Operating Experience with the Grenoble Hybrid Magnet System

The Grenoble Hybrid Magnet is the first and only continuous magnetic field device that produces fields above 30 T in a room temperature bore as big as 50 mm diameter. It was also the first system to apply superfluid technology and to use a polyhelix insert. We 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.