That looks like a Bayard-Alpert type, high vacuum ionization gage tube. The smaller glass tube gets inserted into a compression seal to the vacuum chamber, with the tip cut off. The heater/filament causes any gas near it to ionize, and produce a small ion current to the small central wire to be measured.
This could be called a P-type tube, since ions form the current with a negative voltage plate. Not too practical except for the intended use. You need a vacuum pump to evacuate it besides. I don't think it comes pre-evacuated, so running the heater will cause it to burn up. The sealed tip is just to keep dust and moisture out until use.
This could be called a P-type tube, since ions form the current with a negative voltage plate. Not too practical except for the intended use. You need a vacuum pump to evacuate it besides. I don't think it comes pre-evacuated, so running the heater will cause it to burn up. The sealed tip is just to keep dust and moisture out until use.
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