Abstract The Linear IFMIF (International Fusion Materials Irradiation Facility) Prototype Accelerator (LIPAc) is a key facility of the IFMIF/EVEDA project under the Broader Approach agreement, aiming to demonstrate the feasibility of high-current continuous-wave (CW) deuteron acceleration for fusion materials research. The LIPAc injector is designed to deliver a 140-mA deuteron beam at 100 keV to the RFQ while maintaining low emittance (≤0.25 π·mm·mrad) and high stability. In late 2024, a 24-hour CW operation was achieved with a total extracted current of 150 mA and a normalized rms emittance of 0.18 π·mm·mrad, meeting the LIPAc requirements. In addition, the degradation of boron nitride (BN) disks used in the ECR ion source during long-term operation was investigated, confirming its correlation with cumulated time of plasma in the source and its impact on beam quality. This paper reports on the LIPAc injector performance during CW commissioning and efforts to extend component lifetime through the study of BN disk degradation.

The IFMIF-DONES facility provides a very high intensity flux of neutrons for research on materials of future fusion reactors and other complementary applications. The generation of those neutrons is driven by stripping reactions between energetic deuteron particles and a liquid lithium jet. The requirements on the deuteron beam are to deliver a 40 MeV beam with a constant current of 125 mA. All the systems involved in the generation, acceleration, transport and shaping of the deuteron beam are grouped in the so-called accelerator systems (AS). The design of this high-power driver has been ongoing for a long time, and many prototypes of the critical technologies have been tested. During the last decade, the design has been consolidated and evolved into an engineering design ready for construction. The overview of the main features of the design and the current status is presented in this article.

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 continuous-wave operation. For such a high-power beam, the LIPAc injector is required to produce a beam current of 140 mA and 100 keV D + beams. The injector commissioning to reach high beam current has been progressing at high duty cycle operation, then stable operation for many hours at a beam condition of 150 mA total extracted current. This result demonstrates that the LIPAc injector can meet the required performance for nominal 125 mA long pulse deuteron beam acceleration.

For the development of the International Fusion Materials Irradiation Facility (IFMIF) aiming at material tests for fusion power plants, the construction of the Linear IFMIF Prototype Accelerator (LIPAc) has been conducted at Rokkasho, Japan under the Broader Approach Agreement. The commissioning of LIPAc has been progressing significantly. The world most powerful RFQ successfully accelerated proton beam of 58 mA, and an important project milestone of the acceleration of deuteron beam to 5 MeV with the beam current of 125 mA in pulse mode was successfully achieved. The result proves the validity of the present RFQ design. The adjustment and tuning of the RF power system and the injector for enabling an operation at maximum performances played an important role in achieving this result. For the next step, the preparation of the high duty cycle operation of RFQ is underway. The installation of the HEBT (High Energy Beam Transport line) and the beam dump accepting 1 MW, CW beam, has been completed and a new beam transport line is under manufacturing. Also the assembly of the Superconducting RF (SRF) linac to accelerate the beam up to 9 MeV started in a clean room in Rokkasho.

The construction of the Linear IFMIF Prototype Accelerator (LIPAc) is in progress in order to demonstrate the feasibility of the low energy section of an IFMIF deuteron accelerator up to 9 MeV with a beam current of 125 mA in CW. The next milestone of the project is the so-called Phase-B beam commissioning, and one of the missions is to demonstrate the acceleration of the proton beam up to 2.5 MeV or the deuteron beam up to 5.0 MeV in pulsed mode with a low duty cycle of 0.1% through RFQ. Most of the components and subsystems necessary for Phase-B were delivered by 2016 under the responsibility of Fusion for Energy (F4E) as in-kind contributions of several European institutes, namely CEA (France), CIEMAT (Spain), INFN (Italy), and SCK-CEN (Belgium), and QST is in charge of the installation of the delivered equipment. The installation and check-out of the RFQ subsystem and the RF power system was completed by July 2017, and the RF conditioning of the RFQ cavity started. Also, the installation and the check-out of the important sub-systems for Phase-B, namely MEBT and beam diagnostics, have been completed.

