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Construction of the JT-60SA tokamak was completed on schedule in March 2020. Manufacture and assembly of all the main tokamak components satisfied technical requirements, including dimensional accuracy and functional performances. Development of the plasma heating systems and diagnostics have also progressed, including the demonstration of the favourable electron cyclotron range of frequency (ECRF) transmission at multiple frequencies and the achievement of long sustainment of a high-energy intense negative ion beam. Development of all the tokamak operation control systems has been completed, together with an improved plasma equilibrium control scheme suitable for superconducting tokamaks including ITER. For preparation of the tokamak operation, plasma discharge scenarios have been established using this advanced equilibrium controller. Individual commissioning of the cryogenic system and the power supply system confirmed that these systems satisfy design requirements including operational schemes contributing directly to ITER, such as active control of heat load fluctuation of the cryoplant, which is essential for dynamic operation in superconducting tokamaks. The integrated commissioning (IC) is started by vacuum pumping of the vacuum vessel and cryostat, and then moved to cool-down of the tokamak and coil excitation tests. Transition to the super-conducting state was confirmed for all the TF, EF and CS coils. The TF coil current successfully reached 25.7 kA, which is the nominal operating current of the TF coil. For this nominal toroidal field of 2.25 T, ECRF was applied and an ECRF plasma was created. The IC was, however, suspended by an incident of over current of one of the superconducting equilibrium field coil and He leakage caused by insufficient voltage holding capability at a terminal joint of the coil. The unique importance of JT-60SA for H-mode and high-β steady-state plasma research has been confirmed using advanced integrated modellings. These experiences of assembly, IC and plasma operation of JT-60SA contribute to ITER risk mitigation and efficient implementation of ITER operation.

The present contribution is devoted to the neutral beam injectors (NBIs) for ITER heating and current-drive. First, updated information is provided about the development status of the entire NBI prototype (MITICA); starting in 2021, the first experiments will be dedicated to high-voltage holding tests in vacuum. Then the contribution describes the full-scale prototype of the NBI ion source (SPIDER) and the activities performed in the first two years of operation, devoted to investigating the operational regimes of the ion source and verifying the performances of the various plants in view of extensive beam operation. Some improvements have already been implemented; others are being prepared for the next shutdown. The characterisation of the SPIDER plasma is presented and the results of the first beam operations are reported.

In the ITER neutral beam (NB) system, deuterium negative ion beam with 1 MeV, 40 A for 3600 s is required for plasma heating and current drive. The NB Test Facility (NBTF) is now being constructed in Padova, Italy, to achieve such high requirement prior to the ITER operation. Japan procures DC 1 MV power supply (PS) components for the NBTF and the ITER NB. Since this PS consists of various kinds of component with 100 m long, manufacturing and factory test have been performed over five years, and shipping and installation have been proceeded in parallel step by step as presented in the last FEC [A]. The on-site assembling technique for such complicated 1MV PS components is one of challenges not only for the ITER NB but also typical electrical components. As recent progress in the last two years, completion of assembly and also high-voltage insulation test of DC 1 MV power supply components are reported.

In the ITER neutral beam (NB) system, deuterium negative ion beam with 1 MeV, 40 A for 3600 s is required for plasma heating and current drive. The NB Test Facility (NBTF) is now being constructed in Padova, Italy, to achieve such high requirement prior to the ITER operation. Japan procures DC 1 MV power supply (PS) components for the NBTF and the ITER NB. Since this PS consists of various kinds of component with 100 m long, manufacturing and factory test have been performed over five years, and shipping and installation have been proceeded in parallel step by step as presented in the last FEC [A]. The on-site assembling technique for such complicated 1MV PS components is one of challenges not only for the ITER NB but also typical electrical components. As recent progress in the last two years, completion of assembly and also high-voltage insulation test of DC 1 MV power supply components are reported.

First operation of SPIDER and integrated power tests in MITICA.

To reach fusion conditions and to control the plasma configuration in ITER, the next step in thermonuclear fusion research, two heating and current-drive neutral beam injectors (NBIs) will supply 17MW each, by accelerating negative hydrogen or deuterium ions to 1MeV. The requirements of ITER NBIs (40A negative H or D ions for 1 hour) have never been simultaneously attained. So in the dedicated Neutral Beam Test Facility (NBTF) at Consorzio RFX (Italy) the performances of the ITER NBI (divergence

This paper gives an overview of the progress of the Neutral Beam Test Facility realization, including the experimental status of SPIDER.

