scholarly journals Time behavior of an electron beam current pulse in the axial and peripheral zones of an anode in vacuum and gas-filled diodes

2021 ◽  
Vol 2064 (1) ◽  
pp. 012031
Author(s):  
D A Sorokin ◽  
M I Lomaev ◽  
A V Dyatlov ◽  
V F Tarasenko
Keyword(s):  
Electron Beam ◽  
Current Pulse ◽  
Current Density ◽  
Beam Current ◽  
Beam Current Density ◽  
Electron Beam Current ◽  
Time Behavior ◽  
Beam Current Pulse ◽  
Axial Part ◽  
A Current

Abstract The study of the time behavior of a current pulse of an electron beam generated during a high-voltage nanosecond discharge in gas-filled and vacuum diodes has been carried out. As follows from the experimental results, in both cases, the distribution of the beam current density in the plane of a grounded anode is non-uniform. The highest beam current density is recorded in the axial part of the anode. It was established that in the case of a gas-filled diode, ~ 2 ns after the onset of the beam current pulse, its shape in the axial anode zone changes relative to that in the peripheral one. It is assumed that the most probable reason for this is the effect of compensation of the charge of the beam electrons by the positive charge of ions arising in the ionization process in the paraxial zone.

scholarly journals Energy density distribution of a modulated electron beam in a source with a plasma cathode based on a low pressure arc

2021 ◽  
Vol 2064 (1) ◽  
pp. 012066
Author(s):  
V I Shin ◽  
P V Moskvin ◽  
M S Vorobyov ◽  
V N Devyatkov ◽  
N N Koval
Keyword(s):  
Electron Beam ◽  
Energy Density ◽  
Density Distribution ◽  
Current Pulse ◽  
Current Density ◽  
Beam Current ◽  
Beam Current Pulse ◽  
Energy Density Distribution ◽  
Electron Beam Generation ◽  
Arc Current

Abstract The article presents the results of studies devoted to the study of the energy density distribution in the amplitude-modulated regime of electron beam generation. It is shown that in the first ≈ 50 μs of the duration of the beam current pulse, its spatial rearrangement occurs, due to the development of the arc discharge current. Thus, the rearrangement of the arc current, which develops from the axis of the system, leads to an axial diving of the emission current density and the beam current density on the target. With the development of the arc current, the energy density on the target on the axis of the system decreases and after ≈ 50 μs takes on a steady-state value, which can change only as a result of a change in the conditions for generating an electron beam or the transition to a modulated regime of electron beam generation. It has been experimentally shown using calorimetric measurements that the shape of the electron beam current pulse with its amplitude modulation with a pulse duration of more than 100 μs has little effect on the distribution of the beam energy density in the target region.

The output window of a large-area accelerator with an increased electron-beam current density

2017 ◽  
Vol 60 (4) ◽  
pp. 570-574
Author(s):  
G. A. Baranov ◽  
V. A. Gurashvili ◽  
I. D. Djigailo ◽  
N. I. Kazachenko ◽  
S. L. Kosogorov ◽  
...  
Keyword(s):  
Electron Beam ◽  
Current Density ◽  
Beam Current ◽  
Beam Current Density ◽  
Electron Beam Current ◽  
Large Area ◽  
Output Window

Characterization of a Fixed Beam Electron Microscope with a Field Emission Gun

1976 ◽  
Vol 34 ◽  
pp. 526-527
Author(s):  
Wah Chiu ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Current Density ◽  
Beam Current ◽  
Beam Current Density ◽  
Objective Lens ◽  
Electron Beam Current ◽  
Beam Electron ◽  
Fixed Beam

One of the objectives of our research program is to obtain a 2.0 Å point to point resolution in a fixed beam bright field electron microscope. The resolution in the fixed beam electron microscope is limited by a number of factors: electron beam coherence, energy spread, objective lens stability, mechanical stability, and specimen stability. This paper presents systematic studies of the mentioned factors in our JEM 100B fixed beam electron microscope equipped with a field emission gun operating at ∼ 1800°K.The most important characteristic of a field emission gun is its high brightness in the emitter source. In order to estimate the brightness at the specimen plane, one needs to measure the electron beam current density and the angle of illumination. The electron beam current density has been measured by means of a lithium-drifted silicon detector located below the normal position of the photographic plates. The angle of illumination can be estimated from the size of the condenser aperture and its distance from the specimen plane.