The Facility for Antiproton and Ion Research (FAIR) presently built in Darmstadt, Germany, will be dedicated to physics of unstable nuclei and antiprotons. The antiproton program at FAIR needs for various experiments the delivery of 7x10 10 pbar/h beams. Consequently, the acceleration chain composed of a proton-Linac and two syn-chrotrons, SIS 18 and SIS 100 has to deliver 2x10 16 pro-tons [1]. To this purpose, a 75 mA/ 68 MeV proton-Linac (p-Linac) is under construction. Its injector is composed of an Electron Cyclotron Resonance (ECR) ion source, a Low Energy Beam Transport (LEBT) line, a 3 MeV Ra-dio-Frequency Quadrupole (RFQ) and a Drift Transport Line (DTL) using Cross-bar H-mode cavities (CH). The CEA/Saclay is in charge, in the framework of a French-German collaboration, of designing, constructing and commissioning the proton-Linac injector composed of both the ECR proton source and the LEBT with dedicated diagnostics [2]. The on-axis species repartition of the proton beam is measured with a Wien Filter (WF), and the 2D-emittance with an Allison Scanner (AS) [3]. The targeted specifications are a proton beam current of 100 mA for an energy of 95 keV at the entrance of the RFQ within an emittance of 0.3π mm.mrad (rms norm). We present in this paper the latest results obtained with the injector in view of

The goal of LIPAc (Linear IFMIF Prototype Accelerator) is to achieve a 125 mA, 9 MeV, CW (continuous wave, i.e. 100% duty cycle) deuteron beam with an average beam power of 1.125 MW. In the beam current measurement, it is considered that calorimetric measurement is advantageous for high current and CW operations since it is not subject to secondary electrons, etc. In calorimetric measurements, it is necessary to measure the temperature rise of the cooling water as accurately as possible. We applied this method to LIPAc proton beams at the Beam Stop unit. In order to check the reliability, we inserted a heater in the cooling loop as a heat source and obtained correlation between the applied and measured power, which was found to be 1.0. Moreover, using this heater, accuracy of this measurement with respect to the flow rate of the cooling water was investigated. Due to heat transfer and the fluctuations of water temperature, etc., there is a range of flow rates in which the measurement error can be minitnized with our calorimetric measurement system.

The IFMIF accelerator facility consists of 2 identical linacs, each accelerating a 125 mA CW deuteron beam up to the energy of 40 MeV. In order to reach these unprecedented performances, the Linear IFMIF Prototype Accelerator (LIPAc) is under installation and commissioning at the International Fusion Energy Research Centre (IFERC) in Rokkasho, Japan, in the framework of the IFMIF/EVEDA project, which is part of the Broader Approach (BA) agreement between Japan and EU. The accelerator is designed to validate components up to 125 mA CW deuteron beam at 9 MeV. The accelerator components of LIPAc have been designed and manufactured mainly by European Institutes. The injector and superconducting linac, RFQ, MEBT, Diagnostics Plate, HEBT and beam dump have been developed respectively by CEA-Saclay, INFN-Legnaro and CIEMAT-Madrid and were delivered to Rokkasho between 2013 and 2016. The commissioning of the injector with beam started in November 2014. This paper dealt with the experimental data obtained with the beam diagnostics of the injector. The electrical measurements of the beam intensity on the beam stopper were compared with calorimetric measurements. The beam profiles measured with a CCD camera and a custom image-intensified CID camera are also addressed. The analysis of beam emittance and ion species fractions from data obtained with an Allison scanner is described and the results of species fraction measurements are compared with those obtained by using a deported spectrometer. Finally, the analysis of beam space potential from data obtained with a 4-Grid analyser is presented.

