Abstract
Cool down processes of superconducting magnets combined with refrigeration systems are considered. Cool down time may be important in operation of superconducting magnets.
It is shown that cool down time is calculated by a few parameters which are weight of magnets, heat inputs to magnets, efficiency of heat transfer between magnets and cooling fluid, and power of refrigeration systems. Graphical charts to estimate cool down time immediately are represented as a result of the calculation.
Refrigeration systems are as follows: from ambient temperature to near 90°K cooling by helium gas cooled by liquid nitrogen, afterwards to near 20°K helium gas refrigerators are used, finally liquid helium is transferred to vessels of magnets.
