Abstract
This paper continues from part-1 to study on the cooling of superconducting magnets by the use of He II. In this part, the fact that the cooling efficiency in He II increases drastically by pressurizing the liquid is illustrated by examples. We also give examples in which the performances of magnet quenching currents and minimum propagating currents were improved by He II. On the other hand, we envisage several problems of instability on the lowered temperature region, such as the Kapitza resistance between the stabilizing material and the superconductor, and the a.c. loss caused by increased magnetization. The demerits, however, are probably overcome by the excellent cooling abilities of He II, especially of the pressurized He II. Finally, basic ideas of conceptual designs of superconducting troidal field coils in Torus II Supra (France) and NUMAK (U.S.A.) projects are introduced focusing on the cooling manner by means of the subcooled He II at 1.8K.
