REDUCING THE MAGNET SWITCHING TIME FOR AMS AT PRIME LAB

At the Purdue Rare Isotope Measurement Laboratory, we are cycling magn ets to obtain isotope ratios. Minimizing cycle time increases the prec ision of those measurements. The magnet change time is a significant f raction of the total cycle time since the magnets must be steady to wi thin a few hundred ppm before measurements can begin. PRIME Lab's goal was to obtain isotope ratios to a precision of 1% or better given suf ficient counting statistics. A conventional PID controller was impleme nted, This reduced the magnet switching time for the injector magnet b y approximately 50% and the analyzer magnet by approximately 10%. A du al controller was then implemented. The dual controller consists of an optimization algorithm, called the settling-time optimizer, and a fuz zy logic controller The settling-time optimizer reduces the settling-t ime with every cycle based on the history of previous cycles and the f uzzy logic controller compensates for any disturbances in the system. This controller gave a much better performance by reducing the switchi ng times for both magnets by approximately 75%.