IFMIF, the European–Japanese efforts under the Broader Approach agreement towards a Li(d,xn) neutron source: Current status and future options

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 14 MeV 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

Commissioning Plan of the IFMIF-DONES Accelerator

IFMIF-DONES (International Fusion Materials Irradiation Facility- DEMO-Oriented Neutron Early Source) - a powerful neutron irradiation facility for studies and certification of materials to be used in fusion reactors - is planned as part of the European roadmap to fusion electricity. Its main goal will be to characterize and to qualify materials under irradiation in a neutron field similar to the one faced in a fusion reactor. The intense neutron source is produced by impinging deuterons, from high-power linear deuteron accelerator, on a liquid lithium curtain. The facility has accomplished the preliminary design phase and is currently in its detailed design phase. At the present stage, it is important to have a clear understanding of how the commissioning of the facility will be performed, especially the commissioning of a 5 MW CW deuteron beam, together with the lithium curtain and the beam optimization for the neutron irradiation. In this contribution, the present plans for the hardware and beam commissioning of the accelerator will be given, focusing on the most critical aspects of the tiered approach and on the integration of the procedure with the lithium and tests systems

Étude de l'injection axiale d'un faisceau d'ions lourds dans un cyclotron compact

The aim of the OAE and OAI projects developed at GANIL is respectively to increase the ''medium'' heavy ion energies to get 45 MeV/A beams up to Xenon, and to increase the beam intensities. This study deals with the injection stage of the second of these operations. In this new design, the ECR source potential is 100 kV to avoid losses due to space charge. The inflector used for the injection in the cyclotron NC01 is a spiral type with two parameters. The equations of motion are straighforward to obtain and numerical simulation programs have been developed. It is then possible to compute the transfer matrix of this inflector and to study the behavior of the beam inside it. It is necessary to introduce an electrostatic quadrupole after the inflector exit to realize a good matching to the cyclotron with the condition of always staying inside the inflector acceptance. For these matching conditions, the inflector transmission is increased if one introduces a rotation of the inflector exit face. It is then possible to transfer beams with the required emittances and intensities in the OAI project. The knowledge of the inflector characteristics makes it possible to design an axial injection line to obtain a matched beamLe but des opérations OAE et OAI développées au GANIL est respectivement d'augmenter l’énergie des ions lourds de façon a délivrer des faisceaux de 45 MeV/A jusqu'au Xenon et d'en améliorer les intensités. Le travail retrace ici porte sur l’étage injecteur de la seconde de ces opérations. Dans cette configuration, une source ECR est portée a un potentiel de 100 kV afin d’éviter les pertes dues a la charge d'espace. L'inflecteur retenu pour réaliser l'injection dans le cyclotron NC01 est de type spiral a deux paramètres. Devant la difficulté de déterminer analytiquement les équations du mouvement, des programmes de simulation numérique ont été développés. Ces derniers permettent de calculer la matrice de transfert de cet inflecteur et d’étudier le comportement du faisceau a sa traversée. L'introduction d'un quadrupôle électrostatique en aval de l'inflecteur est nécessaire pour réaliser une bonne adaptation dans le cyclotron tout en restant dans l'acceptance de l'inflecteur. Pour les conditions d'adaptation retenues, la transmission de l'inflecteur est améliorée par l'introduction d'une rotation de sa face de sortie. Il est alors possible d'y transférer des faisceaux dont les émittances et les intensités sont celles envisagées dans le projet OAI. Connaissant les caractéristiques de l'inflecteur, la structure de la ligne d'injection axiale a pu être determinée afin de fournir un faisceau adapt

Cryomodule Development for the Materials Irradiation Facility: From IFMIF-EVEDA to IFMIF-DONES

International audienceFor several years, CEA has been involved in the development of superconducting linac for fusion related project, with the goal to develop an high flux neutrons source to test and qualify specific materials to be used in fusion power plants. In the framework of the ITER Broder Approch, a prototype cryomodule is under construction in Japan for the IFMIF/EVEDA phase(Engineering Validation and Engineering Design Activities) and the construction of the Accelerator Prototype (LIPAc) at Rokkasho, fully representative of the IFMIF low energy (9 MeV) accelerator (125 mA of D⁺beam in continuous wave). Meanwhile, the design studies of a plant called DONES (Demo Oriented NEutron Source, derived from IFMIF) started, with a superconducting linac made of 5 cryomodules. These one are based on the same principles as the one developed for IFMIF/EVEDA, but taking into account the lessons learnt from the prototype. This paper will present the similarities but also the differences between the cryomodules for IFMIF/EVEDA and DONES

Beam Dynamics Errors Studies for the IFMIF-DONES SRF-LINAC

International audienceThe goal of the IFMIF-DONES (International Fusion Materials Irradiation Facility-DEMO Oriented Neutron Source) project is to build an irradiation facility that will provide a sufficient neutron flux to study and characterize structure materials foreseen for future fusion power plant. In order to accelerate the required 125mA/40 MeV continuous deuteron beam from 5 MeV to 40 MeV, a superconducting radio-frequency (SRF) linac, housed in five cryomodules, is proposed. The design is based on two beta families (β=0.11 and β=0.17) of half-wave resonators (HWR) at 175MHz. The transverse focusing is achieved using one solenoid coil per focusing period. This paper presents the extensive multiparticle beam dynamics simulations that have been performed to adapt the beam along the SRF-linac in such a high space charge regime. As one of the constraints of the IFMIF linac is a low level of beam losses, specific optimizations have been done to minimize the beam occupancy in the line (halo). A Monte Carlo error analysis has also been carried out to study the effects of misalignments or field imperfections (static errors) and also vibrations or power supplies ripple (dynamic errors). The results of these errors studies are presented and discussed

Beam Dynamics Studies For the IFMIF-DONES SRF-Linac

International audienceThe DONES (DEMO oriented neutron source) project is aimed at constructing a DEMO of IFMIF to provide sufficient material damage [1]. In the SRF-Linac of this project, losses can cause harmful material activation and must be maintained much less than 1W/m. It's a challenge to keep losses at such a low level with high beam power and high space charge. This paper presents two designs of the DONES SRF-Linac, one with 4 cryomodules and another with 5 cryomodules. The design details to reduce the losses and the multi-particle simulation results will be shown. The errors studies for these results will also be discussed

Analysis of the Results of the Tests of IFMIF Accelerating Units

International audienceThe prototype IFMIF-EVEDA cryomodule encloses eight superconducting 175 MHz β=0.09 Half-Wave Resonators (HWR). They are designed together with the power coupler to accelerate a high intensity deuteron beam (125 mA) from to 5 to 9 MeV. Two cavity packages, complete with tuning system and power couplers, have been tested in a dedicated horizontal test cryostat - SaTHoRI (Satellite de Tests HOrizontal des Résonateurs IFMIF). The successful operational equivalent tests and tuning of the SRF accelerating units is reported