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The Quest For the Ultimate Vacuum Tube (ieee.org)

Posted by Soulskill on from the one-tube-to-rule-them-all dept.

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."

10 of 109 comments (clear)

  1. Vacuum tubes handle EMP's better by QuietLagoon · · Score: 5, Interesting

    EMPs are the death of solid state devices. But, due to their nature, vacuum tubes can weather EMPs fairly easily.

    1. Re:Vacuum tubes handle EMP's better by rubycodez · · Score: 4, Informative

      Vaccuum tube radios were damaged by EMP in the 1962 Kazakhstan Soviet tests, as were diesel generators (shorted windings).

      Facts are our friends.

    2. Re:Vacuum tubes handle EMP's better by TWX · · Score: 4, Funny

      No, happy accident. Kind of like how the old government buildings will protect their inhabitants from the radiation due to all of the lead paint.

      --
      Do not look into laser with remaining eye.
    3. Re:Vacuum tubes handle EMP's better by gstoddart · · Score: 4, Funny

      And, they won't burn due to all of the asbestos. It really is a win-win situation. ;-)

      --
      Lost at C:>. Found at C.
    4. Re:Vacuum tubes handle EMP's better by Anonymous Coward · · Score: 5, Informative

      Yes. The voltage spike was enough to cause internal arcs in operating tubes, vaporizing electrode material..
      So the solution for tube equipment is the same as it it for BJTs and FETs - Faraday shield and heavy transient suppression on any unshielded conductors penetrating.
      Just less of it required for tubes as they can tolerate instantaneous voltages well in excess of their rated operating voltages and can dissipate a bit of energy without taking permanent damage, though for complex ultraminiature tubes those margins are orders of magnitude lower than for a simple dumb big triode.

    5. Re:Vacuum tubes handle EMP's better by Ormy · · Score: 4, Informative

      I'm getting quite fed up of this myth. Solid state electronics are _momentarily_ disrupted by strong EMP, volatile and some non-volatile memory is wiped, so yes in a mission-critical situation they're not always suitable but capacitors and resistors and transistors all work just fine after the EMP has passed (seconds at most). I witnessed an experiment a few years ago where a strong but highly-localised EMP was directed onto a running consumer PC (windows 95 era). The computer predictably shut down, the CRT monitor had resetted to factory settings but otherwise worked just fine. The PC wouldn't boot because the BIOS had beed completely erased along with HDD firmware and the like, but we transplanted the CPU into a fresh machine and it worked just fine. Anything that doesn't rely on firmware or settings or OS stored on solid state (or magnetic) memory will likely function perfectly after (if not during) an EMP. As a simple example, an EMP would wipe all your gameboy/atari 2600 cartridges but the console hardware would still be working. I'm not trying to downplay the continued-yet-widely-unknown usefulness of vacuum tubes, its just this misconception about EMPs really annoys me sometimes.

  2. Yeah, but he REAL test!!! by cayenne8 · · Score: 5, Funny
    How does it sound in a guitar amp???

    ;)

    --
    Light travels faster than sound. This is why some people appear bright until you hear them speak.........
    1. Re:Yeah, but he REAL test!!! by confused+one · · Score: 5, Funny

      Punchy lows. Solid mids. But where it really excels is highs. They're crisp and clear all the way to 200GHz and beyond. Of course you'll have to use our superflex cable with gold plated oxygen free copper conductors to really hear the difference!

  3. Re:My beanburger tastes like real meat, which I ha by TWX · · Score: 4, Funny

    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.
  4. Re:Many a young engineer.... by Too+Much+Noise · · Score: 4, Informative

    If only it were as simple as that. He's still right about one thing though, your initial statement about "conceptual debate between hole flow and electron flow" is misguided. It's just the reasoning that's ... inexact.

    Both 'electron flow' and 'hole flow' are pseudo-particle descriptions of many-body transport phenomena. Heck, there are systems where the pseudo-electrons have anisotropic mass, charge/spin separation, and so on - hardly the behaviour of a free electron. Besides, that 'a free valence band' term you used is misleading - a vacancy is as ill-defined spatially as an extra electron in a strongly-interacting many-body system. 'Electron' and 'hole' flows both are the same concept - quasiparticle linearizations of otherwise (mathematically) intractable systems. So there is no 'conceptual debate', yet neither is a 'real boy^H particle'