slag ◽  
X Rays ◽  
Hydration Time ◽  
X Ray ◽  
Tentative Interpretation ◽  
Furnace Slag ◽  
Cement Compounds

X-ray photoelectron spectrometry (X.p.s.) measures the kinetic energy of electrons photoejected from a solid surface by soft X-rays. The kinetic energy of the photoelectrons can be related to the binding energy that these electrons had originally in the solid. X.p.s. is a rather new technique for studying cements. It has been used recently in the surface analysis of C 3 S, C 2 S, C 3 A and blast-furnace slag grains during their hydration. Changes in chemical composition have been found as soon as the surface comes into contact with water, shown by a change in the shape, position an intensity of characteristic peaks like Ca 2p , Si 2p , O l8 and a reduction of characteristic ratios Ca/Si or Al/Si. A tentative interpretation of X.p.s. kinetic curves as a function of hydration time is presented.

scholarly journals Photoreduction and validation of haem–ligand intermediate states in protein crystals byin situsingle-crystal spectroscopy and diffraction

IUCrJ ◽  
2017 ◽  
Vol 4 (3) ◽  
pp. 263-270 ◽  
Author(s):  
Demet Kekilli ◽  
Tadeo Moreno-Chicano ◽  
Amanda K. Chaplin ◽  
Sam Horrell ◽  
Florian S. N. Dworkowski ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Structural Data ◽  
X Rays ◽  
Solvated Electrons ◽  
X Ray ◽  
Redox States ◽  
Density Maps ◽  
Correct Assignment ◽  
Wide Range

Powerful synergies are available from the combination of multiple methods to study proteins in the crystalline form. Spectroscopies which probe the same region of the crystal from which X-ray crystal structures are determined can give insights into redox, ligand and spin states to complement the information gained from the electron-density maps. The correct assignment of crystal structures to the correct protein redox and ligand states is essential to avoid the misinterpretation of structural data. This is a particular concern for haem proteins, which can occupy a wide range of redox states and are exquisitely sensitive to becoming reduced by solvated electrons generated from interactions of X-rays with water molecules in the crystal. Here, single-crystal spectroscopic fingerprinting has been applied to investigate the laser photoreduction of ferric haem in cytochromec′. Furthermore,in situX-ray-driven generation of haem intermediates in crystals of the dye-decolourizing-type peroxidase A (DtpA) fromStreptomyces lividansis described.

An Algorithm for the Description of White and Characteristic Tube Spectra (11 ≤ Z ≤ 83, 10keV ≤ Eo ≤ 50keV)

1991 ◽  
Vol 35 (B) ◽  
pp. 721-726 ◽  
Author(s):  
H. Ebel ◽  
H. Wiederschwinger ◽  
J. Wernisch ◽  
P.A. Pella
Keyword(s):  
Kinetic Energy ◽  
Cross Section ◽  
Atomic Number ◽  
Solid Angle ◽  
Electron Interaction ◽  
X Rays ◽  
X Ray ◽  
The Cross ◽  
Spectral Responses ◽  
The Continuum

Kramers described the cross section of electron interaction with target atoms of atomic number Z bywhere Eo is the kinetic energy of impinging electrons, and E o S) the energy of x-ray photons of the continuum, Smith et al modified this equation, introducing an exponent x, so thatWe applied the cross-section σS, E to the evaluation of experimental results. The evaluation of the measured spectral responses of the x-ray signals nE was performed bywhere f(deff) describes the absorption of x-rays of energy E in the target, RE accounts for backscattering of electrons, DE quantifies the efficiency of x-ray detection within the solid angle Ω.

scholarly journals Simultaneous Observations of Large Enhancement In the Flux of PSR 0950+08 Over a 200 km Baseline at 103 MHz

1996 ◽  
Vol 160 ◽  
pp. 477-478
Author(s):  
A.D. Bobra ◽  
Harish Chandra ◽  
Hari Om Vats ◽  
P. Janardhan ◽  
G.D. Vyas ◽  
...  
Keyword(s):  
Solar Wind ◽  
Interplanetary Medium ◽  
Temporal Variations ◽  
X Rays ◽  
Physical Research Laboratory ◽  
X Ray ◽  
The Earth ◽  
Wind Velocities ◽  
Electro Magnetic ◽  
Galactic Radio

Interplanetary Scintillation (IPS) is a diffraction phenomenon in which coherent electro-magnetic radiation, from a distant radio source, passes through the solar wind, which is a turbulent refracting medium, and suffers scattering. This results in random temporal variations of the signal intensity (scintillation) at the Earth. IPS observations to monitor the interplanetary medium (IPM), to measure solar wind velocities in the directions of a number of compact extra-galactic radio sources and to estimate the angular diameters of their compact components have been carried out for many years at 103 MHz using the IPS facility (Alurkar et al. 1989) of the Physical Research Laboratory (PRL), Ahmedabad, India. Over a period of approximately 10 years of such observations, it has been seen that PSR 0950+08 has always remained well within the noise level. We observed a sudden enhancement in its flux (Deshpande et al. 1994) on 29 July, 1992. The ionospheric observations which are being carried out on a regular basis at PRL using an ionosonde also recorded a steep increase in the absorption index Fmin, which is an indicator of the excess ionization produced due to X-rays. During this period, the Sun was exceptionally quiet, thereby raising the question about the origin of the X-ray flux responsible for the observed steep rise in Fminduring the transit of PSR 0950+08.

