FLL DRIVING METHOD OF MULTI-CHANNEL SQUID SENSOR SYSTEM FOR AUTOMATING OPERATIONS OF DOUBLE RELAXATION OSCILLATION SQUID SENSOR AND METHOD FOR OBTAINING OPTIMUM BIAS CURRENT

摘要

PURPOSE: An FLL(Flux Locked Loop) driving method of a multi-channel squid sensor system and a method for obtaining an optimum bias current are provided to acquire rapidly a signal in comparison with a manual method by automating an operation of a squid sensor. CONSTITUTION: The external magnetic field is increased in a constant interval Φ0/4. A maximum value and a minimum value of output voltages are obtained by reading output voltages at four points. A voltage change width and a mean voltage are calculated thereby. A mean voltage value is inputted into an offset bias voltage value in order to set the mean voltage value as a reference point of an integrator. The external magnetic field is finely increased in a constant interval Φ0/16 in order to detect a flux point where voltage is increased from minimum. A flux bias generation voltage value is set by adding a predetermined difference to the rising flux point and an FFL is operated.