Tubes (Valves) in Outer Space

[jabney]

If one of the requirements of great tubes is getting a hard vacuum, would manufacturing tubes in outer space make that part of the task easier?

Would the extreme cold make it impossible to get a good seal around the pins? If it would work, would the getter still have to be flashed after the tube was sealed? (I would think so.)

The economics would only work for things like the 300b and re-creations of 1st generation Mullard EL-34s, I suppose.

It's not something I'm planning on doing in my lifetime. But the topic came up recently and a debate is now in progress with my science-fiction-slutz friend.

PS, We did discuss operating a vacuum tube in outer space and that no jacket would be needed. But would a filament (or heated cathode) be able to boil-off enough electrons in such extreme cold?

Whatcha think?

[Sammas]

Originally Posted by jabney

If one of the requirements of great tubes is getting a hard vacuum, would manufacturing tubes in outer space make that part of the task easier?

Would the extreme cold make it impossible to get a good seal around the pins? If it would work, would the getter still have to be flashed after the tube was sealed? (I would think so.)

The economics would only work for things like the 300b and re-creations of 1st generation Mullard EL-34s, I suppose.

It's not something I'm planning on doing in my lifetime. But the topic came up recently and a debate is now in progress with my science-fiction-slutz friend.

PS, We did discuss operating a vacuum tube in outer space and that no jacket would be needed. But would a filament (or heated cathode) be able to boil-off enough electrons in such extreme cold?

Whatcha think?

Sure i guess its possible... but the cost vs improvement ratio is probably off the charts. Its most certainly not worth it for the potentially minimal improvement in current manufacted tubes, even if they are recreations of 1st generation Mullards. It costs 10s of millions of dollars to send anything into space...

[Tim Farrant]

I don't have any answers but certainly an interesting line of thought. I have this picture in my head of this robot on the back of a space shuttle assembling vacuum tubes in open space. The logo on the side of the robot says "Manley Labs Inc".



Tim

[KBOY]

Just realized just how tooooooo much I'm a gear geek.

[snoopynow]

There is no extreme cold in outer space- indeed, getting your glass to solidify with only radiant cooling could slow your manufacturing somewhat. Glass blowing might be a little complicated too(you didn't really want to blast off with all that fragile glass prefabricated, did you? And packing for reentry-ugh. No, unless you're intending to use them in the asteroid belt (or whatever) terrestrial vacuum pumps make more sense.

[chriscavell]

Originally Posted by jabney

If one of the requirements of great tubes is getting a hard vacuum, would manufacturing tubes in outer space make that part of the task easier?

No. The hardest part of creating a hard vacuum seal is pumping out the very last bit of atmosphere...not the getting to that point, that's easy for a pump. You'd have to be in deep, deep space. A cheap vacuum cleaner against a balloon will create a more vacant vacuum than most of the space within our solar system.

Also, the calculation of temperature requires integrating over the number of particles in the system. In terms of temperature, it is actually extraordinarily hot in space...there just aren't enough regular collisions between particles for it to be felt as heat.