WP4 – Superconducting Thin Films for RF Cavities

WP4 on Superconducting TF for SRF cavities

WP1 – Project Management and Coordination

WP2 – Strategic Communication, Outreach and Sustainability

WP3 – Reinforcing Co-creation with Industry

WP5 – Laser Driven Acceleration

WP6 – Advanced RF Technologies

WP7 – Permanent Magnets

WP8 – High-Temperature Superconducting Magnets

WP9 – High-Brightness Electron Injectors

WP10 – Surface Treatments for Niobium SRF Cavities

WP11 – Additive Manufacturing

WP12 – Advanced Materials for Accelerators

The objectives of WP4 is to develop and validate a novel class of SRF cavities made using thin-film coatings, operated in a horizontal cryostat and conduction cooled by compact cryocoolers. Specific objectives:

design and fabricate high quality factor (high-Q) SRF cavities made of copper, coated with Nb₃Sn, and optimized for operation at 4.2 K;
demonstrate stable, efficient conduction cooling using commercially available cryocoolers, thus eliminating the need for liquid helium infrastructure;
integrate and test these cavities in a horizontal cryomodule suitable for industrial, medical, and scientific accelerator applications;
assist industry in equipping its manufacturing lines with a new industrial facility for cavity coating.

This WP evolves 4 Tasks:

Task1: Strategy and Industrialisation

The objectives for this task are:

Develop a long-term strategy to transition TF-SRF technology from R&D to industrial level, targeting higher TRLs and future use in accelerator applications across science, health, and industry.
Industrial partners will help identify current challenges and explore solutions for the industrialisation of TF-SRF cavity production.
The Task will organise an International TF-SRF workshop, participate in relevant conferences sessions, and support meetings to coordinate academia and industry efforts toward European TF-SRF industrialisation strategy.

Task 2: Horizontal cavity integration and RF tests

The goal of this task is to integrate the Nb₃Sn-coated cavity from Task 3 into a cryostat and test it under beam-relevant conditions. Two main challenges must be addressed: (a) replacing a liquid helium cryoplant with conduction cooling, eliminating the need for a helium tank and enabling a simpler setup than 1.8 K modules, and (b) using couplers positioned off the beam axis while maintaining adaptable input coupling. For industrial use, such as compact CW modules, conduction cooling via cryocoolers is preferred over cryoplants.

*Horizontal SRF testing facility Hobicat at HZB*

*Vertical SRF Testing facility at UKRI: cryostat and cryogenic insert*

Task 3: 1.3 GHz cavity production and coating

The main objective for this task is to provide Task 2 with single cell 1.3 GHz copper cavities integrated with power coupler and pick up ports. These cavities will be coated with Nb3Sn thin films. Superconducting TF coating will be performed at CEA, INFN and STFC to explore different coating set-ups and mitigate the risk. Zanon will equip itself with a new industrial facility for cavity coating, based on the experience gained by academic partners in IFAST. Coating systems and set-ups will be optimized to deposit the power coupler and pickup ports doors in addition to the cell.

*A seamless 1.3 GHz cavity made of copper produced by Picoli (on the left) and equipped with flanges at INFN (on the right).*

*PVD facilites for 1.3 GHz cavities at INFN (on the left) and UKRI (on the right).*

Task 4: Superconducting thin film development

The goal of this task is to develop cylindrical sputtering targets for Task 3, new high temperature stable substrates for Nb₃Sn deposition and continue superconducting thin films R&D and post thermal treatments.

Superconductor critical temperature measurements with resistive and magnetic techniques at UKRI