Toward the ITER neutral beam (NB) system operating at DC -1 MV, several insulating techniques with oil, gas (air, SF6) and in vacuum have been developed. For the NB Test Facility (NBTF) established in Padua (Italy), the DC 1 MV power supply (PS) components such as transformers, transmission line, HV Deck and HV bushing have been manufactured, installed and the on-site acceptance tests have started to ensure compliance with the ITER requirement in advance of the ITER. The 1 MV acceleration voltage to produce deuterium negative ion beams with 1 MeV, 40 A for 3600 sec is obtained with five-stage (200kV each) DC generator (transformer and rectifier) and transmitted to the beam source in a single SF6-gas insulated transmission line (pressurized tanks) with length of ~100 m. During the installation of the transmission line, increase of contact resistance at connection points of the inner conductor inside the transmission line were observed. For such a long component, the tanks cannot be closed just after connecting the conductor. Thus, exposure to the air for several months induced the increase of the contact resistance. To avoid an electric and thermal impact on high-current conductors, a recovery technique of the contact resistance without disconnection was investigated. Finally, most of PS component have been installed and the voltage holding test for each section of the PS system as the on-site acceptance test has started. In this paper, recent progress of voltage holding test of the ITER NBTF DC 1 MV high-voltage PS including European component is reported.

The requirements of ITER neutral beam injectors (1 MeV, 40 A negative deuterium ion current for 1 h) have never been simultaneously attained; therefore, a dedicated Neutral Beam Test Facility (NBTF) was set up at Consorzio RFX (Padova, Italy). The NBTF includes two experiments: SPIDER (Source for the Production of Ions of Deuterium Extracted from Rf plasma), the full-scale prototype of the source of ITER injectors, with a 100 keV accelerator, to investigate and optimize the properties of the ion source; and MITICA, the full-scale prototype of the entire injector, devoted to the issues related to the accelerator, including voltage holding at low gas pressure. The present paper gives an account of the status of the procurements, of the timeline, and of the voltage holding tests and experiments for MITICA. As for SPIDER, the first year of operation is described, regarding the solution of some issues connected with the radiofrequency power, the source operation, and the characterization of the first negative ion beam.

The ITER Heating Neutral Beam (HNB) injectors, one of the tools necessary both to achieve burning conditions and to control plasma instabilities, are characterized by such demanding parameters as to require the construction of a Neutral Beam Test Facility (NBTF) dedicated to their development and optimization. The NBTF was realized in Padua (Italy), with the direct contribution of the Italian government, through the Consorzio RFX as the host entity, IO, the in kind contributions of three Domestic Agencies (F4E, JADA, INDA) and the technical and scientific support of various European laboratories and universities. The NBTF hosts two experiments: SPIDER and MITICA. The former is devoted to the optimization of the HNB and DNB ion sources and to the achievement of the required source performances. MITICA is the full size prototype of the ITER HNB, with an ion source identical to the one used in SPIDER. This paper gives an overview of the progress of the NBTF realization with particular emphasis on issues discovered during this phase of activities and to the adopted solutions in order to minimize the impact on the schedule while maintaining the goals of the facilities. The realization of MITICA is well advanced; it is expected to enter into operation in 2023 due to the long procurement times of the in-vessel mechanical components. The power supply designed to operate at 1MV are in an advanced phase of realization; all the high voltage components have been installed and the complex insulation test phase has begun in 2018. The construction and installation of SPIDER plant systems was successfully completed with their integration into the facility. The mechanical components of the ion source were installed inside the vessel and connected to the plants. The integrated commissioning with control (CODAS), protection and safety systems ended positively and the first experimental phase began. Finally, the first results of the SPIDER experimentation and of the 1MV insulation tests on the MITICA high voltage components are presented.

The achievement of burning plasma in ITER will require at least 33 MW of additional heating transferred to the plasma core by means of two 16.5 MW - 1 MeV injectors (N-NBI - Negative ion based - Neutral Beam Injector) of H or D atoms, with an extracted negative ion current of 40 A (i.e. 40 MW of extracted beam). A third Injector is foreseen as a future upgrade, to increase the power delivery to the ITER plasma up to 50 MW The N-NBI record so far obtained belongs to the Injector of JT60-U, in which have been extracted 17.4 A of negative current, accelerated up to 0.41 MeV. It is evident that the performances required for the ITER N-NBI exceed by far the present capability: for this reason, the Neutral Beam Test Facility - NBTF is under construction at the Consorzio RFX - Padova (I) premises, aimed at realizing the full scale prototype of the ITER N-NBI. Among other fundamental achievements (e.g. extracted current uniformity, efficient ion neutralization, long pulse duration), the success of the experimentation of the NBTF requires the achievement of a stable and easily obtained 1 MV voltage holding while negative ions are extracted and accelerated. The electrostatic configuration of the ITER and NBTF N-NBIs is extremely complex. It includes 5 main electrodes at high potential: five accelerating grids and a negative ion source, operating respectively at -0.2, -0.4, -0.6, -0.8, -1 MV with respect to the containing vessel. All electrodes have large surface (up to 10 m2 for the ion source, which constitutes the cathode); gap lengths are in the order of 100 mm between accelerating grids and a minimum of 980 mm for the -1 MV-to-ground gap. In such a peculiar situation, the full voltage attainment and holding is a key issue, being affected by Total Voltage Effect (TVE), Area Effect, residual gas pressure and electrode surface conditioning. This contribution aims to give an overview of the R&D so far carried out, in the Fusion Research Laboratories in particular the QST (formerly JAEA) lab in Naka, Ibaraki (Japan) , in the IRFM - CEA lab in Cadarache (France) and of the Italian Consorzio RFX lab in Padova. After a discussion of the present state-of-the-art about the voltage holding in the NBI accelerators, a description of the near future plan to achieve reliable voltage holding in the ITER N-NBI is given. The experiments will be performed in the labs of QST, RFX and, in a second stage, at the NBTF Facility in Padova. Finally, an example of spin-off of these researches is also given.

