Oxford Sigma, in collaboration with Rockwood Cryogenics, a part of The Rockwood Group, is producing a prototype Spherical Tokamak for Energy Production (STEP) Sub‑Scale Model Coil (SSMC) of high temperature superconductor (HTS) to support the UK fusion programme, with the final delivery scheduled later this year. The SSMC represents a key step on the pathway to a future fusion power plant and has been identified as STEP’s first technical milestone of 2026 in the recently published UK Fusion Strategy.
Developed for UK Fusion Energy Ltd (UKFE), the SSMC will enable critical testing of magnet technologies required for the STEP programme. The coil will support dedicated test campaigns to validate magnet performance, thermal behaviour, and structural integrity under conditions representative of fusion operation, helping reduce risk in scaling up to full tokamak systems.
Manufacture of the coil is being carried out by Rockwood as part of a close partnership with Oxford Sigma, combining expertise in advanced fusion materials, precision manufacturing, and cryogenic composite systems. This collaboration reflects the strength of UK industrial capability in addressing the complex engineering challenges associated with delivering commercial fusion energy.
The successful production and testing of the SSMC directly supports priorities set out in the UK Fusion Strategy and underpins progress towards delivery of the STEP prototype power plant.
Dr Thomas Davis, Co-founder and CEO, Oxford Sigma said:
“At Oxford Sigma, we focus on turning fusion strategy into deliverable engineering. Working in close collaboration with Rockwood, this Sub‑Scale Model Coil demonstrates how UK industry can combine materials expertise, manufacturing capability, and system understanding to deliver critical hardware for STEP and the UK Fusion Strategy.”
“The STEP Sub‑Scale Model Coil has allowed Rockwood to bring many years of cryogenic composite engineering experience into one of the UK’s most important fusion programmes. Working closely with Oxford Sigma, we’ve addressed complex manufacturing and integration challenges, and we’re proud to be contributing hardware that supports the UK’s pathway to clean fusion energy.”
“Oxford Sigma and its subcontractor Rockwood are making strong progress towards the UK Fusion Strategy milestone, supporting STEP’s Sub‑Scale Model Coil manufacture and insulation material down‑selection. Rockwood’s advanced manufacturing capability in cryogenic composite systems has been central to addressing complex build and integration challenges, while maintaining a proactive approach to the delivery schedule for testing.”
About Oxford Sigma
Oxford Sigma is a Fusion Technology company with a vision to tackle energy security and climate change by accelerating the commercialisation of fusion energy. Our mission is to deliver materials technology, materials solutions, and fusion design services. Oxford Sigma aims to produce advanced materials technologies, agnostic to fusion approach, for the materials ecosystem. Our fusion core materials are engineered to enable longer term operations for fusion pilot plants, with the aim of roll out to the first-of-a-kind commercial power stations. Oxford Sigma is internationally recognised as a key fusion materials and technological leader.
Get in touch at [email protected]
About Rockwood Cryogenics
Rockwood Cryogenics, part of The Rockwood Group, delivers high-performance cryogenic composite solutions. They specialise in the manufacture of components and assemblies engineered from advanced materials, all destined for demanding, low-temperature applications.
Get in touch at [email protected]
About STEP Fusion
STEP Fusion (Spherical Tokamak for Energy Production) is the UK’s flagship programme to develop a prototype fusion power plant, combining government and industry expertise to deliver clean, abundant energy.
Find out more at www.stepfusion.com