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.

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.

Based on the results of the IFMIF/EVEDA project in the broader approach (BA) activities, the conceptual design of the Advanced Fusion Neutron Source (A-FNS) to obtain irradiation data of DEMO blanket materials is under consideration in Japan. This paper describes the progress of the A-FNS conceptual design, which consists of a 40 MeV, 125 mA deuteron beam, a liquid lithium target system, and a test and post-irradiation test facilities. the main objectives of the A-FNS are the acquisition of RAFM irradiation data up to 2035 and the tritium recovery test on the blanket. In addition, it is expected to be used for various neutron researches. The technical design activities of the A-FNS are focused on improvement of the lithium target design, review of impurity criteria, remote handling, and irradiation application plan.

The Linear IFMIF (International Fusion Materials Irradiation Facility) Prototype Accelerator (LIPAc) is aiming at demonstrating the low energy section of a 40 MeV/125 mA IFMIF deuteron accelerator up to 9 MeV with a full beam current in cw operation. For such a high-power beam, the LIPAc injector is required to produce a 100 keV D+ beam with 140 mA and match it for injection into the Radio Frequency Quadrupole (RFQ) accelerator. The injector is designed by CEA-Saclay based on the high intensity light ion source (SILHI). In 2019, the commissioning of the RFQ to demonstrate the D+ beam acceleration at a low duty cycle (0.1%) was conducted. A nominal beam current of 125 mA D+ beam was accelerated up to 5 MeV through the RFQ successfully. The LIPAc injector fully satisfied the requirements for RFQ beam commissioning at the pulse mode.

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.

The installation and commissioning of the LIPAc are ongoing under the Broader Approach agreement, which is the prototype accelerator of the IFMIF for proof of principle and design. The deuteron beam will be accelerated by the RFQ linac from 100 keV to 5 MeV during the commissioning phase-B and by the SRF linac up to 9 MeV during the phase-C. The commissioning phase-B+ will be implemented between phase-B and C to complete the engineering validation of the RFQ linac before installing the SRF linac. The lattice for the deuteron beam of 5 MeV and 125 mA at the commissioning phase-B+ was designed. INTRODUCTION The International Fusion Materials Irradiation Facility (IFMIF) aims to provide an accelerator-based, D-Li neutron source to produce high energy neutrons for DEMO reactor materials qualification. The Linear IFMIF Prototype Accelerator (LIPAc) is the prototype accelerator of the IFMIF for proof of principle and design. The installation and commissioning of the LIPAc are ongoing under the Broader Approach agreement, concluded between the European Atomic Energy Community (Euratom), whose implementing agency is F4E, and Japan [1, 2]. Figure 1: Accelerator components at (a) commissioning phase-B, (b) phase-B+, and (c) phase-C and D. At the LIPAc, the deuteron beam (D+) of 140 mA generated from the injector will be accelerated by the RFQ linac from 100 keV to 5 MeV. During the commissioning phase B, the D+ will be transported through the medium beam transport system (MEBT) and the beam diagnostic system (D-plate), and then it will be absorbed by the low power beam dump (LPBD) (see Fig.1(a)). It should be noted that, at the MEBT, there are 2 scrapers to remove the halo and 2 bunchers to match the longitudinal beam distribution to the SRF’s one (see Fig. 2). Figure 2: Schematic view of LIPAc at phase-B+. The commissioning phase-B+ will be implemented between phase-B and C. Its main goal is to validate the CW operation of the RFQ linac on the condition of the D+ with 125 mA and 5 MeV for 30 minutes before installing the SRF linac. The phase-B+ consists of substituting the SRF linac in the phase-C configuration for a new beam transport line, which is called the drift line (see Figs. 1(b) and (c)). After passing through the drift line and the high energy beam transport system (HEBT) merged with the D-plate, the D+ will be absorbed by a high power beam dump (HPBD). During the phase-C, the D+ will additionally be accelerated by the SRF linac up to 9 MeV. The CW operation is not foreseen in phase-C, and it is foreseen in the phase-D whose accelerator components is identical with those of the phase-C. In the new drift line at the Phase-B+, 4 quadrupole magnets, 2 steering magnets and 2 BPMs are assembled (Fig. 2). In order to meet the beam requirements for the phaseB+, the lattice design was performed. The beam requirements and results are presented in detail. REQUIREMENTS FOR PHASE-B+ The requirements for the phase-B+ are listed as follows: • The installation of the SRF linac is planned after the phase-B+, so that the installation and un-installation of the drift line must be simple. Therefore, it is planned that 4 quadrupole magnets are installed as the ____________________________________________ †shimosaki.yoshito@qst.go.jp 10th Int. Particle Accelerator Conf. IPAC2019, Melbourne, Australia JACoW Publishing ISBN: 978-3-95450-208-0 doi:10.18429/JACoW-IPAC2019-MOPTS051 MC4: Hadron Accelerators A08 Linear Accelerators MOPTS051 977 Co nt en tf ro m th is w or k m ay be us ed un de rt he te rm so ft he CC BY 3. 0 lic en ce (© 20 19 ). A ny di str ib ut io n of th is w or k m us tm ai nt ai n at tri bu tio n to th e au th or (s ), tit le of th e w or k, pu bl ish er ,a nd D O I

