Quench detection of superconducting magnet by dual-core optical fiber

We demonstrated that a temperature rise of 1.0 K was detectable at 4.2 K using a dual-core optical fiber. The fiber has two single-mode optical cores in one fiber. Using this technique, we detected a quench of a superconducting magnet by detecting temperature rise due to joule heating caused by normal transition. A quench detector using this optical method is immune from electromagnetic noise, free from troubles caused by break-down of electrical insulator, and has many advantages over a conventional quench detector measuring voltages of a magnet.