X-rays with a 6VS-1 (6ВС-1)

In 2010, me having already exploited the DY86, a Czech experimenter nicknamed “DANYK” came up with an oddball Soviet vacuum stabilisator tetrode “6VS-1”, which produced copious amounts of X-rays in hot-cathode mode. He got pretty good radiographs, nevertheless. So, I have got an inspiration and obtained a few:

6VS-1 (6BC-1) tubes2.50€/piece from a Bulgarian stockpile

A specialty in these tubes is their construction. During normal mode of operation (high voltage stabilisation at a few hundred microamps max), a visible electron beam with a small diameter is focused on the thin anode plate. When overdriven at 30-40 kilovolts for a short period of time, X-rays with a sufficiently enough energy to pass through the glass are created.

6VS-1 at 35 kilovolts, observe the electron beam and Geiger counter sound.

I have built numerous high voltage supplies for these tubes back in the day. Here’s one of the prototypes, a multiplier-based 40 kilovolt supply with cathode current and frequency regulation:

6VS-1 high voltage supply prototypeThe suction cup had a high voltage resistor, in order
not to fry the 4-stage multiplier with inrush current.

And it sure did a mayhem when it ran – of course, controlled remotely:

In a head-to-head comparision with the DY86 ran in cold cathode, this is a more powerful X-ray emitter. Here’s a 4 second exposure near the tube where you can see energized particles (photons) hitting the CCD sensor, resulting in colorful “dots” in the picture:

6VS-1 4 sec exposureMaximize to see the artifacts

And now an attempt to radiography. As mentioned in the DY86 article I did not want to mess with a photosensitive paper and developing it afterwards in a dark room, so I have attempted the “fluoroscopy” method again. I used some fluorescent foil strips, from an “emergency-exit” glow in the dark sign, and some blue-emitting, calcium tungstate (scheelite) “PERLUX” intensifier screens, from the former GDR…

6VS-1 radiography attempt 1Enough for the screen to make a blu-ish shine..

6VS-1 radiography attempt 2… but not enough radiation to radiograph this way.
“DANYK” had been more lucky in this case.

This was the best output I have got with a setup described above. Maybe if I had been shining through a photosensitive paper for 30 seconds or so, the result would have been vastly improved – but that did not occur, as I have moved to real x-ray tubes shortly after this. 🙂

2 Responses for X-rays with a 6VS-1 (6ВС-1)

  1. Eamon Smyth says:

    I have acquired a 6VS-1 tube and I am seeking advice on how to run this device to emit soft x-rays on a continuous bases for R&D project. I look forward to hearing from you.

    • Jozef says:

      The electron beam will eventually “drill” a hole in the anode if ran continuously.
      To try this setup out, limit the maximum voltage on g2 to approx. 300V IIRC, e.g. with a stack of glow lamps, g1 is connected to ground and set cathode current e.g. with a potentiometer between cathode and ground. Use a microammeter to measure it.

      The tube will withstand up to 0.4mA at 35-40kV for a few seconds. For continuous run you ought to stay below 100uA though.

      Needless to say, a proper x-ray tube would do better. Please remember that this was just an experiment.

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