Experiments with Supersonic Beams as a Source of Cold Atoms

500 l/s Turbo Pump
Supersonic Nozzle
70 l/s Turbo Pump
Skimmer
Locations
Figure 5.14: A CAD image of the hydrogen valve chamber and differential pumping
chamber. The nozzle hangs from the pool type cryostat in the center of the 8 inch
cross. The chamber on the right provides differential pumping.
of these latter chambers is low enough that without differential pumping, the gas load
from the supersonic beam would build up in these chambers, decreasing the mean
free path and trap lifetime. A CAD drawing of the valve chamber and differential
pumping chamber can be seen in figure 5.14.
The slowing and trapping chamber consists of two parts, the coilgun tube
and the trapping cross. The coilgun tube has two titanium 1.33 inch conflat flanges
separated by a 22.0cm grade 5 titanium tube. The tube has a wall thickness of .38mm
and an outer diameter of 9.52mm. The reason this titanium alloy is chosen is its high
electrical resistance which reduces the eddy currents caused by the coil, coupled with
its lack of magnetism and good vacuum properties. The coils are wound around the
tube, with the center of the first coil sitting 43.44 cm from the nozzle. This chamber
has 15 of the 18 coilgun coils wound around it (the last three coils are wound around
the trapping chamber). A CAD image of the slowing and trapping chamber, with the
coils, is shown in figure 5.15 and a photograph of the assembled chamber with the
coils is presented in figure 5.16.
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