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.

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.

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

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.

Electron holography of p-n junctions

1996 ◽  
Vol 54 ◽  
pp. 974-975
Author(s):  
B.G. Frost ◽  
D.C. Joy ◽  
L.F. Allard ◽  
E. Voelkl
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Ccd Camera ◽  
Image Plane ◽  
Reference Wave ◽  
Field Of View ◽  
Control Mode ◽  
Objective Lens ◽  
Electron Holography

A wide holographic field of view (up to 15 μm in the Hitachi-HF2000) is achieved in a TEM by switching off the objective lens and imaging the sample by the first intermediate lens. Fig.1 shows the corresponding ray diagram for low magnification image plane off-axis holography. A coherent electron beam modulated by the sample in its amplitude and its phase is superimposed on a plane reference wave by a negatively biased Möllenstedt-type biprism.Our holograms are acquired utilizing a Hitachi HF-2000 field emission electron microscope at 200 kV. Essential for holography are a field emission gun and an electron biprism. At low magnification, the excitation of each lens must be appropriately adjusted by the free lens control mode of the microscope. The holograms are acquired by a 1024 by 1024 slow-scan CCD-camera and processed by the “Holoworks” software. The hologram fringes indicate positively and negatively charged areas in a sample by the direction of the fringe bending (Fig.2).

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.

scholarly journals Design of an Einzel Lens with Square Cross-Section

Electronics ◽  
2021 ◽  
Vol 10 (19) ◽  
pp. 2338
Author(s):  
Michał Krysztof
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Cross Section ◽  
Vacuum Chamber ◽  
High Vacuum ◽  
Beam Current ◽  
Electron Beam Current ◽  
Beam Spot ◽  
High Vacuum Chamber ◽  
Beam Spot Diameter

In this paper, the results of modeling and simulation of a microcolumn are presented. The microcolumn is part of a developed miniature MEMS electron microscope equipped with a miniature MEMS high-vacuum micropump. Such an arrangement makes this device the first stand-alone miniature electron-optical device to operate without an external high-vacuum chamber. Before such a device can be fabricated, research on particular elements must be carried out to determine the working principles of the device. The results of the calculations described in this article help us to understand the work of a microcolumn with square holes in the electrodes. The formation of an electron beam spot at the anode is discussed. Further calculations and results show the dependence of the Einzel lens size on the electron beam spot diameter, electron beam current, and microcolumn focusing voltage. The results are used to define the optimal design of the developed MEMS electron microscope.

Low Cost 210K Gain Transmission Electron Microscope Image (TEMI) Intensifier

1981 ◽  
Vol 39 ◽  
pp. 382-383
Author(s):  
R.G. Rosemeier ◽  
M.E. Taylor ◽  
A.G. Wylie
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Low Cost ◽  
Beam Current ◽  
High Gain ◽  
Electron Beam Current ◽  
Transmission Electron ◽  
Fiber Materials ◽  
Beam Currents

There are a number of factors that limit transmission electron microscope (TEM) characterization. For example, when it is necessary to statistically assess large numbers of samples quickly, conventional time consuming film recording is not a plausible solution. In the case of many electron beam sensitive biological, polymeric, and fiber materials, great care must be taken to avoid both specimen damage or structure change by using minimum electron beam current densities. On the other hand, for mineral specimens, which are in general difficult to thin, maximum electron beam currents may not be high enough to produce anything but faint TEM images. As a result, a low cost portable TEM image (TEMI) intensifier was developed that allows both direct viewing of faint electron diffraction phenomenon as well as conventional TEM viewing. Figure 1 shows the portable high gain TEMI intensifier.

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