Abstract
The linac of the European project Extreme Light Infrastructure-Nuclear Physics (ELI-NP) foresees the use of 12 traveling wave $C$-band accelerating structures. The cavities are 1.8 m long, quasiconstant gradient, and have a field phase advance per cell of $2\ensuremath{\pi}/3$. They operate at 100 Hz repetition rate, and, because of the multibunch operation, they have been designed with a dipole higher-order mode (HOM) damping system to avoid beam breakup. The structures have symmetric input and output couplers and integrate, in each cell, a damping system based on silicon carbide (SiC) rf absorbers coupled to each cell through waveguides. An optimization of the electromagnetic and mechanical design has been done to simplify the fabrication and to reduce the costs. The cavities have been fabricated, and the first full-scale prototype has been also successfully tested at the nominal gradient of $33\text{ }\text{ }\mathrm{MV}\mathrm{/m}$, repetition rate of 100 Hz, and pulse length of 820 ns. It represents, to our knowledge, the first full-scale linac structure with HOM damping waveguides and SiC absorbers tested at this high gradient. In the paper, we illustrate the realization process of such a complicated device together with the low and high power test results.
Highlights
The gamma-ray beam system of the European project Extreme Light Infrastructure-Nuclear Physics (ELI-NP) [1] foresees the use of a multibunch train of electrons colliding with a high-intensity recirculated laser pulse [2], generating an intense source of gamma-ray photons by Compton backscattering
The linac consists of an S-band injector and 12 traveling wave (TW) C-band disk loaded accelerating structures, 1.8 m long, quasiconstant gradient with 2π=3 field phase advance per cell operating at 33 MV=m average accelerating field
As illustrated in Ref. [10], the geometry of the silicon carbide (SiC) absorbers has been strongly simplified with respect to the Compact Linear Collider (CLIC) structures, and they resulted as four tiles inserted in each module
Summary
The gamma-ray beam system of the European project Extreme Light Infrastructure-Nuclear Physics (ELI-NP) [1] foresees the use of a multibunch train of electrons colliding with a high-intensity recirculated laser pulse [2], generating an intense source of gamma-ray photons by Compton backscattering. We present how such complicated structures were realized with showing the detail of the fabrication mostly in the assembly stage, the low and high power test result including tuning, and vacuum measurement results To our knowledge, these cavities have been the first full-scale waveguide damped structures to be tested at such a high gradient [11]. “tiles” with a very simple shape (rectangular type), inserted and fixed in modules of 12 cells Such a design has another advantage from the vacuum conductance point of view, because all cells have a hole form cell to cell in the proximity of the SiC absorber that allows them to have a high vacuum conductance in the proximity of the SiC absorbers themselves (Fig. 2). IV, the results of the high power rf tests will be reported
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
