Frank Calma with John Ruhl (project started January 2006)

Magnetic Bearing for Cosmic Microwave Polarimetry

Balloon borne polarimetry experiments such as the BOOMERANG experiment require adjustable polarimetry apparatus with low frictional loss or heat discharge. One such design is to use a bearing containing a half wave-plate polarimeter. Unfortunately, typical mechanical and electromagnetic designs have prohibitive heat costs and characteristic oscillations that are extremely difficult to dampen or remove.

One possible solution to this issue is the use of high temperature superconductors. The use of high temperature superconductors can be self damping, and heat and frictional loss is then only a result of eddy currents.

The purpose of this project will be to design, build and test a 6” superconducting magnetic bearing. The bearing will be designed to rotate a 10 kilogram mass at a 20 Hz. operating frequency, with the intent to achieve a coefficient of friction m <10 6 , and adequate damping and stiffness to oppose vibration.