| 摘要 |
PURPOSE:To reduce heat and noise to be generated by a probe coil and to prevent the intensity of a signal, which is received by the probe coil, from being lowered by preparing a freezing mixture vessel for probe coil cooling and providing the probe coil, which is made of a superconductor, in this vessel. CONSTITUTION:A high temperature superconductor is used as the material of a probe coil 1 and nitrogen is used as the freezing mixture. Then, as a freezing mixture vessel 3 for probe coil cooling, a tube 2 to have heat insulating walls, which can circulate the freezing mixture, is prepared with being matched to the shape of a probe. Then, the probe is passed through this tube. In case of SQUID to be operated at a nytorogen temperature, the freezing mixture vessel is shared for probe coil. Then, in case of operation in liquid helium, a liquid helium vessel 80 is set in the liquid nytorogen vessel 70, which supplied the liquid nytorogen to the tube 2 for freezing micture circulation. Then, an SQUIDIO, and input coil 20 and a variable resistor 30, etc., are immersed in this liquid helium. Thus, the thermal noise can be reduced and an MRI signal can be received with high sensitivity. |
