On 31 July 2026, the IFMIF/EVEDA Project completed the first warm-conditioning period for the eight power couplers of the LIPAc Superconducting Radio-Frequency (SRF) Linac. This advances the fully integrated accelerator towards its first cooldown and subsequent beam commissioning.
Warm conditioning began on 10 June as an essential step before operation at cryogenic temperature. The power couplers carry radio-frequency (RF) power from the sources to the eight superconducting cavities that will accelerate the beam. At room temperature, power is raised gradually while the team monitors vacuum, temperature and electrical discharges, and verifies the control and protection systems.
The LIPAc SRF Linac during warm conditioning preparation activities at Rokkasho.
During this first period, four of the eight couplers reached individually continuous-wave operation between 25 and 32 kW, exceeding the 20 kW objective presented at Project Committee #37. Three more underwent useful conditioning or testing, so progress was achieved on seven of the eight couplers.
These results provide an important preparatory validation of the SRF Linac’s RF power delivery and control systems. When powered, multipacting can occur, then electrons repeatedly strike internal surfaces, releasing more electrons and temporarily limiting power transmission. Controlled conditioning progressively reduces this effect, allowing the couplers to reach stable operating conditions.
Continuous-wave operation means sustained power rather than short pulses. Progress on three other couplers strengthens confidence in completing the campaign and proceeding to cooldown. Validation at cryogenic temperature and with beam will follow.
The second warm-conditioning period, scheduled to begin in October, will provide approximately the same conditioning time to complete the remaining couplers and consolidate the results already achieved.
RF experts monitoring the warm conditioning of the LIPAc SRF Linac power couplers.
This milestone is another important step in the LIPAc roadmap, reflecting close coordination among the Integrated Project Team, contributing institutes and contractors. The IFMIF/EVEDA Project thanks all Contributing Institutes and Contractors for their commitment and responsiveness.