Preliminary Design of a 704 MHz Power Coupler for a High Intensity Proton Linear Accelerator

High intensity proton linear accelerator R&D program is in progress in France. The high energy part of such a linac uses superconducting accelerating cavities with two differ-ent beta sections, 0.47 and 0.65. Each cavity is fed with 704 MHz radio frequency power through one coupler. The goal is to transmit power up to at least 300 kW with a very high duty cycle (up to CW operation) and with a very high reli-ability. Under these conditions, RF windows are subject to thermo-mechanical stresses and potentially to multipacting discharges. The coupler design should minimize the risk of window failure and, should the window break, avoid fatal consequences for the cavity. This paper presents general design considerations, and the preliminary design of some coupler parts.