In a fusion reactor, the plasma based on a deuterium-tritium reaction generates high energy neutron flux interacting with the materials of the plasma facing components. In order to study the irradiated behavior of these materials, the International Fusion Materials Irradiation Facility (IFMIF) was conceived to generate these fusion relevant neutrons through d-Li stripping source. IFMIF is presently in its Engineering Validation and Engineering Design Activities (EVEDA) phase under the Broader Approach agreement signed between EURATOM and Japanese Government in 2007. This agreement mandates the IFMIF/EVEDA project to validate the design of the different systems of IFMIF and to produce an integrated engineering design of IFMIF, together with the data necessary for future decisions on its construction and operation. While the Engineering Validation Activity (EVA) of the Lithium Target Facility and the Test Facility was completed by constructing prototypes, the EVA of the Accelerator Facility with the Linear IFMIF Prototype Accelerator (LIPAc) is still on-going at the Rokkasho Fusion Institute, Japan. This paper overviews the achievements in the previous phase ended on 31 March 2020 and the progress in the current phase to complete the commissioning of the LIPAc.

The L inear I nternational Fusion Materials Irradiation Facility P rototype Ac celerator (LIPAc) is under commissioning in Rokkasho Fusion Institute in Japan and aims to accelerate 125 mA D+ at 9 MeV in Continuous Wave mode for validating the IFMIF accelerator design. To ensure a fine characterization and tuning of the machine many beam diagnostics are installed spanning from injector to the beam dump. The beam operations in 1.0 ms pulsed D+ at 5 MeV were successfully completed with a low power beam dump in 2019. Despite the challenges posed by the pandemic, the crucial transition to a new LINAC configuration was also finalized to enable operation in 1.0 ms — CW D+ at 5 MeV with the high-power beam dump. The 1 st beam operation of the configuration was carried out in 2021. The experiences and challenges encountered during these beam campaigns are described in this paper.

The Broader Approach (BA) activities aim to complement the ITER project and to promote the early realization of fusion energy through research, development, and tests of technologies supporting the future demonstration fusion reactor (DEMO). These activities are implemented under the BA agreement, which was signed and ratified in 2007 between Euratom and the Government of Japan. In essence, the BA activities consist of three projects:a) The Satellite Tokamak Programme Project JT-60SA, the world's largest superconducting tokamak until ITER starts, aims to support the assembly, commissioning and preliminary operation of ITER, and carry out demonstration and optimisation of steady-state operation of advanced plasma configurations for DEMO;b) The International Fusion Energy Research Centre (IFERC), which comprises three different sub-projects: the DEMO Design Research and Development Coordination Centre to coordinate design and R&D on materials and components for DEMO, the Fusion Computer Simulation Centre for the simulations of fusion plasmas, the analysis of experimental data, modelling of ITER operation, and contribution to the design of DEMO, and the Remote Experimentation Centre to allow scientists to participate remotely in fusion experiments from its control room in Japan;c) The Engineering Validation and Engineering Design Activities for the International Fusion Materials Irradiation Facility (IFMIF/EVEDA) focused on the design and validation of key components needed for the future Fusion Neutron Source facilities to characterize materials envisioned for DEMO.After 13 years of fruitful collaboration, Euratom and Japan launched the second phase of the BA activities in 2020. It is focused on exploiting and enhancing the facilities that have already been built and on working more closely than ever with ITER as the latter advances towards the first plasma. This paper will present a synthesis of the achievements already obtained thanks to the three BA projects and will address the future developments planned in 2023 and beyond.

The Linear IFMIF Prototype Accelerator, LIPAc, is being commissioned aiming at validating the RFQ up to 5 MeV beam acceleration. Eventually, the nominal beam of 5 MeV-125 mA in 1 ms length and 1 Hz rate pulsed mode was achieved in 2019. The beam operation has been resumed since July 2023 after a long maintenance including recovery from unexpected problems in the RFQ-RF system. This new phase aims at the commissioning of the full configuration except SRF LINAC, which is replaced by a temporary beam transport line. Focusing on the RFQ behavior, it will be interesting to operate it at higher duty, especially for longer pulses. Furthermore, a beam simulation study suggested that the beam extracted from the RFQ includes considerable momentum halo when the vane voltage reduces by more than 5 %, with a slight decrease of the mean energy. It can be a potential source of a quench like the mismatched beam in the cryomodule. This could be studied by measuring the energy from the Time -of -Flight among multiple BPMs while monitoring beam loss around the dipole, where momentum halo should be lost. During the beam commissioning phase, we studied them by scanning the RFQ voltage.