Formation of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 257-264
Author(s):  
D Lynden-Bell
Keyword(s):  
Angular Momentum ◽  
Binding Energy ◽  
Kinetic Energy ◽  
Gravitational Potential Energy ◽  
Dimensionless Number ◽  
X Rays ◽  
X Ray ◽  
The Galaxy ◽  
Balmer Lines ◽  
The Relationship

From observations it is deduced that the disk and halo were formed about the same time and that most of the previously gaseous Galaxy became stars then. Dimensional analysis indicates that the flattening of a galaxy is related to its energy,E, angular momentum,H, and mass,M, by the dimensionless number - 2EH2/G5M5. Emphasis is placed on the binding energy, -E, and the energy loss mechanisms of the proto-galaxy, with the aim of explaining Fish's relation -E∝M3/2.Free-bound and free-free emission of hydrogen leads to rapid cooling of proto-galaxies, and dynamical collapse ensues, in which gravitational potential energy is converted into kinetic energy of collapse. As the system becomes flat, this energy is dissipated in violent shocks, behind which zones some 10 to 20 pc thick reach temperatures of 106·5°K and emit strongly in the X-ray region and the ultraviolet. If surrounded by more than a fraction of a gram per cm2, the X-rays will be trapped within the system and eventually converted into Balmer lines, which escape, and Lyman α, which is trapped. About half the total energy of collapse may be left in Lyman α, and it is possible that the system may bounce on this light energy.The readily observed surface brightnesses of galaxies are related to surface densities by the relationship: magnitude 20 per (sec of arc)2= 1·5 gram cm-2, for an assumed mass-to-light ratio of 10.

SOLVING MINERALOGY PROBLEMS WITH THE HELP OF THE “ORIGIN" PACKAGE

2020 ◽  
Vol 386 (4) ◽  
pp. 6-12
Author(s):  
R. T. Abdraimov ◽  
B. E. Vintaykin ◽  
P. A. Saidakhmetov ◽  
N. K. Madiyarov ◽  
M. A. Abdualiyeva
Keyword(s):  
Spectral Analysis ◽  
Fourier Analysis ◽  
Least Squares ◽  
Phase Analysis ◽  
Least Squares Method ◽  
Spectral Lines ◽  
X Rays ◽  
Cauchy Function ◽  
X Ray ◽  
Smoothing Functions

Algorithms for solving typical mineralogical problems associated with quantitative x-ray spectral analysis and quantitative x-ray phase analysis using the program “Origin” are developed. The calculation of the areas and midpoint of spectral lines using the tabular processor of the program “Origin” is considered. Various approaches to determining the parameters of spectral lines using the least squares method using the standard functions of the program “Origin” were tested. The creation of a user function for approximation of diffraction maxima by the Cauchy function taking into account the doublet character of Ka series of x-rays is also considered. Various built-in algorithms for smoothing functions (based on averaging, polynomial approximation and Fourier analysis – synthesis) were tested to find weak diffraction maxima against strong noise; optimal schemes for the application of these algorithms were found. The considered algorithms can be applied in universities when processing the results of laboratory works on the topics "Analysis of spectra of emission of atoms", "Quantitative x-ray spectral analysis" and "Quantitative x-ray phase analysis".

Transient electron density maps from femtosecond x-ray powder diffraction

2014 ◽  
Vol 70 (a1) ◽  
pp. C100-C100
Author(s):  
Vincent Juvé ◽  
Flavio Zamponi ◽  
Marcel Holtz ◽  
Michael Woerner ◽  
Thomas Elsaesser
Keyword(s):  
Charge Transfer ◽  
Electron Density ◽  
Powder Diffraction ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
X Rays ◽  
X Ray ◽  
Density Maps ◽  
Structure Factors ◽  
Diffraction Angle