The Linear IFMIF (International Fusion Materials Irradiation Facility) Prototype Accelerator (LIPAc) injector consists of a 140 mA proton/deuteron source, its associated low energy beam transport line (LEBT) as well as ancillaries such as water cooling skid, vacuum groups, High Voltage Power Supplies (HVPS), etc. A specific element, the beam "Chopper", was included in the LEBT to generate short ((similar to)100 mu s) and sharp-edged beam pulses ((similar to)10 mu s) and allow the use of interceptive diagnostics in the high energy part of the LIPAc during commissioning phases of the Radio Frequency Quadrupole RFQ (5 MeV) and the Superconducting Radio Frequency SRF Linac (9 MeV). The chopper was designed to operate in pulsed mode with very sharp rise and fall times, meaning the chopper will be used to "cut" the long rise time of the source as well as the fall time of the beam pulse. The chopper thermal screen has not been designed to withstand very high beam power (i.e., beam length and duty cycle need to be monitored); in addition, the chopper HVPS needs to be monitored in real time to detect a possible trip and extract the beam before downstream devices are damaged. For these applications, standard PLC based interlocks are too slow; therefore, faster solutions are envisaged. The proposed solution for the required interlock system is based on COTS technology with XILINX FPGAs using RIO (Reconfigurable Input/Output) technology from National Instruments (CompactRIO platform). The paper discusses the implementation of the interlock system, the response times of the proposed architecture and the fitness of the technology. Additionally, the system can be integrated into the IFMIF control system using EPICS as a standalone solution.

The International Fusion Materials Irradiation Facility (IFMIF) is an accelerator-based D-Li neutron source, in which two 40-MeV Deuteron beams with a total current of 250 mA impact on a liquid Li stream flowing at 15 m/s (Li target). In the IFMIF/EVEDA project under the Broader Approach (BA) agreement, the Li target was continuously operated with the cold trap and satisfied the stability requirement throughout the continuous operation. The linear IFMIF prototype accelerator (LIPAc) is currently under development in Rokkasho, Japan, to demonstrate the 9 MeV/125 mA D-beam acceleration. Recently, the first proton beam was injected into the RFQ with more than 90 % transmission, followed by the first Deuteron beam accelerated at 5 MeV. The superconducting RF linac necessary for the 9-MeV D+ beam is nearing completion of the manufacturing phase and will be assembled in Rokkasho. Based on the results from the IFMIF/EVEDA project, a conceptual design of the Advanced Fusion Neutron Source (AFNS) for its construction in Rokkasho is underway to obtain material irradiation data necessary for a fusion DEMO reactor. The A-FNS is composed of an accelerator with a 40-MeV and 125-mA deuteron beam, a test facility including a liquid Li target system and a post irradiation examination facility, which is designed to be able of multipurpose utilizations for neutron application as well.

A key conception of the remote maintenance (RM) method is presented of the target assembly (TA) of Advanced Fusion Neutron Source (A-FNS), that is an accelerator-driven fusion neutron source utilizing the Li(d,xn) nuclear reactions. The RM method, newly proposed here, is aimed at (i) enhancing the modularity of the TA RM and (ii) keeping the compatibility with the materials irradiation tests, compared to the preceding TA RM design of International Fusion Material Irradiation Facility (IFMIF). A 3-dimensional kinematics simulation indicates that the large clearance of 52 mm between the TA and high flux test module (HFTM) brings the independent removal from and the installation in the test cell, regardless of the presence of the test modules in the test cell. A neutronics performance of the HFTM with the enlarged clearance is also studied. The gradient of the calculated neutron irradiation damage is found to be decreased and satisfies a users’ requirement of the irradiation environment when the clearance is enlarged from 2 to 52 mm. (The former value was the IFMIF engineering design value.) These simulation results suggest that the proposed TA RM method will enhance not only the modularity of the TA, but also will improve the materials irradiation test environment.

