scholarly journals Development of high brightness electron gun for advanced accelerators and radiation sources. CRADA final report

1995 ◽  
Author(s):  
I Ben-Zvi ◽  
K Batchelor
Keyword(s):  
Electron Gun ◽  
Final Report ◽  
High Brightness ◽  
Radiation Sources

Optical characteristics of the hitachi HF-2000 cold field-emission TEM

1993 ◽  
Vol 51 ◽  
pp. 1076-1077
Author(s):  
L. F. Allard ◽  
E. Völkl ◽  
T. A. Nolan
Keyword(s):  
Field Emission ◽  
Recent Literature ◽  
Electron Gun ◽  
High Brightness ◽  
Condenser Lens ◽  
Illumination System ◽  
High Resolution Images ◽  
Imaging Mode ◽  
Better Than ◽  
Illuminating System

The illumination system of the cold field emission (CFE) Hitachi HF-2000 TEM operates with a single condenser lens in normal imaging mode, and with a second condenser lens excited to give the ultra-fine 1 nm probe for microanalysis. The electron gun provides a guaranteed high brightness of better than 7×l08 A/cm2/sr, more than twice the guaranteed brightness of Schottky emission guns. There have been several articles in the recent literature (e.g. refs.) which claim that the geometry of this illumination system yields a total current which is so low that when the beam is spread at low magnifications (say 10 kX), the operator must “keep his eyes glued to the binoculars” in order to see the image. It is also claimed that this illuminating system produces an isoplanatic patch (the area over which image character does not vary significantly) at high magnification which is so small that the instrument is ineffective for recording high resolution images.

Point-Cathode Electron Gun Using Electron-Beam Bombardment for Cathode Tip Heating

1990 ◽  
Vol 48 (1) ◽  
pp. 198-199
Author(s):  
Ryo Iiyoshi ◽  
Susumu Maruse ◽  
Hideo Takematsu
Keyword(s):  
Electron Beam ◽  
Tungsten Wire ◽  
Local Heating ◽  
Electron Gun ◽  
Original Position ◽  
Beam Power ◽  
Radius Of Curvature ◽  
High Brightness ◽  
Beam Focusing ◽  
Time Operation

Point cathode electron gun with high brightness and long cathode life has been developed. In this gun, a straightened tungsten wire is used as the point cathode, and the tip is locally heated to higher temperatures by electron beam bombardment. The high brightness operation and some findings on the local heating are presented.Gun construction is shown in Fig.l. Small heater assembly (annular electron gun: 5 keV, 1 mA) is set inside the Wehnelt electrode. The heater provides a disk-shaped bombarding electron beam focusing onto the cathode tip. The cathode is the tungsten wire of 0.1 mm in diameter. The tip temperature is raised to the melting point (3,650 K) at the beam power of 5 W, without any serious problem of secondary electrons for the gun operation. Figure 2 shows the cathode after a long time operation at high temperatures, or high brightnesses. Evaporation occurs at the tip, and the tip part retains a conical shape. The cathode can be used for a long period of time. The tip apex keeps the radius of curvature of 0.4 μm at 3,000 K and 0.3 μm at 3,200 K. The gun provides the stable beam up to the brightness of 6.4×106 A/cm2sr (3,150 K) at the accelerating voltage of 50 kV. At 3.4×l06 A/cm2sr (3,040 K), the tip recedes at a slow rate (26 μm/h), so that the effect can be offset by adjusting the Wehnelt bias voltage. The tip temperature is decreased as the tip moves out from the original position, but it can be kept at constant by increasing the bombarding beam power. This way of operation is possible for 10 h. A stepwise movement of the cathode is enough for the subsequent operation. Higher brightness operations with the rapid receding rates of the tip may be improved by a continuous movement of the wire cathode during the operations. Figure 3 shows the relation between the beam brightness, the tip receding rate by evaporation (αis the half-angle of the tip cone), and the cathode life per unit length, as a function of the cathode temperature. The working life of the point cathode is greatly improved by the local heating.

Compact high brightness radiation sources

1996 ◽  
Author(s):  
K. Imasaki ◽  
M. Fujita ◽  
J. Chen ◽  
M. Asakawa ◽  
S. Nakai ◽  
...  
Keyword(s):  
High Brightness ◽  
Radiation Sources

High brightness picosecond electron gun

2005 ◽  
Vol 76 (8) ◽  
pp. 085108 ◽  
Author(s):  
M. Merano ◽  
S. Collin ◽  
P. Renucci ◽  
M. Gatri ◽  
S. Sonderegger ◽  
...  
Keyword(s):  
Electron Gun ◽  
High Brightness

Real Time Magnetic Imaging by Spin-Polarized Low Energy Electron Microscopy with Highly Spin-Polarized and High Brightness Electron Gun

2010 ◽  
Vol 3 (2) ◽  
pp. 026601 ◽  
Author(s):  
Masahiko Suzuki ◽  
Michihiro Hashimoto ◽  
Tsuneo Yasue ◽  
Takanori Koshikawa ◽  
Yasuhide Nakagawa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Real Time ◽  
Low Energy ◽  
Energy Electron ◽  
Electron Gun ◽  
High Brightness ◽  
Magnetic Imaging ◽  
Spin Polarized ◽  
Low Energy Electron

scholarly journals Performance of an electron gun for a high-brightness X-ray generator

2008 ◽  
Vol 15 (3) ◽  
pp. 258-261 ◽  
Author(s):  
Takashi Sugimura ◽  
Satoshi Ohsawa ◽  
Mitsuo Ikeda
Keyword(s):  
Electron Gun ◽  
High Brightness ◽  
X Ray

Interference Experiments with a Field Emission Source

1970 ◽  
Vol 28 ◽  
pp. 534-535
Author(s):  
A. V. Crewe ◽  
J. Saxon
Keyword(s):  
Field Emission ◽  
Spherical Aberration ◽  
Electron Gun ◽  
Partial Coherence ◽  
Vacuum System ◽  
High Brightness ◽  
Small Spot ◽  
Tungsten Tip ◽  
Effective Source ◽  
Better Than

Field emission from a tungsten tip provides a source with very high brightness and high partial coherence. An electron gun of low spherical aberration is used to focus the electrons from the tip to a small spot about 100 Å in diameter. Since the voltages applied to the tip and gun are stable to better than 5 ppm, the temporal coherence is limited by the energy spread of the source, about 200 mv.Using the focused spot a few centimeters below the gun as an effective source, a metalized quartz fiber about 2 μ in diameter is positioned a few centimeters below the source, as shown in Fig. 1. Two cylindrica11y symmetric magnetic lenses are used to magnify the resulting Fresnel diffraction pattern. The image is produced on a fluorescent coating deposited on the vacuum side of a fiber optic window. The image is recorded directly on film placed against the window outside the vacuum system.

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