The search of high gradient in superconducting cavities undertaken by the accelerator community over the last few decades has brought tremendous advances. Henceforth, accelerating gradient of about 35 MV/m can be seriously envisaged in the design for the future accelerators, making use of bulk niobium cavities. Nevertheless, the intrinsic sensitivity of such a technology to the radiation pressure usually know as Lorentz force effects, results in a much higher power requirement to maintain constant the accelerating field amplitude and phase in the cavities. Since the pulsed mode has become practically a common specification for the future linacs, Lorentz force effects can build up into mechanical vibrations. Their consequences in the quality of the RF control has also to be investigated. Based on a detailed analysis of RF-mechanical coupling, different technical solutions including stiffening or active compensation will be compared. Amplitude and phase control performances are simulated with a realistic description for the RF components and subsystems, accounting for delays, bandwidth limitation or quantization. |
