Mystery valve or.....?

[threeseven]

Can anyone identify this strange looking valve like object?

[high_vacuum_house]

Good afternoon,
I think it is an ionisation vacuum gauge to be fitted onto a high vacuum system and the amount of ionisation between the electrodes gives an indication of the level of vacuum. what does the writing on the envelope say?

Christopher Capener

[Jeremy M0RVB]

Yes, vacuum gauge. I've seen that type but not got one - they come in a variety of shapes, sizes and function, e.g.:
http://www.tubecollector.org/list.php?L=-g&M=Y&D=Y&H=Gu

Jeremy

[GrimJosef]

I used to use them. Very nice, until you inadvertently apply a very large magnetic field . Oh well, you live and learn.

Cheers,

GJ

[Herald1360]

Do I smell a superconducting magnet somewhere? High vacuum and large magnetic fields?

[Malcolm G6ANZ]

Sputter ion pumps use powerful magnets to enable them to absorb molecules from a vacuum system.

Malcolm

[threeseven]

The info on the envelope is Megatech MI-75p.

[GrimJosef]

This picture gives an albeit sketchy idea of what ion gauges look like in operation. The two yellow-orange patches of light surround the two gauges we were using to monitor the high vacuum in this laser system. (You can see the picture in higher resolution here http://i1180.photobucket.com/albums/...ps88a07228.jpg.)

Originally Posted by Herald1360

Do I smell a superconducting magnet somewhere? High vacuum and large magnetic fields?

No Chris, it was just a conventional one. This laser is powered by an extremely intense (500 kilovolt, 100 kiloamp) pulsed electron beam generated from a cold cathode in a 10^-6 torr vacuum - hence the ion gauges and the turbo pump. The pulse lasted just 10 nanoseconds ! At that sort of current the electron beam tends to 'pinch', concentrating it to the point where it melts expensive parts of the machine. So to keep the electrons on the straight and not-too-narrow we used a racetrack-shaped coil of copper tube connected to a very large welding supply to produce an, um, competitive magnetic field. Things were fine provided you remembered to turn the ion gauges off before you turned the magnet supply on. If you didn't then they went off anyway, never to come back on again, as the fragile filaments succumbed to the substantial Laplace force.

Cheers,

GJ

[ColinTheAmpMan1]

Originally Posted by Herald1360

Do I smell a superconducting magnet somewhere? High vacuum and large magnetic fields?

One type of scientific instrument using high vacuum and large magnetic fields would be a mass spectrometer. High vacuum so that the positive ions can get round the flight-tube without colliding into gas molecules and magnetic fields to select the different masses. I used to work with these lovely things some years ago. Lots of knobs and dials!
Colin.