LIPAc is the Linear IFMIF Prototype Accelerator developed within the framework of the IFMIF project under the Broader Approach (BA) agreement signed between EURATOM and the Japanese Government in 2007. The IFMIF accelerator aims to provide an accelerator-based D-Li neutron source to produce high intensity neutron fluxes with appropriate energy spectrum in order to characterize materials envisioned for future fusion reactors. Because the IFMIF accelerator has to reach unprecedented performances, the feasibility is being tested through the design, manufacturing, installation, commissioning and testing activities of a 1:1-scale prototype accelerator, namely LIPAc, from the injector to the first cryomodule together with the High Energy Beam Transport line and the High Power Beam Dump. After outstanding results obtained in 2019, the LIPAc project has entered 2020 in the preparation of the third commissioning stage, i.e., validation in continuous-wave mode of the complete accelerator up to 5 MeV with its final beam dump. The validation until the nominal energy of 9 MeV will be made after the completion of cryomodule assembly. After a brief overview of the goals already achieved in the framework of the IFMIF/EVEDA program, this paper will present a synthesis of the results that have been obtained so far with the LIPAc accelerator as well as the future developments planned beyond 2020.

The current status and the progress of research and development (R&D) activities for a Fusion DEMO reactor in the National Institutes for Quantum and Radiological Science and Technology (QST) Rokkasho Fusion Institute is reported. In order to advance the Japanese DEMO activity, not only Japanese domestic activity but also international collaborations of Broader Approach activity and ITER-related activities are conducted in the QST Rokkasho Fusion Institute. Activities for DEMO design and relevant R&D; design of a fusion neutron source and development of an accelerator, ITER Test Blanket System; tritium handling technology; and information technology infrastructures, including a supercomputer system and a remote experimentation system, are carried out for a Fusion DEMO reactor.

The International Fusion Materials Irradiation Facility (IFMIF) is a projected accelerator-based, D-Li neutron source for fusion reactor materials qualification. LIPAc (Linear IFMIF Prototype Accelerator) is an accelerator aiming to generate a 125 mA, 9 MeV continuous wave deuteron beam, which is currently being commissioned in Rokkasho (Japan) with the objective of validating the IFMIF accelerator design. In LIPAc, a 10 m long High Energy Beam Transport line (HEBT) will connect the exit of the superconducting linac to the beam dump (BD). The HEBT line must accommodate the diagnostics for beam characterization and open the beam at the end to allow its stopping at the BD. The line contains several magnets to control the beam shape and its trajectory, maintaining beam losses below 1 W m−1 along the beamline to limit activation of surrounding elements and allow hands-on maintenance. In this work, the LIPAc HEBT line project is described since its origins. A summary of the beam dynamics calculations and other studies (vacuum, radioprotection, assembly, alignment) that led to the conceptual design of the line is done. After that, the detailed design of the line is presented, justifying the main design decisions taken and finally, the manufacturing and procurement process and the acceptance tests performed are summarized.

During the EVEDA (engineering validation and engineering design activities) phase of the International Fusion Materials Irradiation Facility (IFMIF) project, a 125 mA/9 MeV linear prototype accelerator (LIPAc) has to be built, tested and operated in Rokkasho-mura (Japan). Involved in this project for several years, CEA-Saclay designed the injector of this accelerator which is composed of an electron cyclotron resonance ion source, delivering a 140 mA deuteron beam at 100 keV, and a low energy beam transport (LEBT) line to match the beam for the injection into the radio-frequency quadrupole. In this paper, the components of the LIPAc injector are described. The commissioning of the ion source and LEBT with beam started in November 2014. The different phases of the commissioning are explained and some noticeable experimental results obtained with a D+ beam at 100 keV are presented.

