Cryotrap: Advanced Particle Condenser

       The cryotrap is an advanced thermal system designed to condense and freeze gases or particles within a mixture. These gases or particles have a very low partial pressure, meaning that there are very few molecules of the gas within the mixture. 

    The need for a cryotrap occurs when a pure gas becomes contaminated with other gases or particles. The reason for concern is that the pure gas has special properties at certain temperatures and pressures, if it is contaminated, it will not work properly. In this case, the pure substance is Helium gas. Helium becomes a superfluid below 4°K, this means that its thermal heat transfer becomes very high allowing for almost instantaneous conduction between two points. When contaminated, helium fails to become a superfluid. Another concern is the machinery that liquefies the helium. The contaminant particles become frozen at the temperatures needed for helium, when these particles freeze, they begin to block and obstruct the piping, which will prevent the helium from flowing causing system failures.

   The cryotrap developed for the National High Magnetic Field Laboratory provides the contaminant removal that is needed.

   The CPC system does the following:

   1. Helium and contaminants (shown as green) enter the cryotrap.

   2. The helium comes into contact with the copper mesh (indicated in brown). The copper mesh has been cooled by liquid nitrogen (dark blue) to a temperature near 77°K. When the contaminants touch the copper mesh, they freeze out onto the mesh, but the helium continues to flow. This process is similar to how water vapor condenses onto mirrors after a hot shower.

   3. With the contaminants gone, the helium flows on as a pure substance (shown in light blue), where it may be used for other applications.