Internal continuous discharge can rapidly damage high-current ion sources and their extraction systems composed of several electrodes at high voltage. To prevent this continuous discharge inside the extraction system, a rapid prototype using an Experimental Physics and Industrial Control System (EPICS) software system for data acquisition has been implemented. During commissioning of the 140 mA deuterium electron cyclotron resonance ion source of the Linear IFMIF Prototype Accelerator (LIPAc), discharges were often observed during plasma tuning of the ion source and beam optics tuning of the extraction system. If such continuous discharge can be avoided, discharge-related damage such as melting electrode edges and holes in the boron nitride disk in the ion source can be minimized and thus an efficient machine operation can be achieved. A veto signal is output to the machine protection system, which is then in charge of the RF power shutdown of the ion source for a pre-determined time. The average reaction time of this system has been measured and is about 10 ms from discharge detection to RF power shutdown of the ion source with a 50 Hz sampling frequency. This is hundreds of times slower than hardware-based implementation. However, it prevents almost all continuous discharges at the LIPAc ion source and extraction system, and is still much faster than an operator's reaction time.

Commissioning of the injector for the IFMIF (International Fusion Materials Irradiation Facility) Linear Prototype Accelerator (LIPAc) was started at International Fusion Energy Research Centre (IFERC) located in Rokkasho, Aomori in November 2014. This report describes some results obtained during this commissioning period since November 2014. The normalized rms emittance for H+ beam with the energy of 100 keV and the extraction current of 137 mA was 0.28  mm mrad. The proton ratio of 80 % with H+ beam energy of 100 keV and the extraction current of 160 mA was obtained at the middle of the LEBT consisting of two solenoids. The deuteron operation was also started in July 2015. The preliminary results of the deuteron operation are also shown in this report. 1. はじめに 核融合炉材料開発において、D-T 核融合反応で生 成される 14 MeV の中性子による厳しい放射線環境 下にさらされる炉材料に対して、その照射試験によ る性能実証が必要不可欠とされてきた。この認識の 下、国際核融合材料照射施設(IFMIF)は、重陽子 -リチウム(d-Li)核反応による加速器駆動型中性 子源として、最大 1018 n/m2s というこれまでにない 強力な中性子場を生成する施設であり、その技術開 発が進められている。IFMIF では、大電流(125 mA ×2 基)の重陽子(D+)ビームを線形加速器で 40 MeV まで加速し、液体リチウムターゲットに入射す ることで、D-T 核融合反応を模擬した連続スペクト ルの中性子場を発生する。 2007 年より日欧の国際事業協定の一つとして始 まった IFMIFの工学実証・工学設計活動(EVEDA) では、IFMIF の原型加速器(Linear IFMIF Prototype Accelerator; LIPAc)の設計・製作・試験を行うこと が含まれている。この原型加速器は青森県六ケ所村 の国際核融合エネルギー研究センター(IFERC)に て、段階的にビーム試験を行う予定で進められてい る。LIPAc 入射器は 2013 年より輸送、据付が進めら れ[1]、2014 年 11 月 4 日に陽子(H+)によるビーム試 験を開始した。H+ビームでの加速器のコミッショニ ングを進めた後、2015 年 7 月 7 日に D+ビーム生成に 成功し、7 月 15 日に施設検査の受検、7 月 17 日に施 設検査の合格証を受けた [2]。 本稿では、IFERC に設置された LIPAc 入射器の概 要及びビーム試験の結果について報告する。 2. LIPAc 入射器の概要 IFMIF 加速器及びその原型加速器である LIPAc の 構成や現状については、参考文献[3]及び[4]に記され ている。LIPAc の入射器には Table 1 に示した性能が

The International Fusion Materials Irradiation Facility (IFMIF) linear IFMIF prototype accelerator injector dedicated to high intensity deuteron beam production has been designed, built, and tested at CEA/Saclay between 2008 and 2012. After the completion of the acceptance tests at Saclay, the injector has been fully sent to Japan. The re-assembly of the injector has been performed between March and May 2014. Then after the check-out phase, the production of the first proton beam occurred in November 2014. Hydrogen and deuteron beam commissioning is now in progress after having proceeded with the final tests on the entire injector equipment including high power diagnostics. This article reports the different phases of the injector installation pointing out the safety and security needs, as well as the first beam production results in Japan and chopper tests. Detailed operation and commissioning results (with H+ and D+ 100 keV beams) are reported in a second article.

