design of compact high power rf components at x-band

In this note, designs of compact high power X-band RF components are presented. Their scaling to C-and S-band is straightforward and in many case could solve a problem of size encountered in previous designs. Geneva, Switzerland 17th May 2016 CLIC – Note – 1067 Design of compact high power RF components at X-band Alexej Grudiev, CERN Abstract In this note, designs of compact high power X-band RF components are presented. Their scaling to Cand S-band is straightforward and in many case could solve a problem of size encountered in previous designs.In this note, designs of compact high power X-band RF components are presented. Their scaling to Cand S-band is straightforward and in many case could solve a problem of size encountered in previous designs. Introduction CLIC stands for Compact Linear Collider. Its compactness is reflected in many subsystem and components. For example, in the main linac practically everything must be compact and there the proposed components have already been used or could be used in the future modifications. Moreover, with the arrival of Toshiba 6MW X-band klystrons on the market an RF unit becomes more compact. This raises the need for more compact RF components. Furthermore, combining these lower power RF units requires more RF components. This makes more compact RF components even more desirable. In addition, scaling solutions proposed below to Cand S-band is straightforward and results in smaller size components which might be a great advantage at lower frequencies. In this note, the RF designs of several compact RF components are given including hybrids, rotating circular TE11 mode launcher, variable phase shifters and attenuators as well as a circular TE11 mode launcher with variable polarization. Compact E-hybrids The compact hybrid presented in Fig 1 has been designed in 2010 for feeding X-band power from one PETS to two accelerating structures (AS) forming a SuperAS for CLIC CDR. It has actually been build and it is in high power operation in CTF3 CLEX. It is called an E-hybrid since the RF power splitting is done in the plane which is tangential to electric field. All four ports are WR90. The Sparameters are presented in Fig 2. Fig 1. E-hybrid for CLIC SAS: geometry and E-field distribution at 1 W input power. Fig 2. S-parameters of E-hybrid for CLIC SAS. An alternative new design is presented in Fig 3. It is different from the CLIC one in the way it splits the power. In the new design the two outgoing power branches exit in the same direction. As can be seen from Fig 3 it is even more compact and from Fig. 4 it has larger bandwidth. Table 1 summarizes the main RF parameters of both designs. Fig 3. New E-hybrid: geometry and E-field distribution at 1 W input power Fig 4. S-parameters of the new E-hybrid. Table 1. RF parameters of CLIC E-hybrid and the new E-hybrid. CLIC E-hybrid New E-hybrid Bandwidth at -30 dB [MHz] [MHz] S11 187 312 S12 187 311 1-2Conversion 220 Maximum Surface Fields at 100MW input power E [MV/m] 34 43 H [kA/m] 91 76