scholarly journals Different modes of runaway electron beams generated in high-pressure gases

2021 ◽  
Vol 2064 (1) ◽  
pp. 012001
Author(s):  
V F Tarasenko ◽  
D A Sorokin ◽  
D V Beloplotov ◽  
M I Lomaev ◽  
E Kh Baksht ◽  
...  
Keyword(s):  
High Pressure ◽  
Runaway Electron ◽  
Experimental Studies ◽  
Beam Current ◽  
Current Amplitude ◽  
X Rays ◽  
X Ray ◽  
Beam Current Amplitude ◽  
The One ◽  
Direction Opposite

Abstract This article presents the results of experimental studies of different modes of a runaway electron beam (RAEB) generation in high-pressure gases as well as X-rays caused by it. In particular, the mode with the greatest beam current amplitude, the one with two current pulses, that with the X-ray pulse duration of 100s ns, the mode in which a RAEB propagates in the direction opposite from an anode, and some others are described. The effect of the cathode design and material on the RAEB current amplitude and duration in atmospheric-pressure air is shown. When analyzing the most common modes, the features of the gap breakdown are used.

scholarly journals Stellar Winds in Massive X-ray Binaries

2016 ◽  
Vol 12 (S329) ◽  
pp. 355-358
Author(s):  
Peter Kretschmar ◽  
Silvia Martínez-Núñez ◽  
Enrico Bozzo ◽  
Lidia M. Oskinova ◽  
Joachim Puls ◽  
...  
Keyword(s):  
Compact Object ◽  
High Mass ◽  
Stellar Winds ◽  
X Rays ◽  
X Ray ◽  
Current State ◽  
Wide Range ◽  
Strong Winds ◽  
The One ◽  
X Ray Binaries

AbstractStrong winds from massive stars are a topic of interest to a wide range of astrophysical fields. In High-Mass X-ray Binaries the presence of an accreting compact object on the one side allows to infer wind parameters from studies of the varying properties of the emitted X-rays; but on the other side the accretor’s gravity and ionizing radiation can strongly influence the wind flow. Based on a collaborative effort of astronomers both from the stellar wind and the X-ray community, this presentation attempts to review our current state of knowledge and indicate avenues for future progress.

Formation of two crystal modifications of Fe7C3−x at 5.5 GPa

2019 ◽  
Vol 52 (6) ◽  
pp. 1378-1384
Author(s):  
Sergey Gromilov ◽  
Anatoly Chepurov ◽  
Valeri Sonin ◽  
Egor Zhimulev ◽  
Aleksandr Sukhikh ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Experimental Studies ◽  
X Ray Diffraction ◽  
High Iron Content ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Micro Analysis ◽  
Crystal Modifications ◽  
High Pressure Apparatus

The Fe–C system, which is widely used to grow commercial high-pressure–high-temperature diamond monocrystals, is rather complicated due to the formation of carbides. The carbide Fe3C is a normal run product, but the pressure at which Fe7C3 carbide becomes stable is a subject of discussion. This paper demonstrates the synthesis of Fe7C3 carbide and its detailed study using single-crystal and powder X-ray diffraction, as well as electron probe micro-analysis and scanning electron microscopy. The experiments were performed using a multiple-anvil high-pressure apparatus of `split-sphere' (BARS) type at a pressure of 5.5 GPa and a temperature of 1623 K. Our results show that in the Fe–C system, in addition to diamond, a phase that corresponds to the Fe7C3 carbide was synthesized. This means that both carbides (Fe7C3 and Fe3C) are stable at 5.5 GPa. Two crystal phases are described, Fe14C6 and Fe28C12−x . Fe14C6 is based on the well known rhombic structure of Fe7C3, while Fe28C12−x has a different packing order of Fe6C polyhedrons. The results obtained in this study should be taken into account when synthesizing and growing diamond at high pressures and temperatures in metal–carbon systems with a high iron content, as well as when conducting experimental studies on the synthesis of diamond directly from carbide.

