Gearing Up to Pump Down

A project log for Glass Tube Solar Thermionic Converters

Thermionic energy conversion isn't very efficient (it's also nothing new) but they *are* photovoltaic devices you can build with a torch

nick-pooleNick Poole 04/25/2022 at 20:120 Comments

These Solar Converters are only a small diversion in the larger project of experimenting with vacuum tube devices at home. To that end, I'm already in the process of building a high vacuum system that will be more than capable of pulling these tubes down to the levels of vacuum required to work. I'm also putting together the glass-working tools that will be needed to fabricate the envelopes and feedthroughs. I thought it would be nice to post some pictures of my growing stack of vacuum equipment here! 

Here you can see my gauge controller and a number of vacuum gauges: two Edwards Pirani gauge heads and a Duniway Stockroom ion gauge. I've also put together a bunch of vacuum plumbing, although like any good plumbing project, I'm still missing some fittings. In the lower left, you can get a small peek of the mechanical vacuum pump that I planned to use. Unfortunately, even though it was sold to me as possibly being a Pfeiffer MVP series pump, it appears to be a Vacuubrand MZ, which I might get away with because of my choice of turbo pump (more on that in a second) but I'm also waiting on another pump to arrive which should reach much more convincing levels of backing pressure. 

The big succboy is an Edwards EX255H compound pump which was pulled from a working mass spectrometer. It came with the controller, so I just need to provide it with 24V and it will do the rest. It has all of the modern self-protection features and tolerates a continuous working foreline pressure up to 5 mbar(!) although I hope to be able to achieve better than that. 

I'll post another project log when we achieve first pump-down. Right now the main hold-up is an ISO-K 100 to KF16 reducer that I had to order from China. In the meantime, I'll be sorting out my roughing pump and plumbing.