MEISSNER EFFECT TORSION SUSPENSION

The first tests of a Meissner effect torsion suspension consisting of a hollow superconducting sphere suspended above a circular superconducting coil have yielded torsion coefficients comparable to or softer than those of 25 μm (0.001 in.) fibers of the type commonly used in gravitation experiments. Data show anomalous behavior which can be attributed to trapped flux. This has at least two effects: it stiffens the torsional restoring torque and it causes a torque about an axis which is oblique to the desired vertical axis. External Helmholz coils modify this by providing compensation for axial asymmetry to reduce the torsion coefficient by a factor of 5 in these experiments. Methods to separate and evaluate the various effects are presented. With improved leveling and field-free cool down in future experiments it is likely that much larger torsion reduction factors will be reached.