Development of Field-Emission Gun for High-Voltage Electron Microscope

1990 ◽  
Vol 48 (2) ◽  
pp. 94-95
Author(s):  
T. Tomita ◽  
S. Katoh ◽  
H. Kitajima ◽  
Y. Kokubo ◽  
Y. Ishida
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Field Emission ◽  
High Voltage ◽  
High Vacuum ◽  
Electron Gun ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Acceleration Tube

It is well known that the combination of a field emission gun (FEG) and a conventional transmission electron microscope (CTEM) is extremely important for nanometer area analysis in analytical electron microscopy. However, the smaller illumination angle and reduced energy spread of FEG than those of a conventional electron gun (W hair pin filament or LaB6) give a slowly damping envelop function in phase contrast transfer function (PCTF). Thus the FEG ensures application not only to analytical microscopy but also to high resolution electron microscopy to improve the information limit.In a high voltage electron microscope (above 200 kV), high-speed vacuum pumps have to be provided below the acceleration tube to get an ultra high vacuum (UHV) around the field emission tip located at the top of the acceleration tube. However, this method is not always the best way to provide UHV because of the poor vacuum conductance caused by the electrodes inside the acceleration tube.

Development of Field Emission Gun for High Voltage Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 604-605
Author(s):  
H. Shimoyama ◽  
C. Morita ◽  
S. Arai ◽  
N. Yokoi ◽  
K. Miyauchi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Field Emission ◽  
High Voltage ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Transmission Electron ◽  
Scanning Transmission

For the last few years we have been developing a field emission (FE) gun system for our high voltage electron microscope (HVEM) H-1250 ST (maximum accelerating voltage of 1.25 MV) at Nagoya University, in order to attain much higher level of performance of the instrument and to exploit further extended field of application. In the first stage of the project during the period from 1986 to 1987, the FE gun system had been mounted on the top of the accelerating tube, and successfully been operated at the accelerating voltage of 1 MV for the first time pin the world. The operation was very stable and high resolution images for both scanning transmission electron microscopy (STEM) and conventional transmission electron microscopy (CTEM) modes were possible at this stage. At the same time, however, several practical problems related to incorporating the FE gun into the HVEM were made clear. Since then several important modifications on instrumentation and electronics have been made and the project is now at the second stage. In this paper a brief outline of the FE gun system developed for our HVEM is described especially from the view point of instrumentation and electronics.

The Network Parameters Of The T-System In Frog Muscle Measured With The High Voltage Electron Microscope.

1975 ◽  
Vol 33 ◽  
pp. 550-551 ◽  
Author(s):  
Brenda R. Eisenberg ◽  
Lee D. Peachey
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Voltage ◽  
Sartorius Muscle ◽  
High Voltage Electron Microscopy ◽  
Network Parameters ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
T System

Analysis of the electrical properties of the t-system requires knowledge of the geometry of the t-system network. It is now possible to determine the network parameters experimentally by use of high voltage electron microscopy. The t-system was marked with exogenous peroxidase. Conventional methods of electron microscopy were used to fix and embed the sartorius muscle from four frogs. Transverse slices 0.5-1.0 μm thick were viewed at an accelerating voltage of 1000 kV using the JEM-1000 high voltage electron microscope at Boulder, Colorado and prints at x5000 were used for analysis.The length of a t-branch (t) from node to node (Fig. 1a) was measured with a magnifier; at least 150 t-branches around 30 myofibrils were measured from each frog. The mean length of t is 0.90 ± 0.11 μm and the number of branches per myofibril is 5.4 ± 0.2 (mean ± SD, n = 4 frogs).

Study on the Microstructure and Deformation Behavior of Ultrafine-Crystalline Cu-Y Ribbons

2009 ◽  
Vol 610-613 ◽  
pp. 591-597
Author(s):  
Zhi Wei Du ◽  
Z.M. Sun ◽  
B.L. Shao ◽  
A.S. Liu
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Voltage ◽  
Melt Spinning ◽  
Secondary Phase ◽  
Dislocation Slip ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Small Grains

Cu99.8Y0.2, Cu99.2Y0.8 and Cu98Y2 alloy ribbons were prepared by single roller melt spinning. The microstructure was studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), high voltage electron microscope (HVEM) and high resolution electron microscopy (HREM). The results showed that α-Cu was the dominative phase in the rapid solidification ribbons of three alloys. A secondary phase Cu4Y was detected in the Cu98Y2 ribbon by XRD. The grain size was in a range of 50-200 nm in the Cu99.2Y0.8 and Cu98Y2 ribbons. Many nano-scale twins and some dislocations existed inside the larger grains. However, the grains in Cu99.8Y0.2 ribbon were in the size of microns and the sub-grains with small misorentations were in 100-200 nm. To understand the deformation mechanism, in situ tensile test were carried out at a High Voltage Electron Microscope (HVEM). The results showed that the deformation is predominated by the dislocation slip in larger grains. To accommodate the deformation, elastic deformation occured in the small grains in the initial stage of the deformation. Meanwhile, some small grains maybe deform by grain rotations. With strain increasing, some fractures generated and propagated along the grain boundaries or across the grains.

