Electron-optical system

The fine-focus electron optical system of the General Electric X-ray Microscope has been used as the basis for an x-ray emission electron-microprobe.9 10... 

The principle of producing high-energy electrons is very simple. The electrons are emitted in a vacuum by a heated cathode and accelerated in the electrostatic field applied between cathode and anode. Acceleration takes place from the cathode, which is on negative high voltage potential to the grounded accelerator vessel as anode. Usually, an electron optical system is used to focus the accelerated electrons to the accelerator window plane. 

As already discussed, there is an important case where resolution is determined by fundamental limitations of the electron optical system and not by electron scattering. This occurs with the high current shaped electron beams used in high throughput direct-write tools. The Coulomb interaction between electrons in these columns displaces the electrons from their intended trajectories and blurs the edges of the spot. As discussed above in connection to throughput, this effect, which is related to the Boersch effect (45) forces a compromise between throughput and resolution. 

As shown by Fig. 6. electrons from an electron gun are directed to die sample through an electron optical system. Once the electron beam... 

After these explanations the content of equ. (10.44b) can be formulated as follows for an ideal electron-optical system the overall intensity of transmitted electrons remains constant and separates into two factors, one (the luminosity) describing the geometrical parameters which the electrons have on either side of the system, the other (the brightness) describing the kinetic energies. 

Abstract. This work is devoted to development of the effective electron gun for the triode light sources. The electron gun is based on field emission cathode made of a bundle of PAN carbon fibers encapsulated into a glass capillary. The complex of researches on optimization of electron-optical system has been carried out. 

Keywords Field emission, carbon fibers, plasmachemical treatment, light source, electron-optical system... 

The purpose of the current work is the development of the effective electron-optical system for the cathodoluminescent light source with the field emission cathode based on polyacrylonitrile (PAN) carbon fibers [1]. 

The electron-optical system of the cathodoluminescent lamp consists of electron gun and luminescent screen, which is covered by phosphor. It represents the triode construction. The base of this triode is the cathode-modulator unit (CMU) that consists of field emission cathode and extraction electrode (modulator). 

The electron-optical system of a lamp should provide high operating ratio of field emission current emitted by the cathode. Earlier the prototype design of the... 

The effective electron-optical system with the field emission cathode based on PAN carbon fibers is developed. Modernization of electron gun design has allowed to decrease operating voltages of the light source essentially and to enhance the cathode current transmitting. 

Both systems operate on similar principles. A tungsten filament emits electrons, which are focused by an electron optical system. The electron beam can scan the sample surface and can provide composition at a point, along a line or over a rectangular area, by rastering the beam across the surface in a series of parallel lines. The sample is mounted on a stage that can be accurately moved in the x and y directions and in the z direction, normal to the plane of the sample. The system has an optical microscope, to permit alignment of the sample and selection of the area or feature of the sample to be analyzed. 

The design of a gas electron diffraction apparatus is similar to that of an electron microscope, but the electron optical system is much simpler. The sample gas is introduced into the diffraction chamber through a nozzle, and the electrons scattered by the sample molecules near the nozzle tip are either collected on a photographic plate or measured directly by electron counting. Typical experimental condi-... 

Electron beam n. A stream of electrons in an electron optical system. 

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