scholarly journals On Peculiarities of Betatron Oscillations of Accelerated Electron Bunches in Capillary Waveguides

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Mikhail Veysman
Keyword(s):  
Synchrotron Radiation ◽  
Parametric Excitation ◽  
Electron Bunch ◽  
Short Pulse ◽  
Spectral Parameters ◽  
Electron Bunches ◽  
Narrow Capillary ◽  
Parametric Resonances ◽  
Parametric Instabilities ◽  
The One

It is shown that the dynamics of electrons accelerated in narrow capillary waveguides is significantly influenced by the parametric excitation of their betatron oscillations. On the one hand, this excitation can irreversibly spoil the emittance of an accelerated electron bunch that limits the possibilities of their practical use. On the other hand, controlled parametric excitation of betatron oscillations can be used to generate short-pulse sources of synchrotron radiation. The article analyzes the regions of parametric instabilities, their dependence on the parameters of accelerated electron bunches and guiding structures, and their influence on the dynamics of accelerated electrons. The parameters of the generated synchrotron radiation are also estimated. Measurements of the spectral parameters of synchrotron radiation can serve as a tool for diagnostics of betatron oscillations and their excitation in the case of parametric resonances.

APPLICATION OF A ONE-DIMENSIONAL POSITION SENSITIVE CHAMBER ON SYNCHROTRON RADIATION

2014 ◽  
Vol 27 ◽  
pp. 1460142
Author(s):  
HUIRONG QI ◽  
MEI LIU
Keyword(s):  
Synchrotron Radiation ◽  
Low Cost ◽  
Large Area ◽  
Position Resolution ◽  
One Dimensional ◽  
X Ray ◽  
High Position ◽  
Standard Data ◽  
Wire Chamber ◽  
The One

In the last few years, wire chambers have been frequently used for X-ray detection because of their low cost, large area and reliability. X-ray diffraction is an irreplaceable method for powder crystal lattice measurements. A one-dimensional single-wire chamber has been developed in our lab to provide high position resolution for powder diffraction experiments using synchrotron radiation. There are 200 readout strips of 0.5 mm width with a pitch of 1.0 mm in the X direction, and the working gas is a mixture of Ar and CO2 (90/10). The one-dimensional position of the original ionization point is determined by the adjacent strip's distribution information using the center of gravity method. Recently, a study of the detector's performance and diffraction image was completed at the 1W1B laboratory of the Beijing Synchrotron Radiation Facility (BSRF) using a sample of SiO2. Most of the relative errors between the measured values of diffraction angles and existing data were less than 1%. The best position resolution achieved for the detector in the test was 71 μm (σ value) with a 20 μm slit collimator. Finally, by changing the detector height in incremental distances from the center of the sample, the one-dimensional detector achieved a two-dimensional diffraction imaging function, and the results are in good agreement with standard data.

scholarly journals The Effect of Positive End-Expiratory Pressure on Lung Micromechanics Assessed by Synchrotron Radiation Computed Tomography in an Animal Model of ARDS

2019 ◽  
Vol 8 (8) ◽  
pp. 1117 ◽  
Author(s):  
Gaetano Scaramuzzo ◽  
Ludovic Broche ◽  
Mariangela Pellegrini ◽  
Liisa Porra ◽  
Savino Derosa ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Animal Model ◽  
Acute Respiratory Distress Syndrome ◽  
Synchrotron Radiation ◽  
Gas Phase ◽  
Phase Contrast ◽  
Distress Syndrome ◽  
Regions Of Interest ◽  
Positive End Expiratory Pressure ◽  
The One

Modern ventilatory strategies are based on the assumption that lung terminal airspaces act as isotropic balloons that progressively accommodate gas. Phase contrast synchrotron radiation computed tomography (PCSRCT) has recently challenged this concept, showing that in healthy lungs, deflation mechanisms are based on the sequential de-recruitment of airspaces. Using PCSRCT scans in an animal model of acute respiratory distress syndrome (ARDS), this study examined whether the numerosity (ASnum) and dimension (ASdim) of lung airspaces change during a deflation maneuver at decreasing levels of positive end-expiratory pressure (PEEP) at 12, 9, 6, 3, and 0 cmH2O. Deflation was associated with significant reduction of ASdim both in the whole lung section (passing from from 13.1 ± 2.0 at PEEP 12 to 7.6 ± 4.2 voxels at PEEP 0) and in single concentric regions of interest (ROIs). However, the regression between applied PEEP and ASnum was significant in the whole slice (ranging from 188 ± 52 at PEEP 12 to 146.4 ± 96.7 at PEEP 0) but not in the single ROIs. This mechanism of deflation in which reduction of ASdim is predominant, differs from the one observed in healthy conditions, suggesting that the peculiar alveolar micromechanics of ARDS might play a role in the deflation process.