IFMIF, the International Fusion Materials Irradiation Facility [1], is an accelerator-based neutron source that will use Li(d,xn) reactions to generate a flux of neutrons with a broad peak at 14 MeV, equivalent to the conditions of the Deuterium-Tritium reactions in a fusion power plant. IFMIF is conceived for fusion materials testing. The IFMIF prototype linear accelerator (LIPAc) is jointly developed by Europe and Japan within the IFMIF EVEDA project: it is composed of an ion source, a LEBT, a RFQ, a MEBT and a SC linac, with a final energy of 9 MeV. The 4-vane Radio Frequency Quadrupole (RFQ), developed by INFN in Italy, will accelerate a 130 mA deuteron beam from 0.1 to 5 MeV in continuous wave, for a beam power of 650 kW. The 9.8 m long, 175 MHz cavity is composed of 18 x 0.54 m long modules, flanged together and aligned within 0.3 mm tolerance. The RFQ was completed, delivered and assembled at the Rokkasho site and is presently under extended RF tests. The second phase of beam commissioning (up to 2.5 MeV/u) was scheduled to start at the end of 2017. Several unexpected issues and incidents significantly delayed the original program, which is however proceeding step by step toward the full achievement of its goals.

The Radio Frequency Quadrupole (RFQ) linac and 1.6 MW RF power system of the Linear IFMIF Prototype Accelerator (LIPAc) facility in the International Fusion Energy Research Center (IFERC) in Rokkasho (Japan) has been installed and conditioned. During the assembly and tuning process, the RFQ cavity was protected with a temporary tent from the potential deterioration of performance caused by dust. The vacuum in the cavity was improved through the 100 °C baking process of the cavity. The high power test of the 175 MHz RF systems up to 200 kW in CW for each of the eight RF chains was performed for checking its stable output reproducibility in Japan, before connecting 9–3/16 inch coaxial transmission lines from the RF chains to the RF input couplers of the cavity. It was confirmed that the eight RF chains provided the balanced RF power to the single RFQ cavity in-phase using a feedback loop and a synchronization system. The peak power in the cavity achieved 150 kW in the pulsed mode, which corresponds approximately to the required electric field to accelerate proton beam. Such RF conditioning process is ongoing to achieve 600 kW approximately required for deuteron beam commissioning planned in 2018.

Significant progress was obtained on the installation and commissioning of the Linear IFMIF Prototype Accelerator (LIPAc). On the injector experiment, the emittance of 0.2 πmm·mrad has been demonstrated, which is well smaller than that of required value (0.3 πmm·mrad). Eight sets of RF modules (175 MHz, 200 kW for each) were connected to the RFQ with 8 coaxial waveguides, and RF conditioning has been started. With a simultaneous power injection from 8 RF modules into the RFQ and careful conditioning, a required RF filed for the 5 MeV D+ beam acceleration was obtained at short pulse. The pulse extension is underway toward the CW operation. The first H+ beam acceleration will be started in June 2018. After the H+ beam commissioning, D+ beam acceleration will be implemented aiming at 5 MeV 125 mA, 0.1% duty. In parallel, the preparation of SRF (superconducting Radio-Frequency linac), which accelerates the D+ beam up to 9 MeV, has proceeded.

Significant progress was obtained on the installation and commissioning of the Linear IFMIF Prototype Accelerator (LIPAc). Eight RF chains (175MHz, 200kW for each) were connected to the RFQ with 8 coaxial waveguides, and RF conditioning has been started. With a simultaneous power injection from 8 RF chains into the RFQ and careful conditioning, a required RF filed for the 5MeV deuteron beam acceleration was obtained at 20 us pulse. The pulse extension is underway toward the CW operation. The first proton beam acceleration of 2.5MeV in RFQ has been successfully conducted in June 2018.

