The Levitated Ring in FM-1

The design and tests of the 60 inch diameter superconducting ring and Dewar assembly are described. The ring has been successfully levitated in the slide unstable mode in the FM-1 Machine. The magnet, wound of 4221 turns of 90 mil RCA Nb3Sn ribbon, has a current capacity of 375,000 ampere turns. The coil is charged inductively or by external power supply, and is housed in a seven inch minor diameter toroidal Dewar with external connections for filling, venting and charging under high vacuum. Test results of quench temperature vs. current for isochoric life of the ring at full current is approximately one hour. This corresponds to 10.7°K at 25 atmospheres.