Aberrations of Accelerating Tube for High-Voltage Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 194-195
Author(s):  
Toshimi Ohye ◽  
Yoshiki Uchikawa ◽  
Chiaki Morita ◽  
Hiroshi Shimoyama
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Spherical Aberration ◽  
Initial Energy ◽  
Electron Gun ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Inner Diameter ◽  
Paraxial Ray

The accelerating tube (AT) which accelerates electrons up to a desired energy also functions as an electrostatic lens, In the present paper, numerical calculations were conducted on the electron optical characteristics including the spherical aberration of the AT for the high voltage electron microscope. Several electron optical problems arising from a combination of the AT with a thermionic electron gun (TEG) or a field emission gun (FEG) were studied.<Estimation of aberration for AT lens> The AT consists of 34 electrodes with the inner diameter of 3.3 cm and has the overall length of 142.3 cm (Fig.l). The voltage Va is applied between the cathode and the final electrode of the AT. The initial energy of the electron incident to the AT is eVo, where Vo is the anode voltage of the electron gun mounted on the AT. The electric field inside the AT was calculated using the surface charge method. The ray tracing was carried out on the basis of the relativistic paraxial ray equation, and the cardinal elements of the AT lens were obtained.

Ratings of New Films for the High-Voltage Electron Microscope and the Radiation Damage Incurred in Taking Typical Biological Electron Micrographs

1976 ◽  
Vol 34 ◽  
pp. 580-581
Author(s):  
Murray Vernon King ◽  
Donald F. Parsons
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Image Quality ◽  
Radiation Damage ◽  
High Voltage ◽  
Radiation Doses ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Typical Specimen

Radiation damage to biological specimens being examined in the electron microscope inevitably restricts the amount of information that can be gathered. This problem is especially severe in the high-voltage electron microscope (HVEM), where the relatively low sensitivities of existing photographic materials entail inordinately long exposures to specimens to the beam that cause enhanced radiation damage, in spite of early hopes that this instrument would alleviate the radiation-damage problem.We have reported studies of the sensitivities and resolutions of commercial and experimental photographic materials for use with 1-MeV electrons. In the present study, we have chosen certain photographic materials as representing typical films used for electron microscopy or as possessing a favorable combination of sensitivity and resolution for biological electron microscopy, and we have followed the course of impairment of image quality as a selected area of a typical specimen is subjected to ever larger radiation doses.

Image converters for the high-voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 102-103
Author(s):  
Murray Vernon King ◽  
Donald F. Parsons
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Voltage ◽  
Three Dimensional ◽  
Photographic Recording ◽  
Visible Image ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron

One of the major concerns of biological electron microscopists has been that of obtaining images of biological specimens with minimal radiation damage. The problem of designing more sensitive imaging devices and materials for the high-voltage electron microscope (HVEM) becomes pressing because: 1) the relative insensitivity of conventional photographic materials to 1-MeV electrons requires inordinately long exposures unless measures are taken to enhance the sensitivity of photographic recording; 2) the relative insensitivity of conventional viewing screens requires excessive beam intensities for scanning the specimen and focusing the image unless means are found to obtain a visible image at lower beam current densities; 3) an increasing part of the practice of high-voltage electron microscopy has involved taking multiple images from the same specimen area, as in taking stereo pairs or more extensive tilt series for three-dimensional reconstruction --- this feature is inherent in high-voltage electron microscopy, and it is occasioned by the wealth of detail offered by semithin sections, which requires three-dimensional methods for decipherment

Radiation-Induced Precipitation at Thin Foil Surfaces in Ni-Be Alloys

1982 ◽  
Vol 40 ◽  
pp. 598-599
Author(s):  
T. Mukai ◽  
T. E. Mitchell
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Electron Irradiation ◽  
High Vacuum ◽  
Thin Foil ◽  
Homogeneous Precipitation ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Radiation Induced

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.

Sign in / Sign up

Export Citation Format

Share Document