Technique for observing magnet normalcies

The availability of a continuous fast responding linear liquid level indicator! has made possible the measurement of fluctuations of the surface of a liquid helium bath. Liquid level fluctuations can be caused by such things as mechanical vibrations, thermoacoustic oscillations, boiling effects due to constant and nonconstant heat leaks, dewar pressure changes, and normal state transitions in superconducting magnets. Observation of changes in the liquid surface is particularly important in large superconducting magnet dewars where one needs as many clues as possible to indicate the statue of the magnet and cryogenic system. This paper gives some information about the detector and level fluctuations in helium which may be useful to others.