The 38^th IFMIF/EVEDA Project Committee (PC#38) met on 27 and 28 October 2026 at the QST Rokkasho Institute for Fusion Energy, Japan.

The Committee congratulated the Project Team, Implementing Agencies, contributing institutes and other contributors on the successful achievement as planned of the 2 key milestones for 2026: completion of the SRF Linac assembly in April and start of warm conditioning in June. It also welcomed the excellent progress in RF conditioning, with six of the eight SRF power couplers reaching continuous-wave operation above the initial power target.

Recognizing these achievements, the Committee reaffirmed its support for the accelerated LIPAc schedule, targeting the 1^st cryomodule cooldown in December 2026 and the 1^st beam through the complete accelerator in March 2027. The Committee also highlighted the importance of LIPAc’s future validation results for IFMIF-DONES and A-FNS developments and acknowledged the remarkable commitment and cooperation of the European and Japanese teams in advancing this ambitious programme.

On 13 October 2026, warm conditioning of the LIPAc Superconducting Radio-Frequency (SRF) Linac power couplers resumed at Rokkasho, starting with coupler #2. The restart took place on the planned date, marking the beginning of the second conditioning period in preparation for the first cryomodule cooldown and subsequent beam commissioning.

The campaign builds on the progress achieved between 10 June and 31 July, when four of the eight couplers individually reached continuous-wave operation at power levels between 25 and 32 kW. The new conditioning period aims to extend this progress to the remaining couplers and consolidate the results already obtained.

Power couplers deliver RF power to the superconducting cavities that will accelerate the beam in a later stage. Warm conditioning prepares these components for operation by gradually applying RF power at room temperature while monitoring their vacuum response, temperatures and discharge activity. This process is an essential preparation step before testing them at cryogenic temperature. Achieving the restart on schedule reflects the sustained efforts and commitment of the whole Integrated Project Team working onsite and offsite. The IFMIF/EVEDA Project thanks all colleagues, contributing Institutes and contractors whose work and commitment made this possible.

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.

On 22 July 2026, Marc Lachaise, Director of Fusion for Energy (F4E), visited the IFMIF/EVEDA Project at QST, Rokkasho. The visit provided an opportunity for discussions with QST management, the Japanese and European teams involved in LIPAc. They discussed its progress, the priorities for the forthcoming commissioning phases, its contribution to IFMIF-DONES and future fusion neutron sources.

During a tour of the accelerator vault, Marc Lachaise saw the superconducting linac and the ongoing preparations for the next major commissioning milestones. His exchanges with team members addressed both the achievements to date and the technical challenges involved in bringing this unique high-current accelerator into operation.

“I would like to praise the work and contribution of the EU team in close collaboration with QST. During my visit and throughout the exchanges with members of the team, I was able to witness the remarkable progress of LIPAc. Thanks to all of you the link between LIPAc and IFMIF-DONES is stronger, connecting Europe and Japan. I would like to congratulate both parties for the exemplary collaboration at the service of the fusion community,” stated Marc Lachaise.

The visit highlighted the firm commitment of all contributors and the value of the long-standing EU-Japan partnership in advancing accelerator technologies for fusion materials research.

On 10 June 2026, just after 14:00, the IFMIF/EVEDA Project reached an important milestone with the start of warm conditioning of the LIPAc Superconducting Radio-Frequency Linac, now integrated into the beam line.

Warm conditioning is an essential preparation step performed at room temperature before operation at cryogenic temperature. During this phase, radio-frequency power is progressively injected into the RF power couplers, while the superconducting cavities are kept detuned. This process allows the couplers and associated RF systems to be gradually brought to their operating conditions under carefully monitoring. This activity began in line with the accelerated schedule presented at Project Committee #37 and marks the first RF injection into the one of the eight power couplers of the integrated SRF Linac. The initial operation progressed well, with this first coupler under conditioning behaving as expected.

During the first RF injections, the team monitored the cavity and coupler parameters through dedicated operator interfaces, including the RF power delivered to the coupler, the reflected power, the vacuum response and the photomultiplier signals. The observed vacuum activity and light signals are consistent with the expected conditioning behaviour, in particular considering that the couplers had been stored under nitrogen for several years after their initial conditioning before assembly.

SRF Linac area being prepared for warm conditioning
The SRF Linac and associated systems were prepared for the start of warm conditioning, following intensive coordination between the Project Team, CEA and QST teams.

Following these encouraging first results, the conditioning campaign is now continuing in automatic mode during the nights, with continuous monitoring provided by the QST contractor. This allows the conditioning process to progress efficiently while maintaining the required level of operational supervision.

The successful start of warm conditioning represents a significant step forward in the preparation of the forthcoming beam commissioning activities and confirms the strong progress being made by the IFMIF/EVEDA Project team.

