wangrong
Posts : 189 Registration date : 2010-10-10
| Subject: Electric power and electronics Mon Nov 29, 2010 1:02 am | |
| Caesium vapor thermionic generators are low-power devices that convert heat energy to electrical energy. In the two-electrode vacuum tube converter, it neutralizes the space charge that builds up near the cathode, and in doing so, it enhances the current flow.[65] Caesium is also important for its photoemissive properties by which light energy is converted to electron flow. It is used in photoelectric cells because caesium-based cathodes such as the intermetallic compound K2CsSb have low threshold voltage for emission of electrons.[66] The range of photoemissive devices using caesium include optical character recognition devices, photomultiplier tubes, and video camera tubes.[67][68] Nevertheless, germanium, rubidium, selenium, silicon, tellurium, and several other elements can substitute caesium in photosensitive materials.[6] Caesium iodide (CsI) and bromide (CsBr) crystals are employed in scintillation counters widely used in mineral exploration and particle physics research as they are well suited for the detection of gamma and x-ray radiation. Caesium vapor is used in many common magnetometers.[69] The element is also used as an internal standard in spectrophotometry.[70] Like other alkali metals, caesium has a great affinity for oxygen and is used as a "getter" in vacuum tubes.[71] Other uses of the metal include high-energy lasers, vapor glow lamps, and vapor rectifiers.[6] Finish Stone Sidingfibroid uterine | |
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