Studies of local and intermediate range structure in crystalline and amorphous materials at high pressure using high-energy X-rays

2007 ◽  
Vol 22 (2) ◽  
pp. 108-112 ◽  
Author(s):  
Lars Ehm ◽  
Sytle M. Antao ◽  
Jiuhua Chen ◽  
Darren R. Locke ◽  
F. Marc Michel ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Atomic Structure ◽  
Amorphous Materials ◽  
High Energy ◽  
Liquid Gallium ◽  
X Rays ◽  
X Ray ◽  
X Ray Scattering ◽  
Current State

The method of high-energy total elastic X-ray scattering to determine the atomic structure of nanocrystalline, highly disordered, and amorphous materials is presented. The current state of the technique, its potential, and limitations are discussed with two successful studies on the pressure induced phase transition in mackinawite (FeS) and the high-pressure behavior of liquid gallium.

The Hunt for Hydrogen in the High-Pressure Phase of Ca(OH)2 and Ca(OD)2: Neutrons Versus X-Rays

2004 ◽  
Vol 443-444 ◽  
pp. 341-344
Author(s):  
Robert J. Papoular ◽  
Martin Kunz
Keyword(s):  
High Pressure ◽  
High Pressure Phase ◽  
Recent Measurement ◽  
X Rays ◽  
Neutron Data ◽  
Neutron Measurement ◽  
X Ray ◽  
The Us ◽  
Deuterated Sample ◽  
Pressure Phase

A recent measurement on the high-pressure phase of Ca(OH)2using high-resolution synchrotron X-ray powder diffraction has been carried out on a hydrogenated sample at high-temperature. It complements an earlier time-of-flight neutron measurement carried out in the US on a deuterated sample at low temperature. The two protons are found by Rietveld refinement using a new suitable non-Fourier based strategy, for which GSAS and FullProf yield very similar results. Our X-ray result agrees with the previous neutron study for one proton site only, prompting us to reinvestigate the neutron data. A second new and distinct non Fourier-based strategy coupled with GSAS is used to tackle the latter data and indeed confirms the US results. Whilst the reasons for this X-Ray vs Neutron discrepancy can only be guessed at this stage, the use of the two related proton-finding strategies could be extended beyond our specific study.

scholarly journals Deep Learning Models for Pneumonia Identification and Classification Based on X-Ray Images

2021 ◽  
Vol 38 (3) ◽  
pp. 903-909
Author(s):  
Veeranjaneyulu Naralasetti ◽  
Reshmi Khadherbhi Shaik ◽  
Gayatri Katepalli ◽  
Jyostna Devi Bodapati
Keyword(s):  
Experimental Studies ◽  
Cross Entropy ◽  
X Rays ◽  
Weight Decay ◽  
X Ray ◽  
Proposed Model ◽  
Benchmark Datasets ◽  
Classification Tasks ◽  
Multi Class Classification ◽  
Fully Connected

Diagnosis based on chest X-rays is widely used and approved for the diagnosis of various diseases such as Pneumonia. Manually screening of theses X-ray images technician or radiologist involves expertise and time consuming. Addressing this, we propose an automated approach for the diagnosis of pneumonia by assisting doctors in spotting infected areas in the X-ray images. We propose a deep Convolutional Neural Network (CNN) model for efficiently detecting the presence of pneumonia in the X-ray images. The proposed CNN is designed with 5 convolution blocks followed by 4 fully connected layers. In order to boost the performance of the model, we incorporate batch normalization, dynamic dropout, learning rate decay, L2 regularization weight decay along with Adam optimizer and binary Cross-Entropy loss function while training the model using back propagating algorithm. The proposed model is validated on two publicly accessible benchmark datasets, and the experimental studies conducted on these datasets indicate that the proposed model is efficient. The suggested CNN architecture with specified hyper parameters allows the model to outperform several existing models by achieving accuracy of 97.73% and 91.17% respectively for binary and multi-class classification tasks of pneumonia disease.