Experimental study of a waveguide free‐electron laser using the coherent synchrotron radiation emitted from electron bunches

1994 ◽  
Vol 64 (13) ◽  
pp. 1601-1603 ◽  
Author(s):  
Makoto Asakawa ◽  
Naoki Sakamoto ◽  
Naoki Inoue ◽  
Tatsuya Yamamoto ◽  
Kunioki Mima ◽  
...  
Keyword(s):  
Experimental Study ◽  
Synchrotron Radiation ◽  
Free Electron ◽  
Free Electron Laser ◽  
Electron Bunches ◽  
Coherent Synchrotron Radiation

Generation of picosecond electron bunches in storage rings

2014 ◽  
Vol 21 (5) ◽  
pp. 961-967 ◽  
Author(s):  
Xiaobiao Huang ◽  
Thomas Rabedeau ◽  
James Safranek
Keyword(s):  
Storage Ring ◽  
Short Pulse ◽  
Storage Rings ◽  
High Repetition Rate ◽  
Light Sources ◽  
X Ray ◽  
Electron Bunches ◽  
Performance Challenges ◽  
Synchrotron Light Sources ◽  
Srf Cavities

Approaches to generating short X-ray pulses in synchrotron light sources are discussed. In particular, the method of using a superconducting harmonic cavity to generate simultaneously long and short bunches in storage rings and the approach of injecting short bunches from a linac injector into a storage ring for multi-turn circulation are emphasized. If multi-cell superconducting RF (SRF) cavities with frequencies of ∼1.5 GHz can be employed in storage rings, it would be possible to generate stable, high-flux, short-pulse X-ray beams with pulse lengths of 1–10 ps (FWHM) in present or future storage rings. However, substantial challenges exist in adapting today's high-gradient SRF cavities for high-current storage ring operation. Another approach to generating short X-ray pulses in a storage ring is injecting short-pulse electron bunches from a high-repetition-rate linac injector for circulation. Its performance is limited by the microbunching instability due to coherent synchrotron radiation. Tracking studies are carried out to evaluate its performance. Challenges and operational considerations for this mode are considered.

scholarly journals GRB spectral parameter modeling

2010 ◽  
Vol 6 (S274) ◽  
pp. 243-245
Author(s):  
Gregory D. Fleishman ◽  
Fedor A. Urtiev
Keyword(s):  
Synchrotron Radiation ◽  
Electric Fields ◽  
Large Scale ◽  
Gamma Ray ◽  
Small Scale ◽  
Random Waves ◽  
Spectral Parameters ◽  
Random Magnetic Field ◽  
Cross Correlations ◽  
Accelerated Particles

AbstractFireball model of the gamma-ray bursts (GRBs) predicts generation of numerous internal shocks, which efficiently accelerate charged particles and generate relatively small-scale stochastic magnetic and electric fields. The accelerated particles diffuse in space due to interaction with the random waves and so emit so called Diffusive Synchrotron Radiation (DSR) in contrast to standard synchrotron radiation they would produce in a large-scale regular magnetic fields. In this contribution we present key results of detailed modeling of the GRB spectral parameters, which demonstrate that the non-perturbative DSR emission mechanism in a strong random magnetic field is consistent with observed distributions of the Band parameters and also with cross-correlations between them.

Effect of Ring-Planet Mesh Phasing and Contact Ratio on the Parametric Instabilities of a Planetary Gear Ring

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Sripathi Vangipuram Canchi ◽  
Robert G. Parker
Keyword(s):  
Parametric Excitation ◽  
Planetary Gear ◽  
Time Varying ◽  
Ring Gear ◽  
Contact Ratio ◽  
System Parameters ◽  
Gear Ring ◽  
Parametric Instabilities ◽  
Planetary Gear System ◽  
Mesh Phasing

Parametric excitation of a rotating ring subject to moving time-varying stiffnesses has previously been investigated and given as closed-form expressions in the system parameters. These conditions are applied to identify ring gear parametric instabilities in a planetary gear system. Certain mesh phasing and contact ratio conditions suppress parametric instabilities, and these conditions are presented with examples.

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