Search results
Results From The WOW.Com Content Network
The obsolete thermionic diode is a vacuum tube with two electrodes, a heated cathode and a plate, in which electrons can flow in only one direction, from the cathode to the plate. Among many uses, diodes are found in rectifiers to convert alternating current (AC) power to direct current (DC), demodulation in radio receivers , and can even be ...
All practical thermionic converters to date employ caesium vapor between the electrodes, which determines both the surface and plasma properties. Caesium is employed because it is the most easily ionized of all stable elements. A thermionic generator is like a cyclic heat engine and its maximum efficiency is limited by Carnot's law.
The first prototype Fleming valves, built October 1904. Early commercial Fleming valves used in radio receivers, 1919 Fleming valve schematic from US Patent 803,684.. The Fleming valve, also called the Fleming oscillation valve, was a thermionic valve or vacuum tube invented in 1904 by English physicist John Ambrose Fleming as a detector for early radio receivers used in electromagnetic ...
A thermal diode in this sense is a device whose thermal resistance is different for heat flow in one direction than for heat flow in the other direction. I.e., when the thermal diode's first terminal is hotter than the second, heat will flow easily from the first to the second, but when the second terminal is hotter than the first, little heat will flow from the second to the first.
He invented the thermionic diode 1873 (for which alternate credit was sometimes later given to Edison's assistant W. J. Hammer) [10] and coined the term eutectic in 1884. Guthrie wrote Elements of Heat in 1868 and Magnetism and Electricity in 1873 (published in 1876). [11] Guthrie was also a linguist, playwright, and poet.
Thermionic emission is the liberation of charged particles from a hot electrode whose thermal energy gives some particles enough kinetic energy to escape the material's surface. The particles, sometimes called thermions in early literature, are now known to be ions or electrons .
This is a list of vacuum tubes or thermionic valves, and low-pressure gas-filled tubes, or discharge tubes.Before the advent of semiconductor devices, thousands of tube types were used in consumer electronics.
Before thermionic valves were invented, Philipp Lenard used the principle of grid control while conducting photoelectric experiments in 1902. [4] The first vacuum tube used in radio [5] [6] was the thermionic diode or Fleming valve, invented by John Ambrose Fleming in 1904 as a detector for radio receivers. It was an evacuated glass bulb ...