Estimating the Operating Cost of Superconducting Magnet Systems at Various Operating Temperatures

Cost equations exist for estimating the capital cost of LTS superconducting magnets as a function of stored magnetic energy, magnetic induction times the volume, and, for certain magnets, as a function of overall magnet mass. Cost equations exist for 4.5-K refrigerators and coolers as a function of the cooling at the operating temperature for magnets. One of the arguments for the use of superconducting magnets is a large reduction in the operating cost for the magnet. This report discusses methods for estimating the annual operating cost for magnets. Operating costs include the electricity needed to operate the power supply and the magnet refrigeration system. There are other factors that come into play as well. These include the cost of providing cooling for refrigerator compressors and the power supplies. The refrigeration system maintenance cost can be also important. Operating costs should also include liquid helium, helium gas, liquid nitrogen, and the water that is used to cool refrigerators and power supplies. Methods for estimating magnet operating costs will be presented for magnets that operate at 1.8 to 4.5 K, as well as for magnets that operate at temperatures from 20 to 80 K.