To reach fusion conditions and control plasma configuration in ITER, the next step towards establishing nuclear fusion as viable energy source, suitable combination of additional heating and current drive systems is necessary. Among them, two Neutral Beam Injectors (NBI) will provide 33MW hydrogen/deuterium particles electrostatically accelerated to 1MeV; efficient gas-cell neutralization at such beam energy requires negative ions, obtained by caesium-catalysed surface conversion of hydrogen/deuterium atoms in the ion source. ITER NBI requirements have never been simultaneously attained; so a Neutral Beam Test Facility (NBTF) was set up at Consorzio RFX (Italy). Experiments will verify continuous NBI operation for one hour, under stringent requirements for beam divergence (

The loss of extracellular matrix macromolecules from the cartilage results in serious impairment of joint function. Metalloproteinases called 'aggrecanases' that cleave the Glu373-Ala374 bond of the aggrecan core protein play a key role in the early stages of cartilage destruction in rheumatoid arthritis and in osteoarthritis. Three members of the ADAMTS family of proteinases, ADAMTS-1, ADAMTS-4 and ADAMTS-5, have been identified as aggrecanases. Matrix metalloproteinases, which are also found in arthritic joints, cleave aggrecans, but at a distinct site from the aggrecanases (i.e. Asn341-Phe342). The present review discuss the enzymatic properties of the three known aggrecanases, the regulation of their activities, and their role in cartilage matrix breakdown during the development of arthritis in relation to the action of matrix metalloproteinases.

Protease-substrate interactions are governed by a variety of structural features. Although the substrate sequence specificities of numerous proteases have been established, "topological specificities," whereby proteases may be classified based on recognition of distinct three-dimensional structural motifs, have not. The aggrecanase members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family cleave a variety of proteins but do not seem to possess distinct sequence specificities. In the present study, the topological substrate specificity of ADAMTS-4 (aggrecanase-1) was examined using triple-helical or single-stranded poly(Pro) II helical peptides. Substrate topology modulated the affinity and sequence specificity of ADAMTS-4 with K(m) values indicating a preference for triple-helical structure. In turn, non-catalytic ADAMTS-4 domains were critical for hydrolysis of triple-helical and poly(Pro) II helical substrates. Comparison of ADAMTS-4 with MMP-1 (collagenase 1), MMP-13 (collagenase 3), trypsin, and thermolysin using triple-helical peptide (THP) and single-stranded peptide (SSP) substrates demonstrated that all five proteases possessed efficient "triple-helical peptidase" activity and fell into one of two categories: (k(cat)/K(m))(SSP) > (k(cat)/K(m))(THP) (thermolysin, trypsin, and MMP-13) or (k(cat)/K(m))(THP) > or = (k(cat)/K(m))(SSP) and (K(m))(SSP) > (K(m))(THP) (MMP-1 and ADAMTS-4). Overall these results suggest that topological specificity may be a guiding principle for protease behavior and can be utilized to design specific substrates and inhibitors. The triple-helical and single-stranded poly(Pro) II helical peptides represent the first synthetic substrates successfully designed for aggrecanases.

