| 摘要 |
PURPOSE:To downsize a cryostat for fluxmeters, make it possible to restart measurement after a pause only by replenishing cryogenic media, and reduce noises due to radiant heat shielding material, by forming the portion of a cooling chamber where the measuring probe of a SQUID fluxmeter is housed into a reverse cone shape. CONSTITUTION:The central portion of a cooling chamber 3, that is, the measuring probe housing area 3C connected to the lower part of the cryogenic medium holding area 3B, is formed into a reverse cone shape. In other words, the upper end of the measuring probe housing area 3C has the same diameter as the cryogenic medium holding area 3B, and the diameter is smaller at a lower level. The diameter of the flat bottom 3D of the measuring probe housing area 3C is almost the same as that of the lower end of a measuring probe 19. A step 3E is integrally formed in the area between the bottom 3D and the area where the slope starts; the lower end of a measuring probe 19 will fit in the hole formed by the step 3E. A radiant heat shielding material 23 is placed in the heat-insulating vacuum layer between the inner wall 11 and the outer wall 9 of the bath body 5. |
