5th IWC-HTS International Workshop on Cooling Systems for HTS Applications

Heat pipe to interconnect cryogenic cooling circuits in a nuclear fusion machine

27 Oct 2026, 15:00

15m

Waaier (University of Twente)

Oral Novel Cryogenic and HTS Technologies Oral Session - Novel Cryogenic and HTS Technologies I

Speaker

Dr Vicente Climente-Alarcon (United Kingdom Atomic Energy Authority - UKAEA)

Description

Viable nuclear fusion reactors will need to gather in a constrained space a wide variety of elements related to the fuel cycle, and plasma initiation, shaping, and positioning, amongst others. Tokamaks rely upon several sets of coils for plasma control [1]. The large currents circulating through those magnets make the use of superconductors advantageous. For practical purposes, superconductors offer no electrical resistance under constant current conditions; however, this assertion does not hold when current, magnetic field, or both, vary. In a Tokamak, toroidal field coils operate at nearly constant condition to provide a circumferential containment field, whereas the poloidal field ones must accommodate some pulsing mode to exerting its function of plasma initiation, shaping, and control [2]. These dissimilar functions and related performances are translated into different sets of requirements for their corresponding cryogenic systems. Hence, the common approach has been to design several independent cryogenic circuits [3]. In this regard, this contribution will present a cryogenic thermal bridge for connecting the cryogenic circuit of poloidal field coils to the cryogen return of the toroidal field ones. The thermal bridge would be constituted of copper heat pipes filled with a small quantity of either hydrogen (protium, deuterium), neon, or a mixture of them, which suffer a phase change around the expected temperature of operation of the HTS magnets (20 K – 30 K) [4]. In the proposed configuration, those heat pipes act as thermal diodes, evacuating the extra heat produced in the transient operation of the poloidal field coils to the cryogen return of the constant operated toroidal field ones, while preventing the heat flow in the contrary sense. This would increase the pulsing duty cycle of the poloidal field coils while saving space, especially scarce in locations around the inboard side of the vacuum vessel.