A high-performance magnetic shield with large length-to-diameter ratio

作者：Dickerson Susannah^*; Hogan Jason M; Johnson David M S; Kovachy Tim; Sugarbaker Alex; Chiow Sheng wey; Kasevich Mark A

来源：Review of Scientific Instruments, 2012, 83(6): 065108.

DOI：10.1063/1.4720943

We have demonstrated a 100-fold improvement in the magnetic field uniformity on the axis of a large aspect ratio, cylindrical, mumetal magnetic shield by reducing discontinuities in the material of the shield through the welding and re-annealing of a segmented shield. The three-layer shield reduces Earth's magnetic field along an 8 m region to 420 mu G (rms) in the axial direction, and 460 and 730 mu G (rms) in the two transverse directions. Each cylindrical shield is a continuous welded tube which has been annealed after manufacture and degaussed in the apparatus. We present both experiments and finite element analysis that show the importance of uniform shield material for large aspect ratio shields, favoring a welded design over a segmented design. In addition, we present finite element results demonstrating the smoothing of spatial variations in the applied magnetic field by cylindrical magnetic shields. Such homogenization is a potentially useful feature for precision atom interferometric measurements.

• 出版日期2012-6