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Description
High-efficiency klystrons can significantly reduce the operational costs of particle accelerators. For the low-duty-factor klystrons commonly used in linear accelerators, however, the power consumption of electromagnetic focusing coils remains non-negligible. This work presents the progress of an S-band 50 MW high-efficiency klystron with periodic permanent magnet (PPM) focusing, aiming at high conversion efficiency while minimizing auxiliary power consumption.
Because of the relatively large dimensions of S-band tubes, the focusing structure is constrained and the beam rigidity is limited. These factors impose stringent requirements on the beam-dynamics design and require coordinated optimization of the magnetic-field configuration and the electron bunching process. Three-dimensional PIC simulations give an output power of 51.2 MW and an efficiency of 53.8%, with no reflected electrons. The overall tube length is 1310 mm.
The proposed S-band PPM klystron provides a promising approach for improving the efficiency and reducing the operational cost of high-power RF sources in accelerator applications.
