X-ray and Magnetic Features of Hα Surges

1996 ◽  
pp. 437-438 ◽  
Author(s):  
A. Okubo ◽  
R. Matsumoto ◽  
S. Miyaji ◽  
M. Akioka ◽  
H. Zhang ◽  
...  
Keyword(s):  
X Ray ◽  
Magnetic Features

scholarly journals Structural and Magnetic Properties of FePd Thin Film Synthesized by Electrodeposition Method

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1454
Author(s):  
Gabriele Barrera ◽  
Federico Scaglione ◽  
Matteo Cialone ◽  
Federica Celegato ◽  
Marco Coïsson ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Magnetic Properties ◽  
Deposition Time ◽  
Magnetic Measurements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fundamental Properties ◽  
Magnetic Features ◽  
Application Fields

Bimetallic nanomaterials in the form of thin film constituted by magnetic and noble elements show promising properties in different application fields such as catalysts and magnetic driven applications. In order to tailor the chemical and physical properties of these alloys to meet the applications requirements, it is of great importance scientific interest to study the interplay between properties and morphology, surface properties, microstructure, spatial confinement and magnetic features. In this manuscript, FePd thin films are prepared by electrodeposition which is a versatile and widely used technique. Compositional, morphological, surface and magnetic properties are described as a function of deposition time (i.e., film thickness). Chemical etching in hydrochloric acid was used to enhance the surface roughness and help decoupling crystalline grains with direct consequences on to the magnetic properties. X-ray diffraction, SEM/AFM images, contact angle and magnetic measurements have been carried out with the aim of providing a comprehensive characterisation of the fundamental properties of these bimetallic thin films.

EFFECT OF AIR EXPOSURE ON STRUCTURAL AND MAGNETIC FEATURES OF FeCo NANOPARTICLES

2007 ◽  
Vol 21 (18) ◽  
pp. 1161-1168 ◽  
Author(s):  
S. MOURDIKOUDIS ◽  
K. SIMEONIDIS ◽  
M. ANGELAKERIS ◽  
I. TSIAOUSSIS ◽  
O. KALOGIROU ◽  
...  
Keyword(s):  
Organometallic Complexes ◽  
Soft Magnetic ◽  
Air Exposure ◽  
X Ray ◽  
First Case ◽  
High Metal ◽  
Magnetic Nanomaterial ◽  
Magnetic Features ◽  
Structural And Magnetic Properties ◽  
Feco Nanoparticles

Monodisperse FeCo nanoparticles were synthesized via thermal decomposition of appropriate organometallic complexes in heated toluene containing surfactants, aiming to a soft magnetic nanomaterial with a high metal percent. The particles were characterized by X-ray powder diffraction, electron microscopy, and static magnetometry techniques. The effect of air exposure on the structural and magnetic properties was examined. Portions of the dried nanoparticles were mixed with additional surfactants or polyvinylpyrrolidone, followed by redispersion into tetrahydrofuran, so as to study arrangement features in the first case, while the use of polyvinylpyrrolidone intended to the expansion of the interparticle distances in order to get more "isolated" nanoparticles.

The correspondence between x-ray bright points and evolving magnetic features in the quiet sun

Solar Physics ◽  
1993 ◽  
Vol 144 (1) ◽  
pp. 15-35 ◽  
Author(s):  
D. F. Webb ◽  
S. F. Martin ◽  
D. Moses ◽  
J. W. Harvey
Keyword(s):  
X Ray ◽  
Quiet Sun ◽  
Magnetic Features

scholarly journals Reproducibility and Scalability of Magnetic Nanoheater Synthesis

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2059
Author(s):  
Jesus G. Ovejero ◽  
Alvaro Gallo-Cordova ◽  
Alejandro G. Roca ◽  
M. P. Morales ◽  
Sabino Veintemillas-Verdaguer
Keyword(s):  
High Temperature ◽  
Strong Dependence ◽  
General Rule ◽  
Magnetic Hyperthermia ◽  
Organic Media ◽  
Intrinsic Variability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Colloidal Crystallization ◽  
Magnetic Features

The application of magnetic nanoparticles requires large amounts of materials of reproducible quality. This work explores the scaled-up synthesis of multi-core iron oxide nanoparticles through the use of thermal decomposition in organic media and kilograms of reagents. To this end, we check the effect of extending the high temperature step from minutes to hours. To address the intrinsic variability of the colloidal crystallization nucleation process, the experiments were repeated and analyzed statistically. Due to the simultaneity of the nuclei growth and agglomeration steps, the nanostructure of the samples produced was a combination of single- and multi-core nanoparticles. The main characteristics of the materials obtained, as well as the reaction yields, were analyzed and compared. As a general rule, yield, particle size, and reproducibility increase when the time at high temperature is prolonged. The samples obtained were ranked in terms of the reproducibility of different structural, colloidal, and magnetic features. The capability of the obtained materials to act as nanoheaters in magnetic hyperthermia was assessed, showing a strong dependence on the crystallite size (calculated by X-ray diffraction), reflecting the nanoparticle volume with a coherent magnetization reversal.

scholarly journals Coronal Bright Points

1976 ◽  
Vol 71 ◽  
pp. 145-146
Author(s):  
L. Golub ◽  
A. S. Krieger ◽  
G. S. Vaiana
Keyword(s):  
Magnetic Flux ◽  
Transition Region ◽  
Solar Surface ◽  
Active Regions ◽  
Bright Point ◽  
X Ray ◽  
Coronal Bright Points ◽  
Mean Lifetime ◽  
Magnetic Features

Soft X-ray images of the inner corona obtained with the AS&E spectrograph telescope aboard Skylab revealed the presence of coronal bright points in far greater numbers than had previously been suspected. Bright points are associated with bipolar magnetic features with typical diameters of 1–2 × 104 km, mean lifetime of eight hours and magnetic flux 1019–1020 Mx. Several thousand bright points emerge over the solar surface per day, thereby bringing up more magnetic flux than is contributed by the larger active regions during the period of observation, May 1973 to February 1974. Bright points identified in X-ray photographs are seen as small (5–10″) emission features in ground-based Hα and Ca K spectroheliograms as well as in transition region lines observed in other Skylab instruments. Typical bright point temperatures are 1.5–2 × 106 K and typical densities are ∼ 5 × 109 cm−3.

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.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

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