The Impact of Protection Heater Delays Distribution on the Hotspot Temperature in a High-Field Accelerator Magnet

Quench protection is one of the challenges in the development of high-field superconducting magnets for future particle accelerators, such as the High-Energy and High-Luminosity LHC. The protection of the accelerator magnets up to now has relied on protection heaters to spread the normal zone across the winding, thus increasing the magnet resistance. The design of the protection heaters layout largely deals with the optimal positioning of the available heater energy on the coil surface. The aim is to quickly bring a large fraction of the winding to resistive state and induce a fast current discharge. Since the coil consists of different field regions, different approaches for heater energy distribution can be considered. Possible optimization criteria can be, for example, the minimum average delay in all the coils, the minimum first delay, or the minimum last delay. In this paper, we present a study of the impact of heater delay distribution on the resulting current decay and hotspot temperature. We use our newly developed current decay model to simulate the magnet current decay rate for different heater designs. We consider the case of the LARP-CERN MQXF magnet, being developed for the LHC luminosity upgrade.