We can detect the indication of failures and prevent equipment from becoming damaged through visually monitoring the state inside cryogenic equipment. We investigated use of a flexible fiberscope as an endoscope. We also investigated use of a web camera owing to its low cost. We selected a flexible fiberscope without the function of remote control because of the lower heat invasion and higher voltage insulation. We set the fiberscope inside the cryogenic equipment using a rubber stopper to hold the vacuum. We confirmed that the inside was observable even for objects cooled to approximately 20 K. As for the web camera, we confirmed that it could be satisfactorily used adjusting the temperature to approximately 200 K under a high magnetic field of 5 T.
The Great East Japan Earthquake, which occurred on March 11, 2011, damaged a superconducting NMR magnet installed in the National Institute for Materials Science (NIMS) in Tsukuba, Japan. We have developed an instrument to visualize a material cooled in cryogenics to repair the magnet. A temperature controlled video scope works well in a helium gas environment and in the vicinity of a liquid helium surface. The instrument enables us to monitor the situation of a material in a low temperature state. Utilizing the instrument, we have succeeded in recovering the electric contact of an electric socket of a superconducting magnet covered with the contaminant of solid air. The socket was dug out using a drill while conducting monitoring using the instrument. Behaviors of solid air in cryogenic instruments for an injection of a helium gas were also visualized.