Operating experience with the Grenoble Hybrid Magnet system

The Grenoble Hybrid Magnet produces fields above 30 T in a room temperature bore as big as 50 mm in diameter. It uses superfluid technology and a polyhelix insert. The authors give the main characteristics of this magnet and describe the operating conditions under which the system is run for scientific use. Only a few modifications have had to be introduced since the magnet became operational in 1986. The resistive part has been subject to two technical improvements to increase water flow and reduce operating temperature, and a fast data acquisition system was added to analyze quench behavior. The superconducting magnet quenched twice and showed a behavior exactly as calculated. No deterioration has been observed in spite of the high discharge voltage of 2.5 kV. The cryogenic system has proven to be quite reliable except for a few problems with the liquefying system and a clogged filter in front of the 1.8/4.2-K heat exchanger.>