The alleviated limits of impurities of nitrogen and hydrogen isotopes in lithium are suggested to be 400wppm and 550appm, respectively for early realization of Advanced Fusion Neutron Source planned in Japan. The applicability of the suggestion is discussed by comparing to that of IFMIF. As the results, not less than 4-year buffer for R&D of nitrogen trap are brought in, which is thought as one of bottle neck. Additionally, the application of this suggestion would diminish the beryllium (a radioactive isotope will generate in A-FNS process) concentration in processing lithium, as well. On the other hand, it is indicated that there would be no fatal problems by application of the present suggestion.

The IFMIF (International Fusion Materials Irradiation Facility) Prototype Accelerator (LIPAc) has been developed in the Engineering Validation and Engineering Design Activity (EVEDA) phase. The LIPAc is designed to produce a deuteron CW beam with a current and an energy of 125 mA and 9 MeV. After the injector campaign, the LIPAc is entering the RFQ (Radio-Frequency Quadrupole) commissioning phase in which such subsystems as the RFQ, RF system and Beam Instrumentation systems have been attached. The LIPAc control system consists of local control systems (LCSs) and the central control system. The LCSs haven been developed by Europe and delivered with the subsystems; and the central control system, including personnel and machine protection, timing, archiving and alarming, has been developed by Japan. Japan and EU are jointly integrating them to control the whole accelerator in an organized manner. Fabrication of the control system is made on the EPICs platform to reduce the risk in integration. Some part of the protection systems has been implemented in FPGA to satisfy both the speed and sophisticated control. The basic idea and implementation of the control system will be presented.

Based on results from the IFMIF/EVEDA project in the Broader Approach (BA) activities, a conceptual design of the Advanced Fusion Neutron Source (A-FNS) in Rokkasho, Aomori aiming at obtaining material irradiation data for a fusion DEMO reactor is presented in this paper. The A-FNS is composed of an accelerator facility with a 40 MeV and 125 mA deuteron beam, a test facility including a liquid lithium target system and a post irradiation examination facility. The prime objective of A-FNS is the data acquisition of RAFM irradiation data by 2035 and the tritium recovery test on the blanket and durability test on the fusion diagnostic and control devices. A particular attention in the design is paid on an integration of the test facilities by adopting a newly designed for A-FNS. Furthermore, as a unique usage of A-FNS neutron, the multipurpose usage has been investigated. For the mission achievement, the A-FNS/CDA will continue until 2020 and then the EDA will be continuously implement between 2020 and 2024. After the EDA, the A-FNS facility is to start constructing from 2025 toward the neutron operation around 2030. As current activity for A-FNS conceptual design, the analyses and investigations for test module, Li target and loop, remote maintenance, neutron monitor and multipurpose usage has been progressed to solve the design issues.

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.

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.

The International Fusion Material Irradiation Facility (IFMIF) aims at qualifying and characterizing materials capable to withstand the intense neutron flux originated in the D-T reactions of future fusion reactors by a neutron flux with a broad peak at 14 MeV, capable to provide >20 dpaifpy on small specimens, also qualified in this engineering validation engineering design activity (EVEDA) phase. Its broad mandate has been successfully achieved, only pending the validation of its accelerator with its conventional facilities. The validation of the IFMIF's accelerators will be achieved in this on-going phase, until December 2019, with the operation of a deuteron accelerator at 125 mA CW mode and 9 MeV, which is presently under installation and commissioning in Rokkasho (Japan). The target availability of the IFMIF facility, 70%, is one of its main challenges because it demands an extraordinary individual availability of the sub-systems, such as the accelerator, with 87%. The linear IFMIF prototype accelerator (LIPAc) presents a broad spectrum of ancillary equipment to optimize its operational beam time. A description of the nuclear HVAC of IFMIF has already been reported (Pruneri et al., 2016) [1]. The present paper describes the design of the conventional systems of LIPAc, among which we address the electrical power supply, the heating, ventilation, and air conditioning (HVAC), the heat rejection system (HRS), the service water system (SWS), the service gas system (SGS), the cryoplant system (Cryo), and the fire protection system (FPS). (C) 2017 Elsevier B.V. All rights reserved.

