REFRIGERANT CIRCULATING DEVICE AND REFRIGERANT CIRCULATING METHOD

摘要

A helium circulating device capable of re-liquefying a refrigerant efficiently at low cost; and a helium circulating method. A helium circulating device (20) comprises a dewar (3) storing liquefied helium at about 4 K, a condenser (40) connected to a GM freezer (22) and serving to re-liquefy helium gas, a first system including a first restoring tube (L10), a cooling tube (L11) and a gas tube (L12) for leading part of the helium gas in the dewar (3) to the freezer (22) and returning the helium gas cooled by the GM freezer (22) to the dewar (3), a second system including a second restoring tube (L20) and a returning tube (L21) for leading part of the helium gas in the dewar (3) to the condenser (40)and returning the helium gas liquefied by condenser (40) to the dewar (3), a heater (41) installed in the condenser (40), and a control unit (100) for controlling the heater (41) according to the in-device pressure in the dewar (3).