The LIPAc (Linear IFMIF Prototype Accelerator) is a 9MeV – 125 mA CW deuteron accelerator [1]. It is designed and manufactured in most parts in Europe and is being installed in Japan. Among its main components, the MEBT (Medium Energy Beam Transport line) [2] will shape the 5 MeV beam before its injection into the SRF Linac that will accelerate it up to its end energy. This paper addresses the engineering issues associated with the integration of the MEBT supplied by CIEMAT and SRF Linac supplied by CEA and CIEMAT at the LIPAc facility. It considers the seismic analysis of the beamline components and the tests and alignment activities performed in Europe prior to shipping the components to Rokkasho. MOTIVATIONS The LIPAc project is a collaboration between European and Japanese contributors. The Japanese contributors are mainly responsible for the design, manufacture and installation of the building and conventional facilities, while the European contributors supply most of the accelerator components and several other related equipment. This sharing implies a number of constraints that have to be taken into account for the design and assembly of the machine. Since the LIPAc will be installed in Japan, seismic analyses are necessary to ensure the integrity of the accelerator in case of earthquake. Since the machine is being manufactured in Europe, it is highly desirable to assemble and test most of the equipment before shipment to Japan for two main reasons. The first is to maximise the reaction time to resolve technical issue close to the manufacturing site. The second is to avoid delaying the schedule on LIPAc site operations where many other concurrent activities related to installation and commissioning of other equipment are performed [3]. A balance has to be found with the constraints linked to the shipment. The vibrations and accelerations encountered during a sea trip from Europe to Japan are indeed significant. If the equipment cannot sustain then another option is to use air transportation. Nonetheless, if these constraints are still too high for airplane transportation or if the cost is not acceptable, the solution is to ship the components separately and realize the assembly in Japan. Another important constraint is the alignment of the equipment that depends not only on the accuracy of the machining, but also on the tools and methods used during assembly and installation. If possible, it is always better to carry out an alignment campaign during assembly of the equipment and before shipment to Japan. The installation inside the LIPAc building can then be carried out more rapidly using some of the external frame CCR’s (Corner Cube Reflector) and re-checking the rest. MEBT Seismic Analysis An RS (response spectrum) analysis was performed to check the behaviour of the MEBT in case of a seismic event. A simplified model prepared from the 3D CAD mock-up was introduced to the Ansys v14.5 – workbench environment. The first six calculated natural modes from the modal analysis fall below 20 Hz, three of them are located in the maximum acceleration range (2-10 Hz) of the excitation spectrum. These modes contribute in great part to the maximum displacements observed in the RS analysis results at the top of the valves linked to the turbo pumps. Figure 1: MEBT deformation from RS analysis and turbo pump design change. As a result of the analysis, the supports were redesigned fixing the turbo pumps rigidly instead of using springs, see Figure 1. The RS analysis did not reveal more points that could be a problem for the MEBT. Assembly Test of ACCT Due to the reduced space at the interface between the RFQ (Radio Frequency Quadrupole) and the MEBT where the ACCT (AC Current Transformer) is located, it was decided to perform an assembly test of the ACCT Proceedings of IPAC2016, Busan, Korea WEPMR045 07 Accelerator Technology T33 Subsystems, Technology and Components, Other ISBN 978-3-95450-147-2 2377 C op yr ig ht © 20 16 C C -B Y3. 0 an d by th e re sp ec tiv e au th or s mounting, see Fig. 2. This operation requires dismounting the upper half of the first MEBT magnet in order to access to the ACCT screws. The difficulty is that these screws, that are accessible only by inserting a tool through the ACCT, have to be tightened alternatively by a quarter turn while the ACCT is displaced progressively. This is due to the presence of threaded holes on both side of the assembly, the ones on RFQ side having a chucking function whereas the ones on ACCT side are present to prevent the screws from falling into the ACCT. A first test showed that it was not possible to install the ACCT without the use of special tooling. A dedicated temporary support for the ACCT was designed, manufactured and used during a second assembly test. Notwithstanding the remaining poor accessibility, the test was successful and validated the assembly sequence. Figure 2: Assembly test of the ACCT. Alignment Campaign Since the MEBT tolerates sea shipment, all the main components (five quadrupoles, two scrapers, two bunchers, the beamline with four Beam Position Monitors and three turbo pumps) were assembled on the MEBT frame. An alignment survey was performed on all the MEBT components except of the second buncher, see Figure 3. The assembly table of the MEBT incorporates specific features defining the assembly coordinate frame. These features have been surveyed in the first step of the assembly and a best fit process has been launched to find the best match between the coordinate of the surveyed features and the nominal coordinates as defined in the reference CAD model. This process implicitly guarantees the best coincidence between the CAD coordinate frame and the assembly bench. The second phase of the assembly consisted in the characterization of the components to be installed. In this phase, each part of the MEBT has been measured and a proper set of offset distances has been defined to take into account the differences between the mechanical and magnetic axis of each part. On the basis of these preliminary activities the proper assembly of the MEBT started. Two Hexagon Laser Trackers have been used simultaneously to drive the operators to lock the part under installation in its final position. Each tracker was put on continuous measuring mode such as to produce in real time a simplified window showing the difference between measured and target points. The procedure proved to be very useful and time saving. Alignment was considered satisfactory only when the difference between target point coordinates and measured point coordinates was less than the global uncertainty of the measuring process. For the adopted process and layout, this uncertainty was not higher than 20 microns with a confidence level of 95%. The last phase of the assembly was the full survey of the fiducial supports of the MEBT. More than 80 fiducial nests have been surveyed many times realizing a database of more than 500 measurements. These coordinates will be used to assess dilations due to transportation to Rokkasho and, if necessary, to re-align the components after the delivery. Figure 3: Two laser trackers and watch windows during MEBT alignment campaign. SRF LINAC Seismic Analysis Similarly to the MEBT, RS analyses were performed for the SRF Linac to examine its behaviour during a seismic event. The cold mass includes a frame supporting the cavities, solenoids, couplers and He phase separator, and hangs from the top of the vacuum vessel by ten vertical Ti alloy rods and four horizontal ones in lateral direction. The first analysis revealed a potential problem at the interface between the cold mass and its support. The analysis results show that the cold mass would move nearly 10 mm longitudinally, which could damage its supporting structures. The problem was solved by adding two locking systems in the middle of the cold mass frame, thereby reducing the longitudinal displacement. Figure 4: SRF Linac design optimisation following seismic analyses. A second analysis highlighted a further swinging motion of the cavities and couplers (again nearly 10 mm in WEPMR045 Proceedings of IPAC2016, Busan, Korea ISBN 978-3-95450-147-2 2378 C op yr ig ht © 20 16 C C -B Y3. 0 an d by th e re sp ec tiv e au th or s 07 Accelerator Technology T33 Subsystems, Technology and Components, Other the longitudinal direction), and also on the He phase separator (around 2 mm). The central beam located in the middle of the cold mass frame, and to which all the cavities/solenoids are fixed via invar rods, was too flexible (7 mm of the 10 mm deformation mentioned previously). In addition, the stresses observed in the invar rods were above the yield limit of this material. Four modifications were applied to the design in order to improve the SRF Linac seismic behaviour, see Figure 4. The central beam was reinforced by changing its geometry. The invar rod diameter was increased from 8 to 12 mm and its fixing system to the central beam modified. Dampers were fixed to the base of the vacuum vessel to limit the displacement of the couplers and as a result the cavities and solenoids. A longitudinal bar linking all He phase separator supports was added. A third RS analysis showed that the implemented changes were sufficient to reduce the displacements of all the components (see Figure 5) and validate the design from a seismic perspective. Figure 5: SRF Linac deformation after design optimization. Assembly and Shipment The assembly of the SRF Linac beam line (cavities, solenoids, couplers) was initially planned in the premises of CEA at Saclay prior to shipment to Rokkasho [4]. A risk analysis was performed to assess the viability of this solution. As a result the decision was taken to carry out the assembly task in Rokkasho under the full responsibility of F4E (Fusion for Energy). A first reason was linked to the weakness of the ceramic coupler windows. These fragile components support the RF antennas located i

