Experiments with Supersonic Beams as a Source of Cold Atoms

Table 4.1: Peak magnetic fields measured for different lengths of TGG crystal
crystal thickness measured peak B-field
1.40 mm 5.43 T
2.35 mm 5.05 T
5.00 mm 5.14 T
the true volume occupied by the wire is greater than in the finite element calculation,
leading to a lower real current density.
The numerical calculations of the trajectory of a synchronous atom, as well
as Monte-Carlo simulations of the entire beam being slowed by the coilgun, use the
finite element calculations for the spatial profile of the fields in the coils. The temporal
profile is provided by the measurements taken using Faraday rotation.
4.5.3 64 Stage Apparatus and Vacuum Chamber
The finished coils are mounted on an 89.77 cm long aluminum support, which
holds the coils in vacuum. Since the support is machined from a single piece of
aluminum, the coils are aligned to each other to better than 50 μm. The center-to-
center distance between the coils is 14.1 mm. Each coil is mounted in a semi-circular
groove in the support and the coils are clamped in place individually to allow for easy
replacement of a single coil. The system is designed this way because of the problems
encountered with the proof-of-principle experiment, where the coils were not easily
replaceable, and where several coils failed. Improved coil testing techniques have
made individual coil replacement unnecessary to this point, but the system has the
capability for quick repair should it be required.
Vented screws that clamp the coils individually to the aluminum support are
also used in conjunction with a folded piece of Kapton to secure the wires coming out
of the coil. This ensures that the wires are securely held a way that reduces the ease
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