Precision Current Transductor for the Fermilab Booster Magnet Power Supply

The Fermilab Booster synchrotron requires precise injection and extraction field regulation (±0.001% repeatability). To achieve this tolerance with a current regulator requires that the current measuring device have a high degree of resolution, stability, and a high output level. To meet this criteria, a transductor using the second-harmonic magnetic modulator technique was chosen. This device is capable of better than ±0.001% measurements from dc to 15 Hz for currents from 50 to 1200 A. Small signal (~100 A peak-to-peak) response is 3 dB down at 10 KHz. The conversion gain was chosen as 1 V/121.25 A to permit operational amplifier compatible signal levels at the output.