scholarly journals Measurements of fast electron beams and soft X-ray emission from plasma-focus experiments

Nukleonika ◽  
2016 ◽  
Vol 61 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Władysław Surała ◽  
Marek J. Sadowski ◽  
Roch Kwiatkowski ◽  
Lech Jakubowski ◽  
Jarosław Żebrowski
Keyword(s):  
Plasma Focus ◽  
Fast Electron ◽  
Hot Spots ◽  
Electron Beams ◽  
Experimental Studies ◽  
Neutron Counter ◽  
X Rays ◽  
Strong Electron ◽  
Time Resolved ◽  
X Ray

Abstract The paper reports results of the recent experimental studies of pulsed electron beams and soft X-rays in plasma-focus (PF) experiments carried out within a modified PF-360U facility at the NCBJ, Poland. Particular attention was focused on time-resolved measurements of the fast electron beams by means of two different magnetic analyzers, which could record electrons of energy ranging from about 41 keV to about 715 keV in several (6 or 8) measuring channels. For discharges performed with the pure deuterium filling, many strong electron signals were recorded in all the measuring channels. Those signals were well correlated with the first hard X-ray pulse detected by an external scintillation neutron-counter. In some of the analyzer channels, electron spikes (lasting about dozens of nanoseconds) and appearing in different instants after the current peculiarity (so-called current dip) were also recorded. For several discharges, fast ion beams, which were emitted along the z-axis and recorded with nuclear track detectors, were also investigated. Those measurements confirmed a multibeam character of the ion emission. The time-integrated soft X-ray images, which were taken side-on by means of a pinhole camera and sensitive X-ray films, showed the appearance of some filamentary structures and so-called hot spots. The application of small amounts of admixtures of different heavy noble gases, i.e. of argon (4.8% volumetric), krypton (1.6% volumetric), or xenon (0.8% volumetric), decreased intensity of the recorded electron beams, but increased intensity of the soft X-ray emission and showed more distinct and numerous hot spots. The recorded electron spikes have been explained as signals produced by quasi-mono-energetic microbeams emitted from tiny sources (probably plasma diodes), which can be formed near the observed hot spots.

Quantitative Determimatioh of Sulfur, Chlorine, Potassium, Calcium, Scandium and Titanium in Aqueous Solutions by Radioisotopic Excited Fluorescent Spectrometer and by Conventional X-Ray Spectrometer

1970 ◽  
Vol 14 ◽  
pp. 102-126 ◽  
Author(s):  
Frank L. Chan ◽  
W. Barclay Jones
Keyword(s):  
Particle Size ◽  
Aqueous Solutions ◽  
Experimental Results ◽  
The Other ◽  
X Rays ◽  
Helium Atmosphere ◽  
X Ray ◽  
Effect Of Particle Size ◽  
The One

AbstractAn x-ray spectrometer with experimental results is herewith described using a radiosotope source Fe55 having a halflife of 2.6 years. As a result of the disintegration, the managanese x-rays are capable of exciting fluorescent x-rays of such elements as sulfur, chlorine, potassium, calcium, scandium and titanium in aqueous solutions. These elements with the Ka wavelengths ranging from 5.3729 Å to 2.7496 Å may be designated as between the very soft x-rays on the one hand and the hard x-rays on the other. The x-ray spectrometer presently described has achieved a resolution of 136 ev, FWHM.Simultaneously, these elements have also been quantitatively determined by conventional x-ray fluorescent spectrometers. Since one of the spectrometers is designed to operate in vacuum as well as in helium or air, determination of sulfur, potassium and calcium were carried out in vacuum. Determination of chlorine was carried out in a helium atmosphere, Calcium, scandium and titanium were determined in air with an air-path spectrometer.In the present study aqueous solutions containing these elements were used. The use of aqueous solutions has the inherent advantages of being homogeneous and free from effect of particle size.

