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Electron gun from an oscilloscope CRT Setup of an electron gun. 1. Hot cathode.2. Wehnelt cylinder.3. Anode. A direct current, electrostatic thermionic electron gun is formed from several parts: a hot cathode, which is heated to create a stream of electrons via thermionic emission; electrodes generating an electric field to focus the electron beam (such as a Wehnelt cylinder); and one or more ...
A cross-section view, showing how a Wehnelt localizes emissions at the filament tip and serves as a convergent electrostatic lens. A Wehnelt cylinder (also known as Wehnelt cap, grid cap or simply Wehnelt) is an electrode in the electron gun assembly of some thermionic devices, used for focusing and control of the electron beam.
The betatron was the first machine capable of producing electron beams at energies higher than could be achieved with a simple electron gun, and the first circular accelerator in which particles orbited at a constant radius. [1] The concept of the betatron had been proposed as early as 1922 by Joseph Slepian. [2]
The basic components of a typical electron-beam processing device include: [1] an electron gun (consisting of a cathode, grid, and anode), used to generate and accelerate the primary beam; and, a magnetic optical (focusing and deflection) system, used for controlling the way in which the electron beam impinges on the material being processed ...
Download QR code; In other projects Appearance. move to sidebar hide ... English: Setup of an Electron Gun with Wehnelt Cylinder. Hot Cathode Wehnelt Cylinder.
The electron gun contains a heater, which heats a cathode, which generates electrons that, using grids, are focused and ultimately accelerated into the screen of the CRT. The acceleration occurs in conjunction with the inner aluminum or aquadag coating of the CRT. The electron gun is positioned so that it aims at the center of the screen. [190]
Schottky-emitter electron source of an Electron microscope. A field emission gun (FEG) is a type of electron gun in which a sharply pointed Müller-type [clarification needed] emitter [1]: 87–128 is held at several kilovolts negative potential relative to a nearby electrode, so that there is sufficient potential gradient at the emitter surface to cause field electron emission.
Multiple types of evaporation materials and electron guns can be used simultaneously in a single EBPVD system, each having a power from tens to hundreds of kilowatts. Electron beams can be generated by thermionic emission, field electron emission or the anodic arc method. The generated electron beam is accelerated to a high kinetic energy and ...