Cathode light tube12/5/2023 The power supply current range is 0 to 25mA and a 600V ignition followed with 300V sustained power. This is often aided by use of a lock-in circuit. Photomultiplier tubes (photomultipliers or PMTs for short) are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum.They are members of the class of vacuum tubes, more specifically vacuum phototubes. By looking for a resonance on a data plot of the voltage signal versus source tuning parameter, the light source can be tuned to the desired frequency. To tune the light source to a specific transition frequency, a tuning parameter (often the driving current) of the light source is varied. The newly created ions cause an increase in the current across the cathode/anode and a resulting change in the voltage, which can then be measured. Indirect photoionization can then occur when electron collisions with the excited atom eject an atomic electron. By shining the light source into the HCL, one can excite or even eject electrons (directly photoionize) from the atoms inside the lamp, so long as the light source includes frequencies corresponding to the right atomic transitions. Īn HCL can also be used to tune light sources to a specific atomic transition by making use of the optogalvanic effect, which is a result of direct or indirect photoionization. These photons will then excite the atoms in the sample, which will release their own photons and be used to generate data. As these excited atoms decay to lower states, they will emit photons. Both the buffer gas and the sputtered cathode atoms will in turn be excited by collisions with other atoms/particles in the plasma. The buffer gas ions will then be accelerated into the cathode, sputtering off atoms from the cathode. A large voltage across the anode and cathode will cause the buffer gas to ionize, creating a plasma. The Maltese cross has no external electrical connection. Description A diagram showing a Crookes tube connected to a high voltage supply. Īn HCL usually consists of a glass tube containing a cathode, an anode, and a buffer gas (usually a noble gas). Cathode-ray tubes (CRTs) use a focused beam of electrons deflected by electric or magnetic fields to render an image on a screen. An HCL takes advantage of the hollow cathode effect, which causes conduction at a lower voltage and with more current than a cold cathode lamp that does not have a hollow cathode. for atomic absorption spectrometers) and as a frequency tuner for light sources such as lasers. JSTOR ( December 2015) ( Learn how and when to remove this template message)īasic diagram of a hollow-cathode lamp Hollow-cathode lamps from an atomic absorption spectrometerĪ hollow-cathode lamp (HCL) is type of cold cathode lamp used in physics and chemistry as a spectral line source (e.g.Unsourced material may be challenged and removed.įind sources: "Hollow-cathode lamp" – news Please help improve this article by adding citations to reliable sources. They are not known for high light output, so they are best used as secondary lighting or in areas where not much light is needed.This article needs additional citations for verification. These companies purchase their CCFL lamps directly from us for use in their own POS repair facilities. CCFL warehouse is the leading supplier and vendor direct to the largest department stores, grocery stores, and restaurant chains in the country. CCFL lamps can be used in applications where a lamp will be dimmed or flashed, unlike most of their hot cathode counterparts. Call us today, we are here to help (402) 330-2222. They are also available in screw in spiral form just like “typical” hot cathode compact fluorescent lamps. ![]() Cold cathode tubes are also used to backlight signs and LCD displays, they’re probably what is allowing you to be able to read the text on your screen right now, in fact. For many people, the most easily identifiable example of a cold cathode lamp is the neon sign. Where are they used?Ĭold cathode lamps are used in a number of specialty applications. What sets the cold cathode lamp apart is that by using higher voltage, a cold cathode lamp does not require the cathode to be heated in order to fire and produce light. Cold Cathodes, or Cold Cathode Fluorescent Lights (CCFLs) are very similar to a normal fluorescent tube used in lighting many offices and signs. How do they work?Ī cold cathode lamp functions by using electricity emitted from cathodes to excite mercury vapors using the process of inelastic scattering in order to create fluorescence, just as a typical linear fluorescent does. They are known for high efficiency, long rated life, and their ability to start in cold conditions. CCFLs are used in a number of different specialty applications, such as cold-weather lighting, display back lighting, and signage. A cold cathode fluorescent lamp (CCFL) is a type gas-discharge lamp similar to linear fluorescent or compact fluorescent lamps.
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