A continuous-wave superconducting linear accelerator scheme for the drive beam acceleration of the Compact Linear Collider

The Compact Linear Collider (CLIC) utilizes two 2.5-km-long normal-conducting linear accelerators (LINACs) to produce a drive beam with 140μs pulse length at a repetition rate of 50 Hz. This setup is relatively expensive in the early stages due to both the length of the drive beam LINACs and the amount of the power sources for one drive beam complex are the same in all energy stages. A new concept of accelerating the CLIC drive beam in superconducting LINACs as an alternative scheme is investigates in this work. This scheme requires a minimal number of power sources at the early stages of the CLIC and consequently has the potential to reduce the entry cost. A dimensionless parameter named capacity factor η which determines the number of the superconducting structures and the power is introduced. Two proof-of-concept schemes to compensate the beam-loading effect are also proposed in this paper. The mixed-structure scheme finally selected as the nominal design achieves an optimum η of approximately 1.16 compared to a value of 50.5 without the beam-loading compensation. A rough estimation on the cost of this scheme has also been studied.