Editing Cold cathode (section)

==Cold-cathode devices==
[[Image:ZM1210-operating edit2.jpg|thumb|upright|
The stacked digit arrangement in a [[Nixie tube]] is visible here]]

A cold-cathode vacuum tube does not rely on external heating of an electrode to provide [[thermionic emission]] of electrons. Early cold-cathode devices included the [[Geissler tube]] and [[Julius Plücker|Plucker tube]], and early [[cathode-ray tube]]s.  Study of the phenomena in these devices led to the discovery of the electron.

[[Neon lamp]]s are used both to produce light as indicators and for special-purpose illumination, and also as circuit elements displaying [[negative resistance]]. Addition of a trigger electrode to a device allowed the glow discharge to be initiated by an external control circuit; [[Bell Laboratories]] developed a "trigger tube" cold-cathode device in 1936.<ref>D. M. Neale, ''Cold Cathode Tube Circuit Design'', Francis and Taylor, 1964. pp. 1–7.</ref>

Many types of cold-cathode switching tube were developed, including various types of [[thyratron]], the [[krytron]], cold-cathode displays ([[Nixie tube]]) and others. [[Voltage regulator]] tubes rely on the relatively constant voltage of a [[glow discharge]] over a range of current and were used to stabilize power-supply voltages in tube-based instruments. A [[Dekatron]] is a cold-cathode tube with multiple electrodes that is used for counting.  Each time a pulse is applied to a control electrode, a glow discharge moves to a step electrode; by providing ten electrodes in each tube and cascading the tubes, a counter system can be developed and the count observed by the position of the glow discharges. Counter tubes were used widely before development of [[integrated circuit]] counter devices.

The [[flash tube]] is a cold-cathode device filled with [[xenon]] gas, used to produce an intense short pulse of light for photography or to act as a [[stroboscope]] to examine the motion of moving parts.

===Lamps===
Cold-cathode lamps include [[cold-cathode fluorescent lamp]]s (CCFLs) and [[neon lamp]]s. Neon lamps primarily rely on excitation of gas molecules to emit light; CCFLs use a discharge in mercury vapor to develop ultraviolet light, which in turn causes a [[fluorescence|fluorescent]] coating on the inside of the lamp to emit visible light.

Cold-cathode fluorescent lamps were used for [[backlight]]ing of [[LCD]]s, for example computer monitors and television screens.

In the lighting industry, “cold cathode” historically refers to luminous tubing larger than 20&nbsp;mm in diameter and operating on a current of 120 to 240 milliamperes. This larger-diameter tubing is often used for interior alcove and general lighting.<ref>{{cite web | title = Ifay guide info electric discharge lighting systems, cold cathode| url =http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name=IFAY.GuideInfo&ccnshorttitle=Electric+Discharge+Lighting+Systems,+Cold+Cathode&objid=1074096534&cfgid=1073741824&version=versionless&parent_id=1073988136&sequence=1}}</ref><ref>{{cite web|title=EGL lighting products |url=http://www.egl-lighting.com/products.html |access-date=9 February 2011 |url-status=dead |archive-url=https://web.archive.org/web/20101026042259/http://www.egl-lighting.com/products.html |archive-date=October 26, 2010 }}</ref>
The term "neon lamp" refers to tubing that is smaller than 15&nbsp;mm in diameter{{citation needed|date=September 2015}} and typically operates at approximately 40 milliamperes.  These lamps are commonly used for neon signs.