scholarly journals Zur Kenntnis von Ammoniumchrom(III)-fluorid NH4CrF4 / On Ammonium Chromium (III) Fluoride NH4CrF4

1979 ◽  
Vol 34 (7) ◽  
pp. 934-938 ◽  
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
Magnetic Behaviour ◽  
X Rays ◽  
X Ray

Abstract The hitherto unreported compound NH4CrF4 could be prepared by applying hydrothermal high pressure techniques. X-ray powder data show NH4CrF4 to crystallize tetragonally with a = 743.2, c = 650.4 pm, similar to CsFeF4 and other TIAIF4-related structures. The magnetic behaviour was studied below room temperature and proved NH4CrF4 to become antiferromagnetic (TN = 34 K ) within the range known from other AICrF4 compounds. The thermolysis of NH4CrF4, as investigated by X-rays and TG/DTA, begins at about 400 °C and yields CrF3 and also Cr2F5, if extended to 1000 °C

Experimental and Analytical Study of X-Ray Tube Rotor Dynamics

1993 ◽  
Author(s):  
D. A. Nickel ◽  
Charles M. Krousgrill
Keyword(s):  
Acoustic Noise ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Degree Of Freedom ◽  
Response Curves ◽  
Jump Frequency ◽  
Test Fixture ◽  
X Ray ◽  
Response To Change ◽  
The One

Abstract An X-ray tube rotor has been analyzed, using experimental and numerical methods, as a part of an effort to diagnose an intermittent acoustic noise problem. The type of rotor studied is supported by two solid-lubricated angular contact bearings, and operates in a vacuum. Experimental studies of rotor vibration were performed using a test fixture with radio frequency proximity sensors. Coast-down studies indicated the presence of both synchronous and sub-harmonic whirl, along with a tendency for the nature of response to change rapidly during operation. Two ODE (ordinary differential equation) models: a three-dimensional four-degree-of-freedom model and a one-dimensional one-degree-of-freedom model were derived. Large bearing clearances were a significant source of stiffness nonlinearity in both. Direct ODE solution was used to analyze both models. Parametric continuation was also used to find periodic solutions to the one-degree-of-freedom model for different sets of parameter values. The simulations were performed with geometric and stiffness properties representative of the X-ray tube rotor. Small damping was assumed because of the solid lubricant. Direct ODE solutions showed a variety of synchronous and subharmonic periodic motions. Multi-branch frequency response curves were computed using continuation. Qualitative agreement between experimental and numerical results was obtained in terms of tendency to jump, frequency at which multivaluedness was first observed, and existence of subharmonic solutions.

scholarly journals Energy transport experiments at Institute of Laser Engineering, Osaka University

1989 ◽  
Vol 7 (3) ◽  
pp. 495-504 ◽  
Author(s):  
K. A. Tanaka ◽  
Y. Kato ◽  
S. Nakai ◽  
H. Shiraga ◽  
T. Yabe ◽  
...  
Keyword(s):  
Energy Transport ◽  
High Efficiency ◽  
Laser Energy ◽  
Rear Side ◽  
X Rays ◽  
Uv Laser ◽  
X Ray ◽  
Characteristic Emission ◽  
Irradiation Energy ◽  
The One

Emissions from the rear side of the targets were temporally resolved by irradiating an ultraviolet (UV) laser on Al and Au thin targets. A difference was clearly observed between the above two targets. Given the fact that absorbed laser energy is converted with a very high efficiency to soft x-rays in a high Z plasma, a characteristic emission peak only observed for Au targets was attributed to the effect of soft x-ray energy transport. The ablation pressures estimated from the emissions indicate that the pressure scaling for Au is close to the one by x-ray radiation rather than by a UV laser. With soft x-ray irradiation, energy transport in A1 foils was also studied. An ablation pressure was estimated by the shock speed.

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