To prove the feasibility of the IFMIF accelerators concept, the EVEDA phase will commission in Japan the LIPAC accelerator, which will deliver a 125 mA/9 MeV CW deuteron beam. LEDA already managed 100 mA in CW at 6.7 MeV in 2000. The different subsystems of LIPAC have been designed and constructed mainly by European labs with the injector developed by CEA-Saclay. This injector must deliver a 140 mA/100 keV CW deuteron beam at 99% D⁺ ratio, which is produced by a 2.45 GHz ECR ion source. The low energy beam transport line is based on a dual solenoid focusing system to transport the beam and to match it into the RFQ. The normalized RMS target emittance at the RFQ entrance is targeted to be within 0.25π mm·mrad. This article describes the diagnostics installed in the LEBT to measure beam parameters such as intensity, profile, emittance, species fraction and degree of space charge compensation. The article also focuses on the algorithm developed to analyze emittance data of high background from an Allison scanner. Species fractions (D⁺, D2+, D3+) using mass separation technique were also calculated with the Allison scanner installed between the two solenoids in a first stage.

Optical Transition Radiation (OTR) is emitted when a charged particle crosses the interface between two media with different dielectric properties. It has become a standard tool for beam imaging and transverse beam size measurements. At the KEK Accelerator Test Facility 2 (ATF2), OTR is used at the beginning of the final focus system to measure micrometre beam size using the visibility of the OTR Point Spread Function (PSF). In order to study in detail the PSF and improve the resolution of the monitor, a novel simulation tool has been developed. Based on the physical optic propagation mode of ZEMAX, the propagation of the OTR electric field can be simulated very precisely up to the image plane, taking into account aberrations and diffraction. This contribution presents the comparison between Zemax simulations and measurements performed at ATF2.

The primary aim of the ATF2 research accelerator is to test a scaled version of the final focus optics planned for use in next-generation linear lepton colliders. ATF2 consists of a 1.3 GeV linac, damping ring providing low-emittance electron beams (<12pm in the vertical plane), extraction line and final focus optics. The design details of the final focus optics and implementation at ATF2 are presented elsewhere* . The ATF2 accelerator is currently being commissioned, with a staged approach to achieving the design IP spot size. It is expected that as we implement more demanding optics and reduce the vertical beta function at the IP, the tuning becomes more difficult and takes longer. We present here a description of the implementation of the overall tuning algorithm and describe operational experiences and performances

The high charge PHIN photo-injector was developed within the framework of the European CARE program to provide an alternative to the drive beam thermionic gun in the CTF3 (CLIC Test Facility) at CERN. In PHIN 1908 electron bunches are delivered with bunch spacing of 1.5 GHz and 2.33 nC charge per bunch. Furthermore the drive beam generated by CTF3 requires several fast 180 deg phase-shifts with respect to the 1.5 GHz bunch repetition frequency in order to allow the beam combination scheme developed at CTF3. A total of 8 subtrains, each 140 ns long and shifted in phase with respect to each other, have to be produced with very high phase and amplitude stability. A novel fiber modulator based phase-switching technique developed on the laser system provides this phase-shift between two consecutive pulses much faster and cleaner than the base line scheme, where a thermionic electron gun and sub-harmonic bunching are used. The paper describes the fiber-based switching system and the measurements verifying the scheme. The paper also discusses the latest 8nC charge production and cathode life-time studies on Cs2Te.

At the first stage of the ATF2 beam tuning, vertical beam size is usually bigger than 3um at the IP. Beam waist measurements using wire scanners and a laser wire are usually performed to check the initial matching of the beam through to the IP. These measurements are described in this paper for the optics currently used (?x=4cm and ?y=1mm). Software implemented in the control room to automate these measurements with integrated analysis is also described. Measurements showed that beta functions and emittances were within errors of measurements when no rematching and coupling corrections were done. However, it was observed that the waist in the horizontal (X) and vertical (Y) plane was abnormally shifted and simulations were performed to try to understand these shifts. They also showed that multiknobs are needed in the current optics to correct simultaneously ?x, ?y and the horizontal dispersion (Dx). Such multiknobs were found and their linearity and orthogonality were successfully checked using MAD optics code. The software for these multiknobs was implemented in the control room and waist scan measurements using the ?y knob were successfully performed.