Ultrashort hard x-ray pulses are sensitive probes of structural dynamics on the picometer length and femtosecond time scales of electronic and atomic motions. Using short hard x-ray pulses as probe in a pump-probe scheme allow to do femtosecond x-ray diffraction experiments [1], which provide transient electron density maps at a femtosecond timescale with a sub-angstrom spatial resolution. In a typical femtosecond x-ray powder diffraction experiment many Debye-Scherrer rings, up to a maximum diffraction angle 2θmax, are recorded for each time delay between the optical pump and the hard x-ray probe. From the diffraction pattern, the change of the diffracted intensity of each rings are monitored. The interference of diffracted x-rays from the many unexcited cells, with known structure factors coming from steady-state measurement, and diffracted x-rays from the few excited cells allows for the detection of the transients structure factors. Problems could arise if the 3D-Fourier transform is directly used because of the abrupt end of the collected information in the reciprocal space (maximum diffraction angle 2θmax). In order to overcome this problem, the Maximum Entropy Method is apply to the data and the transient electron density maps are derived. We apply the femtosecond x-ray powder diffraction technique and the Maximum Entropy Method to study the induced transient polarization by high optical fields on ionic crystals. Such polarizations are connected to a spatial redistribution of electronic charge, which corresponds to a charge transfer between the two ionic compounds [2]. While the charge transfer originates from the anion to the cation in the LiBH and the NaBH4, the LiH exhibits a peculiar behavior: the charge transfer occurs from the cation to the anion. As result from comparison with calculations in the COHSEX framework, this behavior is due to the strong electronic correlations in the LiH [3].

scholarly journals The Spectrometer/Telescope for Imaging X-rays (STIX)

2020 ◽  
Vol 642 ◽  
pp. A15 ◽  
Author(s):  
Säm Krucker ◽  
G. J. Hurford ◽  
O. Grimm ◽  
S. Kögl ◽  
H.-P Gröbelbauer ◽  
...  
Keyword(s):  
Interplanetary Space ◽  
Energy Content ◽  
The Sun ◽  
X Rays ◽  
Imaging Spectrometer ◽  
X Ray ◽  
Nonthermal Electrons ◽  
X Ray Imaging ◽  
Data Volume

Aims. The Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter is a hard X-ray imaging spectrometer, which covers the energy range from 4 to 150 keV. STIX observes hard X-ray bremsstrahlung emissions from solar flares and therefore provides diagnostics of the hottest (⪆10 MK) flare plasma while quantifying the location, spectrum, and energy content of flare-accelerated nonthermal electrons. Methods. To accomplish this, STIX applies an indirect bigrid Fourier imaging technique using a set of tungsten grids (at pitches from 0.038 to 1 mm) in front of 32 coarsely pixelated CdTe detectors to provide information on angular scales from 7 to 180 arcsec with 1 keV energy resolution (at 6 keV). The imaging concept of STIX has intrinsically low telemetry and it is therefore well-suited to the limited resources available to the Solar Orbiter payload. To further reduce the downlinked data volume, STIX data are binned on board into 32 selectable energy bins and dynamically-adjusted time bins with a typical duration of 1 s during flares. Results. Through hard X-ray diagnostics, STIX provides critical information for understanding the acceleration of electrons at the Sun and their transport into interplanetary space and for determining the magnetic connection of Solar Orbiter back to the Sun. In this way, STIX serves to link Solar Orbiter’s remote and in-situ measurements.

was gathered in one stack, it would occupy a space of 1.25 m3, the size of a small office desk. AECL deposited and Nordion deposits radioactive waste material at their Chalk River disposal site. For transport from the supplier to the user (and back to the supplier when most of the source strength is exhausted) ^C o and I37Cs are shipped in special steel casks. These are designed to survive severe traffic accidents, fire, or other disasters. In order to minimize corrosion of cobalt pins or cesium capsules in the irradiation facility, the water of the source storage pool is constantly recirculated through a deionizer. A sensitive radiation monitor close to the deionizer is used to detect any radioactivity in case the water should be contaminated by a leak in the source. Nordion estimated in 1991 that 17 MCi of 60Co was in service worldwide, installed in 170 irradiators in 45 countries. Many of these facilities have been in operation for more than 20 years. They are mostly used for radiation sterilization of medical disposables, and only in some countries are they also used for irradiation of foodstuffs. Details on the design of various types of gamma irradiation facilities can be found in a number of review articles and book chapters ( -). Some of the earliest systematic studies on food irradiation were carried out with x-ray machines. X-rays are produced when matter is bombarded by electrons of sufficiently high kinetic energy. An x-ray tube (Fig. 5) consists basically of an evacuated glass bulb containing a wire filament which can be heated and opposite it a piece of metal, usually tungsten, which can be cooled. The filament is given a negative charge (cathode) and the metal a positive charge (anode, or anticathode). When the cathode filament is heated by passing an electric current through it, it emits electrons. When these hit the anode, x-rays are produced. The anode must be cooled because in a typical x-ray tube about 99% of the energy carried by the electrons may be converted to heat, and only about % appears in the form of

1995 ◽  
pp. 36-37
Keyword(s):  
Kinetic Energy ◽  
Traffic Accidents ◽  
Food Irradiation ◽  
Disposal Site ◽  
Radiation Sterilization ◽  
X Rays ◽  
Source Strength ◽  
X Ray ◽  
Glass Bulb ◽  
High Kinetic Energy
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