A Reliable, Compact, and Inexpensive Klystron for the International Linear Collider

The proposed International Linear Collider (ILC), a tool for future high energy physics research, places unprecedented demands on the high-power radio frequency (RF) system used to drive the accelerator structures. Even small improvements in system cost, power efficiency, or reliability could lead to dramatic cost savings over the life of such a collider facility. This project will design an inexpensive, compact, low-voltage, RF klystron tube, with adequate power for driving a single, ILC one-meter-long structure. The device should provide an operating voltage of 36 kV, an output power of 800 kW, and efficiencies greater than 65 percent. Such a tube would simplify the ILC¿s modulator design as well as its high-power RF distribution network. In Phase I, the tube design was optimized using electrostatic simulations for the gun region and a one-dimensional model for the cavity section. Then, design geometry was fully simulated with a 2½-dimension, electromagnetic particle-in-cell code; analyzed for stability; and optimized for low production cost, small physical size, and easy maintenance/interchange. The simulations predicted an energy conversion efficiency greater than 65%. In Phase II, engineering drawings will be made, and critical components (such as the cathodes, output window, permanent magnets, and ceramics) will be acquired. The klystron will be conditioned and tested with the help of Fermilab personnel and then made available for use within that program. Commercial Applications and other Benefits as described by the awardee: The proposed tube should be useful in a wide variety of particle accelerator applications. In particular, there is a need for such a klystron for the ILC testing program at Fermilab. Its small size and cost also could enable some new uses of RF and accelerator technology in defense, medicine, and industry.