A decisive step towards record light hadron beam performance and IFMIF-DONES validation

Europe and Japan have brought LIPAc to its full accelerator configuration in Rokkasho, Japan.
This milestone marks a decisive step for the IFMIF/EVEDA project and the future of fusion materials testing. With all major subsystems now installed, the 36-meters accelerator is ready to enter its next commissioning phase.

At its core, the SRF section aims at accelerating particles up to 9 MeV at 125 mA in continuous-wave operation. This highly demanding regime is essential to reduce the main technical risks for future fusion neutron source facilities such as IFMIF-DONES and A-FNS.

With assembly completed, the teams will now proceed with progressive commissioning, including RF conditioning, cryogenic operation and integrated tests. Warm conditioning is planned to start in June 2026 and beam operations are planned to start by March 2027, first with protons and then with deuterons. LIPAc now enters a decisive phase to turn years of European-Japanese collaboration into demonstrated accelerator capability.

The injector CW campaign was interrupted during a few weeks to fix two technical issues which appeared in a row just after resuming this activity at the beginning of 2023. For the first one, a fuse and few transistors were found damaged in the power supply of the second source coil. Procurement of new components was relatively fast and allowed fixing the power supply in a timely manner. The second difficulty came immediately after resuming injector operations and was linked to the power supply of the magnetron. On-site investigations did not allow to determine the reason of this failure. The power supply was replaced by a spare one from same manufacturer with different remote control interfaces. Yet few adjustments were needed to accommodate a different communication protocol and physical interfaces. The control system group worked closely with the injector group to update the local control system. Tests were performed in manual and remote modes to confirm signal synchronization with timing system, interlocks and operability from injector OPI (Operator Interface). Eventually, the injector operations with deuteron beam resumed on 29 March with the 11mm PE (plasma electrode). While plasma conditioning is organized during nights, beam extractions is performed during evening shifts and reached 150 mA extracted current at 100% DC (duty cycle) in the last days. Emittance measurements are performed at 5% DC for different beam extraction conditions. The objective is to gather enough data to compare results with the ones of previous injector campaign in 2022 using same PE diameter.

The main reason preventing injector operations during the daytime is related to RFQ activities. Indeed, the assembly of the Oring couplers was performed in a cleanbooth mounted in the vault. After each assembly, the coupler was mounted on a local vacuum chamber next to the cleanbooth to perform vacuum leak test. Though the coupler assembly procedure was well detailed, the percentage of successful leak tests was rather low for the first assemblies. A number of adjustments were introduced in the assembly sequence in order to obtain vacuum tight assemblies. Once validated on the vacuum test bench, each Oring coupler was mounted on the RFQ. Special care was given to the cleanliness aspects with the use of a large cleanbooth installed on both sides of the RFQ and able to host 2 operators. A smaller cleanbooth was installed in the first one around the RFQ port on which was mounted the Oring coupler. After completing the installation of the 8 Oring couplers, vacuum was pulled in the RFQ for a global leak test. After tightening further few bolts, the RFQ vacuum leak test was validated. The RFQ was brought back to atmospheric pressure to allow the assembly of the coaxial lines, which should start just after removing all the scaffoldings used for coupler assembly and also after reconnection of water piping and cables on the couplers.

Meanwhile, the conditioning of the first pair of brazed couplers on RFQ RF chain 4A was terminated in March. It reached 96.3% duty cycle at 196 kW but with 130 kW of reflected power. While the first brazed coupler can be considered as fully conditioned, the second coupler was not exposed to full RF power and its conditioning should be completed later. The HPTB (High-Power Test Bench) was dismounted last month to allow activities on the MEBT SSPA and remounting of the coaxial lines in view of the LIPAc beam operations.

Another RF test bench was mounted on the RFQ RF chain 3B to condition the spare ceramic disks of the Oring couplers. A first ceramic disk was mounted and conditioned up to 150kW at 55% DC, but the test was put on hold as temperatures were reaching 86°C on the RF window flanges. A second ceramic disk was mounted for comparison and is under testing.

After their delivery and unpacking in Rokkasho BA site, the circulators 1A and 1B have been mounted on the RFQ RF module #1. Besides the heavy components and the limited space between RF modules and control cubicles, the detailed procedure prepared in advance allowed a smooth assembly operation. A water pressure test was performed after reconnection of water piping and get successful after fixing a few leaks. Measurements of RF characteristics for each circulator were performed successfully at different temperatures. The position of the circulators was adjusted during an alignment campaign with laser tracker. Before connecting the circulators to the RFQ with coaxial lines, a last RF power test will be performed by mounting a RF load at the output of each circulator.