| Paper | Title | Page |
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WET2H3 |
Interrelationships and Limits | |
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| For the FCC ee-machine we consider 4 different operation scenarios (Z, W, H, t) with requirements ranging from a high beam current and HOM (Z) to high accelerating gradients (H, t). We investigate the RF system for the 4 machines towards cavity design, material choice and staging scenarios. We built a generic model of the RF system based on the mathematical relationships found in the common accelerator literature describing all relevant aspects, e.g., the amount of RF power or the overall length of the RF installation. These mathematical expressions depend on other quantities which are either fixed design variables or show further dependencies. The mathematical model can be represented as a directed graph allowing to study the impact of each of the design variables on the overall system performance. Furthermore, the model indicates when any of the quantities exceeds assigned limits, e.g., in power consumption. Applying these limitations to the RF model for a wide range of cavity types (number of cells), materials (Nb/Cu or bulk Nb), operating temperatures (2 or 4 K) and wake loss parameters we derive the most suitable parameter range for the two distinct machine layouts. | ||
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WET2H8 |
SRF Material R&D for FCC | |
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| In the context of the FCC study, CERN is re-launching R/D efforts on SRF materials to meet the challenges of a large machine: energy efficiency and investment costs. The focus is put on the development of thin superconducting films on copper substrates. Thin films have been used at CERN for large SRF systems since the LEP time, on to the LHC and now recently in the HIE-ISOLDE linac. In all these applications niobium was the superconductor of choice. Nb/Cu cavities have achieved low surface resistances at the fields of interest, and their potential is not exhausted. Q slope mechanisms are being investigated, with the aim of bringing the high field performance of coated cavities closer to the the level of bulk Nb. In parallel, other superconducting materials, like Nb3Sn and V3Si are studied as a promising alternative to Nb/Cu in the timeline of the study. In this contribution, an overview will be given of the R/D program ongoing at CERN on SRF materials for FCC, and some first results will be presented. | ||
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