The system performance of the He II refridgeration system used in the
Ebasco team SMES proof of principle experiment is described. The syste
m ultimately achieved a temperature of 1.85 K at a heat load of 37 W,
and ran for 30 h without any problem. System elements requiring specia
l attention, including the heat exchanger design, thermal penetrations
, pumping, and plumbing, are discussed. Operating characteristics invo
lving cooldown, lambda transition, and thermal perturbations are descr
ibed. (C) 1997 Elsevier Science Ltd.