IFMIF, the International Fusion Materials Irradiation Facility, is presently in its engineering validation and engineering design activities (EVEDA) phase under the Broader Approach Agreement. The engineering design activity (EDA) phase was successfully accomplished within the allocated time. The engineering validation activity (EVA) phase has focused on validating the Accelerator Facility (AF), the Target Facility and the Test Facility (TF) by constructing prototypes. The ELTL at JAEA, Oarai successfully demonstrated the long-term stability of a Li flow under the IFMIF’s nominal operational conditions keeping the specified free-surface fluctuations below  ±1 mm in a continuous manner for 25 d. A full-scale prototype of the high flux test module (HFTM) was successfully tested in the HELOKA loop (KIT, Karlsruhe), where it was demonstrated that the irradiation temperature can be set individually and kept uniform. LIPAc, designed and constructed in European labs under the coordination of F4E, presently under installation and commissioning in the Rokkasho Fusion Institute, aims at validating the concept of IFMIF accelerators with a D+ beam of 125 mA continuous wave (CW) and 9 MeV. The commissioning phases of the H+/D+ beams at 100 keV are progressing and should be concluded in 2017; in turn, the commissioning of the 5 MeV beam is due to start during 2017. The D+ beam through the superconducting cavities is expected to be achieved within the Broader Approach Agreement time frame with the superconducting cryomodule being assembled in Rokkasho. The realisation of a fusion-relevant neutron source is a necessary step for the successful development of fusion. The ongoing success of the IFMIF/EVEDA involves ruling out concerns about potential technical showstoppers which were raised in the past. Thus, a situation has emerged where soon steps towards constructing a Li(d,xn) fusion-relevant neutron source could be taken, which is also justified in the light of costs which are marginal to those of a fusion plant.

The necessity of a neutron source for fusion materials research was identified already in the 70s. Though neutrons induced degradation present similarities on a mechanistic approach, thresholds energies for crucial transmutations are typically above fission neutrons spectrum. The generation of He via 56Fe (n,α) 53Cr in future fusion reactors with around 12 appm/dpa will lead to swelling and structural materials embrittlement. Existing neutron sources, namely fission reactors or spallation sources lead to different degradation, attempts for extrapolation are unsuccessful given the absence of experimental observations in the operational ranges of a fusion reactor. Neutrons with a broad peak at 14MeV can be generated with Li(d,xn) reactions; the technological efforts that started with FMIT in the early 80s have finally matured with the success of IFMIF/EVEDA under the Broader Approach Agreement. The status today of five technological challenges, perceived in the past as most critical, are addressed. These are: 1. the feasibility of IFMIF accelerators, 2. the long term stability of lithium flow at IFMIF nominal conditions, 3. the potential instabilities in the lithium screen induced by the 2×5 MW impacting deuteron beam, 4. the uniformity of temperature in the specimens during irradiation, and 5. the validity of data provided with small specimens. Other ideas for fusion material testing have been considered, but they possibly are either not technologically feasible if fixed targets are considered or would require the results of a Li(d,xn) facility to be reliably designed. In addition, today we know beyond reasonable doubt that the cost of IFMIF, consistently estimated throughout decades, is marginal compared with the cost of a fusion reactor. The less ambitious DEMO reactor performance being considered correlates with a lower need of fusion neutrons flux; thus IFMIF with its two accelerators is possibly not needed since with only one accelerator as the European DONES or the Japanese A-FNS propose, the present needs >10 dpa/fpy would be fulfilled. World fusion roadmaps stipulate a fusion relevant neutron source by the middle of next decade, the success of IFMIF/EVEDA phase is materializing this four decades old dream.

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.

Ion species ratio of high current positive hydrogen/deuterium ion beams extracted from an electron-cyclotron-resonance ion source for International Fusion Materials Irradiation Facility accelerator was measured by the Doppler shift Balmer-α line spectroscopy. The proton (H+) ratio at the middle of the low energy beam transport reached 80% at the hydrogen ion beam extraction of 100 keV/160 mA and the deuteron (D+) ratio reached 75% at the deuterium ion beam extraction of 100 keV/113 mA. It is found that the H+ ratio measured by the spectroscopy gives lower than that derived from the phase-space diagram measured by an Allison scanner type emittance monitor. The H+/D+ ratio estimated by the emittance monitor was more than 90% at those extraction currents.