Dynamically tuned high-Q AC-dipole implementation

AC-dipole magnets are typically implemented as a parallel LC resonant circuit. To maximize efficiency, it’s beneficial to operate at a high Q. This, however, limits the magnet to a narrow frequency range. Current designs therefore operate at a low Q to provide a wider bandwidth at the cost of efficiency. Dynamically tuning a high Q resonant circuit tries to maintain a high efficiency while providing a wide frequency range. The results of ongoing efforts at BNL to implement dynamically tuned high-Q AC dipoles will be presented. INTRODUCTION Work on a new spin flipper for RHIC (Relativistic Heavy Ion Collider) incorporating multiple dynamically tuned high-Q AC-dipoles has been developed for RHIC spin-physics experiments. A spin flipper is needed to cancel systematic errors by reversing the spin direction of the two colliding beams multiple times during a store [1]. The spin flipper system currently consists of four DC magnets and three AC-dipoles and will go to five ACdipoles. Multiple AC-dipoles are needed to localize the driven coherent betatron oscillation inside the spin flipper. Having multiple AC-dipoles that require precise control over amplitude and phase makes it necessary to implement them as dynamically tuned high-Q resonant circuits. One of the major challenges was to design of a new magnet and the proper topology to drive it. The topology is required to be both efficient and serviceable.