A physics based control system for the Duke storage ring
At the Duke FEL Lab, we have developed a new storage ring control system in terms of the physics quantities of the accelerator. Instead of controlling power supply currents in Amperes, this system controls the effective focusing of magnets. By directly controlling the physics quantities, this control system allows tighter integration of the physics model based high level controls with the EPICS based low-level controls. EPICS events have been extensively used to provide time synchronization during the energy and lattice ramping. This new control system also facilitates the implementation of multiple functions on shared control channels. As a result, the physics based control system simplifies many complex control tasks, improves the beam stability during ramping, and facilitates machine studies. With better understanding of the accelerator, it is possible to fine tune this control system to present users with a virtual accelerator whose operation is independent of the ring energy.