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Sub-task 5: CLIC crab cavity and stabilisation development. This sub-task has two main goals To understand and measure long-term phase stability in high power pulsed RF distribution and amplification, and use this to develop a distribution scheme for CLIC crab cavity
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Sub-task 5:CLIC crab cavity and stabilisation development. • This sub-task has two main goals • To understand and measure long-term phase stability in high power pulsed RF distribution and amplification, and use this to develop a distribution scheme for CLIC crab cavity • To design, evaluate and high gradient test a CLIC crab cavity design. This will involve the testing of cavities developed pre-EUCARD2 and the development of a new cavity.
Main beam outward pick up 12 GHz Oscillator CLIC Crab High Power Distribution • Need to understand long term phase stability of the distribution scheme (thermal and mechanical effects) • Requires an experiment to measure phase transients and assess viability. Can be done parasitically at CERN • Measure klystron transients • Measure waveguide transients • Use this to develop a realistic distribution scheme travelling wave cavity Laser interferometer Control Dual Output or Magic Tee Waveguide with micron-level adjustment Waveguide with micron-level adjustment LLRF LLRF Phase Shifter From oscillator 12 GHz Pulsed Klystron ( ~ 20 MW ) Pulsed Modulator Vector modulation Control main beam outward pick up
CLIC Crab High Gradient Testing Cavities Built but not tested • Cavity 1: UK manufactured, waveguide coupler, test of mid cells • Cavity 2: Elliptical cells and on cell couplers. CERN manufactured. Cavities designed but not built • Cavity 3: Final cavity design with damping waveguides (without loads) Cavities not designed • Cavity 4: Final prototype with HOM loads. • At the end of EUCARD 2 we plan to have designed all 4 cavities and build the first 3. • Also will evaluate wakefields of final design
Sub-task 5:CLIC crab cavity and stabilisation development. • This sub-task focuses on the RF design of the CLIC crab system. The CLIC crab cavities require extremely tight phase stabilization between the two cavities during the beam pulses. In order to ensure both cavities have the same phase it is necessary to drive both cavities from a single klystron. The phase stabilization at the end of two 25 meter long lengths of waveguide will be investigated. An experimental system test will be planned, designed and constructed to fully understand how such a system will operate at CLIC. This task will investigate the phase stability of long lengths of waveguide as well as individual components such as bends and splitters, and will study the transient behavior of high power klystrons. These measurements will be performed parasitically on existing high power tests at CTF3 and on the high power klystrons at CERN. The sub-task will also develop a full structure design, including input couplers, unwanted mode dampers, HOM/SOM loads, and evaluation of this design. During EUCARD an initial design of the cavity has been developed with a basic study of various unwanted mode dampers. A bare cavity prototype without damping was also produced. In this task a complete RF design will be developed considering electromagnetic and mechanical issues. Full 3D electromagnetic simulations of the crabbing mode and higher order modes in the structure will be performed with and without beam to verify the design meets the required tolerances including wakefields. A prototype cavity will be constructed external to this project and high gradient testing of this prototype cavity will be undertaken at CERN utilizing a high power klystron.