A FIBER OPTIC MAGNETIC FIELD SENSOR

THIS PROJECT WILL DEVELOP A FIBER OPTIC PROBE FOR MAGNETIC FIELD MEASUREMENTS ON TOKAMAK EDGE PLASMAS. THIS PROBE ALSO WILL BE USEFUL FOR ALL LABORATORY PLASMAS WITH SELF-GENERATED MAGNETIC FIELDS, FOR SATELLITE MEASUREMENTS, AND IN POSSIBLE MEDICAL APPLICATIONS. THE INITIAL PROBE WILL BE SENSITIVE TO 0 B 200 GAUSS WITH A 0.1 GAUSS SENSITIVITY (WHICH CAN BE EXTENDED IF NEED BE). THE RESPONSE WILL BE FLAT FROM DC TO 1 GHZ. THE DEVICE WILL BE SMALL (1 MM DIAMETER) AND THEREFORE NON- PERTURBATIVE. IT IS DESIGNED TO WITHSTAND STEADY STATE TEMPERATURES OF 400 DEGREES CENTIGRADE IN VACUUM. THE HEART OF THE SENSOR IS A DILUTE MAGNETIC SEMICONDUCTOR CRYSTAL THAT EXHIBITS HUGE FARADAY ROTATION. SINCE THE PROBE IS COMPLETELY OPTICAL, IT IS IMMUNE TO THE AMBIENT ELECTROMAGNETIC SIGNALS THAT USUALLY SURROUND MOST PLASMA PHYSICS EXPERIMENTS. THE OPTICAL OUTPUT SIGNAL CAN BE TRANSMITTED TO A REMOTE DATA ACQUISITION SYSTEM WHERE IT IS CONVERTED TO A VOLTAGE AND DIGITIZED.