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The Quest For the Ultimate Vacuum Tube (ieee.org)
An anonymous reader writes: IEEE Spectrum reports on progress in the development of vacuum tube technology, which remains surprisingly relevant in 2015. "In the six decades since vacuum tubes lost out to solid-state devices in computers, receivers, and power supplies, vacuum technology has continued to evolve and branch out into new terrain, sustaining a small but skilled corps of engineers and scientists around the world, as well as a multibillion-dollar industry. That's because the traveling-wave tube and other vacuum devices continue to serve one purpose extremely well: as powerful sources of microwave, millimeter-wave, and submillimeter-wave radiation. And now, ongoing research into a new and potentially revolutionary kind of traveling-wave tube—the ultracompact and ultraefficient cold-cathode TWT—looks poised to deliver the first practical device by the end of this decade."
EMPs are the death of solid state devices. But, due to their nature, vacuum tubes can weather EMPs fairly easily.
Light travels faster than sound. This is why some people appear bright until you hear them speak.........
Could learn a thing or two from studying vacuum tube technology. Unlike most everything casts from silicon, you can actually "see" electron flow, with enough certainty to end the conceptual debate between hole flow and electron flow.
Nothing evolves faster than the word of god in the minds of men who think themselves divinely inspired.
In my experience, when someone feels the need to insist that something is "surprisingly relevant", it's usually unsurprisingly irrelevant.
What a surprisingly relevant insight...
Do not look into laser with remaining eye.
The other place vacuum tube technology in a big way still exists is Photomultiplier tubes. Photodiode technology has come on significantly, but for very low light level applications PMTs win. They lose out in quantum efficiency to silicon and ingaas photodiodes at almost all wavelengths of light PMT are actually useful at. But the internal amplification of the tubes means dark noise is very low at low light levels. To the point that PMTs can detect single photon events (photon counting) with a collection area of an inch or larger. Avalanche photodiodes (photodiodes with internal amplification) can do photon counting but only on devices less than a mm, which limits their applications.
Of course PMTs have their weirdnesses. The gain you apply is not able to be known accurately. The devices have weird non-linearities at low gain. They have a polarisation bias. And many more.
About 70 years ago, E. E. "Doc" Smith wrote a series of books that are wonderful space opera: the "Lensman" series. The space battles just keep escalating throughout the series, getting more over-the-top.
My favorite plot point: they used the principles of a vacuum tube to make a device whose pieces included grids mounted in the asteroid belt, with more in other orbits closer in to the sun. In effect they turned the inner Solar System into one honking big vacuum tube, and created a weapon that could concentrate a significant fraction of the sun's output onto attacking enemy fleets. This was called the "Sunbeam". (Believe it or not, this wasn't the end of the escalation. The battles got even bigger after that.)
When you say "ultimate" vacuum tube, I think that one is pretty hard to top.
P.S. 200-word crossover fan fiction: what would have happened if the Battlestar Galactica reboot show had found Earth, and it was the Earth of the Lensman series?
http://archiveofourown.org/works/495034
When I was a teen and read those books, I just enjoyed them, but now I'm thinking that it would take a lot of trust to allow Kimball Kinnison to run around acting as judge, jury, and executioner. As readers of the books, we know that he was vetted as deeply as anyone could be by the Arisians, so he can be trusted with that kind of power; but it would be hard for the ordinary people in the world of the books to trust him that much.
lf(1): it's like ls(1) but sorts filenames by extension, tersely
I read somewhere that they still use tubes in communication satellites for that reason. Because cooling is difficult (no air to draw heat away) tubes are more efficient to send up as you don't need massive heat sinks to keep their solid state counterparts from melting.
My Other Computer Is A Data General Nova III.