Considerations on a Cost Model for High-Field Dipole Arc Magnets for FCC

In the frame of the European Circular Collider (EuroCirCol), a conceptual design study for a post-Large Hadron Collider (LHC) research infrastructure based on an energy-frontier 100 TeV circular hadron collider [1]–[3], a cost model for the high-field dipole arc magnets is being developed. The aim of the cost model in the initial design phase is to provide the basis for sound strategic decisions towards cost effective designs, in particular: (A) the technological choice of superconducting material and its cost, (B) the target performance of Nb$_{3}$Sn superconductor, (C) the choice of operating temperature (D) the relevant design margins and their importance for cost, (E) the nature and extent of grading, and (F) the aperture’s influence on cost. Within the EuroCirCol study three design options for the high field dipole arc magnets are under study: cos − θ [4], block [5], and common-coil [6]. Here, in the advanced design phase, a cost model helps to (1) identify the cost drivers and feed-back this information to the respective magnet designers to make their design as cost effective as possible, (2) compare the optimized design options to each other and make possibly a down-selection of one or two designs. At this stage, we choose to use the cos − θ design option to discuss the main strategic choices. However, the conclusions drawn are equally valid for the other design options. In this paper the results and decisions taken in the initial design phase and the most important cost drivers are discussed.