The measurement of small magnetic fields near a rotating superconductor
King, Creston A
Rorschach, Harold E., Jr.
Master of Arts
It was predicted by F. London that a superconductor rotating with angular velocity would produce a magnetic field, H, in its interior given by H =2mc / e. Order of magnitude calculations indicate that for speeds of 1000 radians/ second the resulting magnetic field is about 10-4 gauss. This field has never been experimentally observed although attempts have been made.2 In this investigation we are concerned first with rotation at high speeds, second with the problem of a detection system capable of measuring 10-4 gauss, and third with a measurement of the dependence of the London field on the rotational speed. We have chosen to use mechanical rotation since it is simple and eliminates the problem of unwanted magnetic fields encountered in a magnetic suspension and rotation scheme. Two separate detection systems have been evaluated, both depending on the flux changes produced by a rotating superconductor.