The Krytron is a cold-cathode gas filled tube intended for use as a very high-speed switch and was one of the earliest developments of the EG&G Corporation.


Unlike most other gas switch tubes, the krytron uses arc discharge to handle very high voltages and currents (several kV and several kA peak), rather than the usual low-current glow discharge. The krytron is a development of the triggered spark gaps and thyratrons originally developed for radar transmitters during World War II.


There are four electrodes in a krytron. Two are conventional anode and cathode. One is a keep-alive electrode, arranged to be close to the cathode. The keep-alive has a low positive voltage applied, which causes a small area of gas to ionize near the cathode. High voltage is applied to the anode, but primary conduction does not occur until a positive pulse is applied to the trigger electrode ("Grid" in the image above). Once started, arc conduction carries a considerable current. In place of or in addition to the keep-alive electrode some krytrons may contain a very tiny amount of radioactive material (usually nickel-63) which emits beta particles (high-speed electrons) to make ionization easier. The amount of radiation in a krytron is very small and not harmful.


This design, dating from the late 1940s, is still capable of pulse-power performance which even the most advanced semiconductors (even IGBT transistors) cannot match easily. The vacuum-filled version is called a Sprytron and is designed for use in environments where high levels of ionizing radiation are present (because the radiation might cause the gas-filled krytron to trigger inadvertently.)


Krytrons and their variations are still manufactured by Perkin-Elmer Components, and used in a variety of industrial and military devices. They are best known for their use in igniting the exploding-bridgewire detonators and slapper detonators in nuclear weapons, their original application, either directly or by triggering the higher-power spark gap switches. They are also used to trigger large flashlamps in photocopiers, lasers and scientific apparatus, as well as firing ignitors for industrial explosives.

Export restrictions

Because of the potential for use as nuclear triggers, the export of krytrons is tightly regulated. A number of cases involving the smuggling or attempted smuggling of krytrons have been reported, as countries seeking to develop nuclear weapons have attempted to procure supplies of krytrons for igniting their weapons.

Krytron in popular culture

A Krytron was the "MacGuffin" in Roman Polanski's 1988 film "Frantic".


* EG&G Electronic Components Catalog, 1994.

External links

* [ Krytron information on "Tube Collector" site]
* [ John Pasley's article about gas-filled switch tubes, Krytron section]
* [ Photo of a small glass krytron]
* [ 40 month sentence to illegal exporter] (though the sentence was definitely related to the 'fugitive' details)

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Krytron — KN 22, Hersteller EG G Das Krytron ist eine gasgefüllte Elektronenröhre, welche Mitte des 20. Jahrhunderts als Schaltröhre Anwendung gefunden hat. Durch die spezielle Konstruktion können sehr kurze Schaltzeiten und hohe Ströme geschaltet werden.… …   Deutsch Wikipedia

  • krytron — /krīˈtron/ (technology) noun A sophisticated electronic timing device used for detonating nuclear and other explosive charges, and for varied industrial and scientific purposes …   Useful english dictionary

  • krytron —  n.m. Tube à gaz utilisé pour la mise à feu d un détonateur nucléaire …   Le dictionnaire des mots absents des autres dictionnaires

  • Frantic — Filmdaten Deutscher Titel Frantic Produktionsland USA/Frankreich …   Deutsch Wikipedia

  • Frantic (película) — Para la primera canción del octavo álbum de Metallica, véase Frantic. Frantic Título Búsqueda frenética (México) Frenético (España) Ficha técnica Dirección Roman Polanski …   Wikipedia Español

  • Cold cathode — This article is about light sources and indicators. For cold cathode ion sources, see Ion source. CCFL redirects here. For other uses, see CCFL (disambiguation). Cold cathode fluorescent lamp A cold cathode is a cathode used within nixie tubes,… …   Wikipedia

  • Klystron — A klystron is a specialized linear beam vacuum tube (evacuated electron tube). Klystrons are used as amplifiers at microwave and radio frequencies to produce both low power reference signals for superheterodyne radar receivers and to produce high …   Wikipedia

  • Thyratron — A thyratron is a type of gas filled tube used as a high energy electrical switch and controlled rectifier. Triode, Tetrode and Pentode variations of the thyratron have been manufactured in the past, though most are of the triode design. Gases… …   Wikipedia

  • Gas-filled tube — See also: Gas discharge lamp A gas filled tube, also known as a discharge tube, is an arrangement of electrodes in a gas within an insulating, temperature resistant envelope. Although the envelope is typically glass, power tubes often use… …   Wikipedia

  • Frantic (film) — Infobox Film | name = Frantic caption = Frantic movie poster director = Roman Polanski producer = Tim Hampton Thom Mount writer = Roman Polanski Gérard Brach starring = Harrison Ford Betty Buckley John Mahoney Alexandra Stewart introducing… …   Wikipedia

Share the article and excerpts

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

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.