I need to add a gas/vapor inside a vacuum chamber, but the gas/vapor will condense out at room temperature. Does anyone know of a heated transfer line for high vacuum chambers? This seems like something that should be available but so far I have not found any such item.
What is the substance and the desired flow rate?
I see three solutions:
a) Fabricate a flange. Take a KF stainless stub and cap it with thin sheet stainless steel (brazed joint). Poke a hole through the sheet steel, and affix a 1/4" stainless tube (soldered joint). The 1/4" tube has minimal heat transfer to the flange's O ring (in this case) and can carry LN2 or heated fluids without icing up or knackering your vacuum joint.
b) Deliver the substance as a liquid to a proportional vacuum-rated valve (we use Parker) inside the chamber. Apply heat to the exhaust from the valve - and a crude dosing system is the result.
c) Transfer as gas - only viable for CF joints which can be heated somewhat - heater-tape around the line to the CF flange. And you may have to heat the flange too :( the safety of doing so all depends on the liquid of interest.
eg.
https://www.vacom.de/en/products/heating-solutions/cf-flange-heaters/441-cf-heating-jackets
James, thank you for your suggestions. I am conducting matrix-isolation experiments with PAHs (polycyclic aromatic hydrocarbons). In order to co-deposit them (matrix-isolate) with argon, they need to be heated to their sublimation temperature (anywhere from 50 C to 400 C). Typically this hasn't been a problem, as the tube containing the PAH is mostly outside the vacuum chamber and the distance from the end of the PAH containing tube (side of the vacuum chamber) is relatively short to the deposition surface. However we are in the process of building a new vacuum system and the distance between the chamber wall and the deposition surface will be increased.
The design could be left unchanged, but I am concerned with the expansion of the PAH vapor once it exits the tube. So I am looking at extending the heated tube into the chamber. If the tube was extended into the vacuum chamber unheated the PAH would condense out onto the walls of the tube.
:)
I studied the UV degradation of interstellar PAHs and amino acids in Leiden. I deposited them first as thin films onto silicon blanks using a sublimation heater inside the vacuum chamber and monitored the thickness of the film with a DIY interferometer.
arty shot here:
http://bipbip.info/jg/make4.html
Would that be a thought? I can send extensive details.
Paper here:
Garry et al. 2005. Amino acid photostability on the Martian surface Meteoritics & Planetary Science, 40(8)
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