| 摘要 |
PURPOSE:To obtain a uniform magnetic field by preparing a spool on which a superconductive coil is wound and a vessel, in which a cryogenic liquid is stored, by austenite group stainless steel, permeability thereof is specified. CONSTITUTION:An elecrromagnet used for a superconductive nuclear magnetic resonance device for photographing a tomogram for the human body is constituted by a spool on which a super conductive coil is wound and a vessel in which a cryogenic liquid is stored. In this case, these spool and vessel are prepared by austenite group stainless steel, and a composition of the austenite group stainless steel and deposited metals is prescribed so that permeability in field strength of 0.5 tesla at 4.2 deg.K is brought to 1.01 or less. That is, the materials of not more than 0.08% C, 0.1-1.5% Si, 1-10% Mn, 9-17% Ni, 17-25% Cr, 0.5-3% Mo, not more than 0.2% N and Fe as the remainder, which are all represented by wt% are used as mother materials for the stainless steel. The materials of not more than 0.1% C, 0.1-0.5% Si, 5-10% Mn, 12-17% Ni, 17- 19% Cr, 0.5-3% Mo and Fe as the remainder are employed as the deposited metals. |
