Wehnelt cylinder

Wehnelt cylinder

A Wehnelt cylinder is an electrode in the electron gun assembly of some thermionic devices, used for focusing and control of the electron beam. It is named after Arthur Rudolph Berthold Wehnelt, a German physicist, who invented it during the years 1902 and 1903. A Wehnelt cylinder is also known as a grid cap, and plays the role of a control grid. It is held biased to slight negative voltage relative to the cathode (usually a hot cathode). It has a shape of a hollow barrel with no top side (oriented towards the cathode) and a hole in the center of its bottom side (through which the focused electron beam escapes towards the anode).

Wehnelt cylinders are found in the electron guns of cathode ray tubes and electron microscopes, and in other applications where a thin, well-focused electron beam is required.


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Transmission electron microscopy — A TEM image of the polio virus. The polio virus is 30 nm in size.[1] Transmission electron microscopy (TEM) is a microscopy technique whereby a beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it… …   Wikipedia

  • Electron gun — An electron gun (also called electron emitter) is an electrical component that produces an electron beam that has a precise kinetic energy and is most often used in televisions and monitors which use cathode ray tube technology, as well as in… …   Wikipedia

  • Tube à rayons X — Deux tubes radiogènes Les tubes à rayons X sont des dispositifs permettant de produire des rayons X, en général pour trois types d applications : radiographie et tomographie (imagerie médicale, science des matériaux) ;… …   Wikipédia en Français

  • Кинескоп — О телепрограмме см. Кинескоп (телепередача). П …   Википедия

  • Lanthanum hexaboride — Chembox new ImageFile = ImageSize = IUPACName = OtherNames = lanthanum boride Section1 = Chembox Identifiers CASNo = 12008 21 8 PubChem = SMILES = Section2 = Chembox Properties Formula = LaB6 MolarMass = 203.776 g/mol Appearance = intense purple… …   Wikipedia

  • Strong focusing — In accelerator physics strong focusing or alternating gradient focusing is the principle that the net effect on a particle beam of charged particles passing through alternating field gradients is to make the beam converge. By contrast Weak… …   Wikipedia

  • microscope — /muy kreuh skohp /, n. 1. an optical instrument having a magnifying lens or a combination of lenses for inspecting objects too small to be seen or too small to be seen distinctly and in detail by the unaided eye. 2. (cap.) Astron. the… …   Universalium

  • фокусирующий электрод — — [Я.Н.Лугинский, М.С.Фези Жилинская, Ю.С.Кабиров. Англо русский словарь по электротехнике и электроэнергетике, Москва, 1999 г.] Тематики электротехника, основные понятия EN Wehnelt cylinderfocusing electrode …   Справочник технического переводчика

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”