Tungar tube
The Tungar tube is a special type of electron tube that was used as a rectifier for low voltages. The tubes were filled with argon gas; The cathode consisted of tungsten ( English Tungsten ) and the anode of graphite . The name of this type of tube results from the initial syllables of the words Tungsten (Wolfram) and Argon .
Since these tubes, in contrast to mercury vapor rectifiers, are able to supply several amperes of current even at low voltages of, for example, 12 volts , they were used, for example, for charging accumulators .
Today "Tungar" tubes are meaningless; their tasks were taken over by semiconductors .