Search results
Results From The WOW.Com Content Network
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.
Currently, attempts are being made to develop carbon nanotubes (CNTs) as electron-gun field emission sources. [40] [41] The use of field emission sources in electron optical instruments has involved the development of appropriate theories of charged particle optics, [37] [42] and the development of related modeling. Various shape models have ...
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 ...
The Schottky effect or field enhanced thermionic emission is a phenomenon in condensed matter physics named after Walter H. Schottky. In electron emission devices, especially electron guns, the thermionic electron emitter will be biased negative relative to its surroundings. This creates an electric field of magnitude F at the
Albert Victor Crewe (February 18, 1927 – November 18, 2009) was a British-born American physicist and inventor of the modern scanning transmission electron microscope [1] capable of taking still and motion pictures of atoms, a technology that provided new insights into atomic interaction and enabled significant advances in and had wide-reaching implications for the biomedical, semiconductor ...
For electric field strengths higher than 10 8 V⋅m −1, so-called Fowler–Nordheim (FN) tunneling begins to contribute significant emission current. In this regime, the combined effects of field-enhanced thermionic and field emission can be modeled by the Murphy-Good equation for thermo-field (T-F) emission. [35]
FEI Company (Field Electron and Ion Company) was an American company that designed, manufactured, and supported microscope technology. Headquartered in Hillsboro, Oregon , FEI had over 2,800 employees and sales and service operations in more than 50 countries around the world.
Electron-beam evaporation uses thermionics emission to create a stream of electrons that are accelerated by a high-voltage cathode and anode arrangement. Electrostatic and magnetic fields focus and direct the electrons to strike a target. The kinetic energy is transformed into thermal energy at or near the surface of the material.