An Analytical Method of Time Character of Electron Beam Current Density on Transmission Electron Microscope Imaging

2013 ◽  
Vol 694-697 ◽  
pp. 1372-1376
Author(s):  
Xiu Yan Zhang ◽  
Quan Lin Dong
Keyword(s):  
Electron Beam ◽  
Exposure Time ◽  
Current Density ◽  
Analytical Method ◽  
Least Squares Method ◽  
Beam Current ◽  
Test Equipment ◽  
Beam Current Density ◽  
Electron Beam Current ◽  
Transmission Electron

An analytical method of time character of electron beam current density is required for transmission electron microscopy (TEM) imaging research. By studying the imaging principle of TEM, the relational expression between current density on fluorescent screen and exposure time is deduced. The actual data of numerical relation between current density and exposure time are gained by the exposure experimentation with the master sample on the TEM test equipment. Furthermore, the parameter value in expression is computed by linear fit using the least squares method, and then the concrete relational expression between current density and exposure time about the TEM test equipment is obtained. As a result, using the concrete relational expression on the TEM test equipment, the automatic exposure experimentation on some samples is completed on the different operating mode, and the relatively clear-cut TEM images are formed. The experimentation results indicate that the automatic exposure method is correct and parameter calibration is valid.

scholarly journals NUMERICAL ANALYSIS OF LASING DYNAMICS IN VOLUME FREE ELECTRON LASER

2008 ◽  
Vol 13 (2) ◽  
pp. 263-273
Author(s):  
Svetlana Sytova
Keyword(s):  
Electron Beam ◽  
Free Electron ◽  
Free Electron Laser ◽  
Initial Conditions ◽  
Beam Current ◽  
Beam Current Density ◽  
Electron Beam Current ◽  
Nonlinear Phenomena ◽  
Experimental Development ◽  
Lasing Dynamics

Nonlinear phenomena originating in volume free electron laser (VFEL) are investigated by methods of mathematical modelling using computer code VOLC. It was demonstrated the possibility of excitation of quasiperiodic oscillations not far from threshold values of electron beam current density and VFEL resonator length. It was investigated sensibility of numerical solution to initial conditions for different VFEL regimes of operation. Parametric maps with respect to electron beam current and detuning from synchronism condition present complicated root to chaos with windows of periodicity in VFEL. Investigation of chaotic lasing dynamics in VFEL is important in the light of experimental development of VFEL in Research Institute for Nuclear Problems.

Methods to quantify silver in autoradiographs

1980 ◽  
Vol 238 (3) ◽  
pp. H414-H422
Author(s):  
D. L. Fry ◽  
A. J. Tousimis ◽  
T. L. Talbot ◽  
S. J. Lewis
Keyword(s):  
Electron Beam ◽  
Current Density ◽  
Electron Probe ◽  
Beam Current ◽  
Silver Concentration ◽  
Electron Beam Current ◽  
Beam Size ◽  
X Ray ◽  
Small Variance ◽  
Arterial Tissue

The developed silver in specially prepared photographic films (PF) and autoradiographs (AR) of radiolabeled arterial tissue was quantified by direct grain counting (GC), microdensitometry (OD), and by electron probe X-ray microanalysis (EPA). The EPA data was proportional to the OD data with a very small variance. The GC data increased with the EPA data, but showed a large variance. The EPA signal was shown 1) to be reproducible even after multiple traverses across the specimen, 2) to be directly proportional to the electron beam current and emulsion silver concentration, and 3) to be insensitive to a) beam size, b) current density, c) energy above 17 keV, or d) nonuniformities in the thickness of the conductive coating on the specimen.

Effects of Pulsed Electron Beam Irradiation on Al Single Crystal With Pb Overlayers

1983 ◽  
Vol 23 ◽  
Author(s):  
G. Battaglin ◽  
A. Carnera ◽  
L.F. Dona ◽  
Dalle Rose ◽  
V.N. Kulkarni ◽  
...  
Keyword(s):  
Electron Beam ◽  
Current Density ◽  
Electron Beam Irradiation ◽  
Incident Beam ◽  
Beam Current ◽  
Beam Current Density ◽  
Beam Irradiation ◽  
Monte Carlo Data ◽  
Model Calculations ◽  
Pulsed Electron Beam

ABSTRACTThe effects of pulsed electron beam irradiation (pulse width 50 ns FWHM, electron eneries from 15 to 30 keV and current density in the range of 100 to 2300 A/cm2 ) on Al-Pb systemsprepared by vacuum evaporation of Pb layers from 500 Å to 2000 Å in thickness over Al single crystals have been investigated by Rutherford backscattering (RBS) and scanning electron microscopy.The main effects consist in a Pb loss which shows definite features as a function of the incident beam current density and in a mixing of Pb into Al which is unambiguously detected by a selective chemical etching of Pb still unreacted after irradiation.These experimental results are discussed on the basis of some heat flow model calculations which use Monte-Carlo data for the electron depth dose function.

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