scholarly journals High brightness electron beam emittance evolution measurements in an rf photoinjector

2008 ◽  
Vol 11 (3) ◽  
Author(s):  
A. Cianchi ◽  
D. Alesini ◽  
A. Bacci ◽  
M. Bellaveglia ◽  
R. Boni ◽  
...  
Keyword(s):  
Electron Beam ◽  
Beam Emittance ◽  
High Brightness ◽  
Rf Photoinjector ◽  
Emittance Evolution

scholarly journals Synchrotron Radiation Sources – Present Capabilities and Future Directions

1998 ◽  
Vol 5 (3) ◽  
pp. 168-175 ◽  
Author(s):  
Herman Winick
Keyword(s):  
Electron Beam ◽  
High Energy ◽  
Storage Rings ◽  
Light Sources ◽  
Beam Emittance ◽  
High Brightness ◽  
Performance Levels ◽  
Electron Sources ◽  
Short Period ◽  
Pass Through

Many of the more than 40 operational light sources around the world have achieved performance levels that exceed initial design goals. These accomplishments are reviewed, along with concepts and proposals for sources with performance levels exceeding those of present sources. These include storage rings with lower electron-beam emittance than present third-generation rings and free-electron lasers (FELs). It now appears that the highest performance sources will be based on linacs rather than storage rings. This is because emittance originates differently and scales differently with electron energy for rings and linacs, so that the lowest electron-beam emittance can be achieved in high-energy linacs equipped with high-brightness electron sources. Such electron beams can be used to provide X-ray beams with very high brightness and coherence in sub-picosecond pulses in a single pass through a small-gap short-period undulator by spontaneous emission, and with even higher beam brightness and coherence by stimulated coherent emission in an FEL. Designs for such FEL sources, and associated research and development, are underway at several laboratories.

Performance and applications of the holography electron microscope

1993 ◽  
Vol 51 ◽  
pp. 1078-1079
Author(s):  
Akira Tonomura
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Phase Measurement ◽  
Electron Holography ◽  
Imaging Method ◽  
High Contrast ◽  
Magnetic Lens ◽  
High Brightness ◽  
Holographic Imaging ◽  
Dynamic Observation

Electron holography is a two-step imaging method. However, the ultimate performance of holographic imaging is mainly determined by the brightness of the electron beam used in the hologram-formation process. In our 350kV holography electron microscope (see Fig. 1), the decrease in the inherently high brightness of field-emitted electrons is minimized by superposing a magnetic lens in the gun, for a resulting value of 2 × 109 A/cm2 sr. This high brightness has lead to the following distinguished features. The minimum spacing (d) of carrier fringes is d = 0.09 Å, thus allowing a reconstructed image with a resolution, at least in principle, as high as 3d=0.3 Å. The precision in phase measurement can be as high as 2π/100, since the position of fringes can be known precisely from a high-contrast hologram formed under highly collimated illumination. Dynamic observation becomes possible because the current density is high.

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.

Brazing Vacuum Ceramic Tubes - A Diffusion Profile in the Joint

2016 ◽  
Vol 367 ◽  
pp. 86-95
Author(s):  
Osmar Roberto Bagnato ◽  
R.F. Francisco ◽  
A.L. Gobbi ◽  
Tatiane Falvo ◽  
P.M. Pimentel
Keyword(s):  
Electron Beam ◽  
High Vacuum ◽  
Diffusion Profile ◽  
Film Deposition ◽  
High Brightness ◽  
Vacuum Chambers ◽  
Ceramic Components ◽  
Synchrotron Light ◽  
The Magnetic Field ◽  
Design Construction

The Sirius Project is an initiative of the Brazilian Synchrotron Light Laboratory - LNLS (CNPEM - MCTI), for the design, construction and operation of a new synchrotron radiation source 3rd generation, with high brightness and energy of the electrons of 3.0 GeV. Among many other components there will be built 80 ceramic cameras embedded in special magnets, whose function is to act to correct the orbit of the electron beam in the storage ring. The ceramic chamber is crucial for this application because this material is transparent to the magnetic field generated in the electro magnet and thus acts directly on the electron beam. The difficulty of these constructive components lies in the fact that, the ceramic components must be attached to metal components will join vacuum chambers that make up the ring, and then must present excellent mechanical and vacuum tight. The process of chemical bonding between the ceramic and metal components is performed by brazing in high vacuum. After brazing, a film is deposited of copper with 7 micrometers thickness. The objective of this paper is to describe the process of film deposition and brazing of copper and the excellent results obtained in the production, mechanical characterization, microstructural and tightness.

Sign in / Sign up

Export Citation Format

Share Document