SIMULATIONS AND OPTIMIZATIONS OF A NEW POWER COUPLER FOR 3.9-GHZ SUPERCONDUCTING CAVITIES AT FERMILAB*

GHz third harmonic superconducting cavities have been used to increase the peak bunch current and to compensate for non-linear distortions in the longitudinal phase space due to sinusoidal 1.3 GHz accelerating cavity voltage (1). The power coupler is one of the important and complicated components of the third harmonic system for the TTF3 project. From electromagnetic, multipacting, and thermal simulations of the power coupler, optimized designs have been achieved, enabling one to minimize or eliminate potential problems in advance. This paper presents our recent work on simulation and optimization of the power coupler.