Vacuum tubes in a guitar amplifier. Shane Gorski The transistor revolutionized the world and made the abundant computing we now rely on a possibility, but before the transistor, there was the vacuum tube. Large, hot, power hungry, and prone to failure, vacuum tubes are a now-forgotten relic of the very earliest days of computing. But there’s a chance that vacuum tube technology could make its way back into computers—albeit without the vacuum—thanks to NASA research that has put together nanoscale “vacuum channel” transistors that can switch at more than 400GHz. Vacuum tubes have three important components: two electrodes—the negative, electron-emitting cathode, and the positive, electron-receiving anode—and a control grid placed between them. The flow of current between the cathode and the anode is controlled by the grid; the higher the voltage applied to the grid, the greater the amount of current that can flow between them. All three parts are housed in an evacuated glass tube or bulb and look somewhat like a kind of overcomplicated light bulb. The thing that made vacuum tubes so hot and power hungry was the cathode. Electrons can be encouraged to cross gaps by using very high voltages, but these tend to be difficult to work with. Instead, a phenomenon called thermionic emission is used—heat a piece of metal up enough, and the thermal energy lets the electrons escape the metal. Vacuum tubes have heating elements to make the cathode hot enough to emit electrons. Read 8 remaining paragraphs | Comments
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NASA melds vacuum tube tech with silicon to fill the terahertz gap
