To obtain the maximum accuracy from your Cesium clock, there must be no residual magnetic field which could affect the oscillation of the cesium beam. To ensure this, the old Hewlett-Packard applied their legendary over-engineering skills to this de-gausser, which applies a precisely calculated exponentially decreasing alternating magnetic field to coils engineered into the cesium ion tube. The test equipment required for this procedure weighs even more than the atomic clock.
