Vacuum Chambers and Environments

To simulate the conditions of interstellar space an ultra-high vacuum (UHV) system is needed. This allows pressures as low as 10^-10 torr to be obtained, corresponding to a mean number density, n(particles) ~ 10¹² m^-3. Although this density is still higher than that found within interstellar dust clouds where n(H₂) ~ 10¹⁰ m^-3 [1], it's as close as can practically be achieved in the laboratory.

The vacuum system comprises of three stainless steel chambers sealed by Conflat flanges. The chambers are all pumped by turbomolecular pumps and the chamber in which the hydrogen recombination will take place is further pumped by a titanium sublimation pump. Furthermore, the two chambers containing the helium cold-heads will also be cryopumped by these devices when they are operated, thus enhancing the pumping speed.

Reference

T.J. Millar, J. Hatchell, Faraday Disc. 109 (1998) 15.

This page last modified 26 October, 2007 by John Edridge