| Paper | Title | Page |
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| MOPP093 | Fast L-band Waveguide Phase Shifter | 769 |
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| During the operation of accelerators it is often important to rapidly change the parameters of the RF system, such as cavity resonant frequency, coupling, or electrical length. For this purpose a fast L-band planar phase shifter has been designed, that has advantages compared to the coaxial scheme considered before by the authors (EPAC 06). The phase shifter is based on a new ferroelectric ceramic, whose permittivity changes with application of an external voltage. The switching time depends on only the external HV circuit and can by less than a few microseconds. The conceptual design and electrical parameters of the new phase shifter are presented, as are first results of low power measurements on a 1/3 model. | ||
| WEPP133 | High-gradient Multi-mode Two-beam Accelerating Structure | 2806 |
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A new accelerating structure which is aimed to provide gradient >150 MV/m for next generation of multi-TeV linear colliders is suggested. The structure is based on periodic system of quasi-optical cavities*. Each of these cavities is excited in several equidistantly-spaced eigen modes by the drive beam in such a way that the RF fields reach peak values only during the short time intervals when an accelerating bunch is resident in the cavities, thus exposing the cavity surfaces to strong fields for only a small fraction of time. This feature is expected to raise the breakdown and pulse heating thresholds. The proposed structure embodies most of additional attractive properties: the cavity is an all metallic structure, no transfer or coupling structures are needed between the drive and acceleration channels, the cavity fields are symmetric around the axes of the drive beam and the accelerated beam, the cavity can exhibit high transformer ratio. Calculations of single quasi-optical rectangular cavity with parameters of drive and accelerating beams close to ones adopted for the CLIC project show that high gradient as well as high efficiency are achievable.
*S. V. Kuzikov et al. "Quasi-optical accelerating structure operated with a superposition of synchronized modes," Conf. Digest of Joint 32nd IRMMW Conf., Cardiff, UK, 2007, Vol.2, p.797-798. |