The objective of linear IFMIF prototype accelerator is to demonstrate 125 mA/CW deuterium ion beam acceleration up to 9 MeV. The injector has been developed in CEA Saclay and already demonstrated 140 mA/100 keV deuterium beam [R. Gobin et al., Rev. Sci. Instrum. 85, 02A918 (2014)]. The injector was disassembled and delivered to the International Fusion Energy Research Center in Rokkasho, Japan. After reassembling the injector, commissioning has started in 2014. Up to now, 100 keV/120 mA/CW hydrogen and 100 keV/90 mA/CW deuterium ion beams have been produced stably from a 10 mm diameter extraction aperture with a low beam emittance of 0.21 π mm mrad (rms, normalized). Neutron production by D-D reaction up to 2.4 × 10(9) n/s has been observed in the deuterium operation.

The linear IFMIF prototype accelerator (LIPAc) has been launched within the framework of the Broader Approach Agreement with the objective to validate the low energy part (9MeV) for the IFMIF linacs (40MeV, 125mA of D+ beam in continuous wave). Starting in mid-2007, the project is managed by the two Home Teams (JA-HT and EU-HT) and headed by the Project Team at the Broader Approach site in Rokkasho with the aim to complete the validation activity with the installation and commissioning of the whole LIPAc by June 2017. Following a short description and current status of each accelerator component, this paper describes the integration activities such as the 3D mockup integration and the Interface Management System (IMS) tools developed for use at the Integrated Project Team level. In preparation of the first equipment delivery in Japan at the beginning of 2013, implementation and installation activities of the various components are described, in particular assembly procedures associated with each subsystem.