The construction of the 40 T class hybrid magnet system was completed
at the Tsukuba Magnet Laboratory of NRIM. Now, the total system test i
s being performed. This system consists of a hybrid magnet composed of
a water cooled magnet and a superconducting magnet power supplies for
these magnets, water cooling system, and control system. The power su
pply for the water cooled magnet is a low ripple power supply, and it
also has a ''soft stop circuit'' to prevent quenching of the supercond
ucting magnet. In order to confirm the achievement of low current ripp
le and efficiency of the soft stop circuit, we carefully analyzed the
behavior of this circuit. As a results, we confirmed that the performa
nce Of the power supply satisfies the specifications. Also, we verifie
d efficiency of the soft stop circuit.