Aggrecanases have been characterized as proteinases that cleave the Glu373-Ala374 bond of the aggrecan core protein, and they are multidomain metalloproteinases belonging to the ADAMTS (adamalysin with thrombospondin type 1 motifs) family. The first aggrecanases discovered were ADAMTS-4 (aggrecanase 1) andADAMTS-5(aggrecanase 2). They contain a zinc catalytic domain followed by non-catalytic ancillary domains, including a disintegrin domain, a thrombospondin domain, a cysteine-rich domain, and a spacer domain. In the case of ADAMTS-5, a second thrombospondin domain follows the spacer domain. We previously reported that the non-catalytic domains of ADAMTS-4 influence both its extracellular matrix interaction and proteolytic abilities. Here we report the effects of these domains of ADAMTS-5 on the extracellular matrix interaction and proteolytic activities and compare them with those of ADAMTS-4. Although the spacer domain was critical for ADAMTS-4 localization in the matrix, the cysteine-rich domain influencedADAMTS- 5localization. Similar to previous reports of other ADAMTS family members, very little proteolytic activity was detected with theADAMTS-5catalytic domain alone. The sequential inclusion of each carboxyl-terminal domain enhanced its activity against aggrecan, carboxymethylated transferrin, fibromodulin, decorin, biglycan, and fibronectin. Both ADAMTS-4 and -5 had a broad optimal activity at pH 7.0-9.5. Aggrecanolytic activities were sensitive to the NaCl concentration, but activities on non-aggrecan substrates, e.g. carboxymethylated transferrin, were not affected. Although ADAMTS-4 and ADAMTS-5 had similar general proteolytic activities, the aggrecanase activity of ADAMTS-5 was at least 1,000-fold greater than that of ADAMTS-4 under physiological conditions. Our studies suggest that ADAMTS-5 is a major aggrecanase in cartilage metabolism and pathology.

In multi-beamlet negative ion accelerators for fusion applications, the required transverse magnetic field for the suppression of co-extracted electrons is generated by permanent magnets arranged in parallel arrays, embedded in the Extraction Grid. However, such configuration also produces an undesired "criss-cross" deflection of ion trajectories, which can downgrade the overall beam optics. This deflection is traditionally counterbalanced by electrostatic means, i.e. by introducing a small offset in the axis of the grid apertures. During the final design of MITICA, which is the prototype of the ITER Heating Neutral Beam Injector presently under construction in Padova [1], an innovative magnetic configuration called ADCM (Asymmetric Deflection Compensation Magnets) has been conceived [2] and adopted, offering several advantages in terms of operational flexibility compared to the traditional solution. In the framework of a research collaboration between RFX and QST, the new concept has been experimentally tested for the first time in 2016 by a joint RFX-QST team. A new ITER-like [3] Extraction Grid (designed and built at RFX) was mounted on the existing NITS device at the QST lab in Naka. For direct comparison, half of the Extraction Grid was provided with the new ADCM configuration, whereas the rest of the grid had standard magnets with no compensation. A target made of monoaxial carbon-carbon fibre composite and an infrared camera were used for accurate beam optics measurement. The results obtained have confirmed the effectiveness of the ADCM concept for the compensation of the criss-cross ion deflection. Some discrepancies in the scaling of ion deflection with respect to 3D simulations were also evidenced and investigated. The paper presents the main results obtained during the experimental campaign on NITS at QST, which lasted in total six weeks, together with a discussion of the first data analysis results.

The negative ion accelerators for the ITER neutral beam system has been designed by using the conventional beam codes for the positive ion accelerators because mechanism of meniscus formation of negative ions has not been clarified well. In this way, the operational window of the negative ion accelerators can be simply predicted, but the grid heat loading by peripheral beam (beam halo) could not be simulated. To understand the applicable range of the conventional codes to the negative ion accelerators, and then to understand the negative ion meniscus consequently, the benchmark tests between the conventional codes (BEAMORBT (BO) [1] and SLACCAD (SC)[2]) and the experiments have been performed under a joint experiment by RFX and QST on the Negative Ion Test Stand in Naka. Figure 1 shows one numerical results as an example with the grid configuration. The extraction voltage (Vext) is applied between the plasma grid (PG) and the extraction grid (EXG). The acceleration voltage (Vacc) is applied between EXG and the grounded grid (GG). Figure 2 shows the beam divergence angle as a function of Vext at Vacc of 20 kV. Vext with the minimum divergence angle are shown around 4.0 kV both in the numerical codes and the experimental result. The operational window can be predicted in the numerical codes. However, the absolute values of the divergence angle of the experiment was larger than those of the numerical result. One of reasons will be that the numerical code cannot represent the beam halo. Even in the numerical results, the divergence angle in the BO is slightly lower than that of the SC. To understand the meniscus effect to the beam divergence, the relationship between meniscus depth ?zmenis and beam divergence in the numerical results was compared as shown in Figure 3. The details are reported in the paper.

In understanding the mechanism of schizophrenia pathogenesis, a significant finding is that drug abuse of phencyclidine or its analog ketamine causes symptoms similar to schizophrenia. Such drug effects are triggered even by administration at post-adolescent stages. Both drugs are N-methyl-d-aspartate receptor (NMDAR) antagonists, leading to a major hypothesis that glutamate hypofunction underlies schizophrenia pathogenesis. The precise region that depends on NMDAR function, however, is unclear. Here, we developed a mouse strain in which NMDARs in the intralaminar thalamic nuclei (ILN) were selectively disrupted. The mutant mice exhibited various schizophrenia-like phenotypes, including deficits in working memory, long-term spatial memory, and attention, as well as impulsivity, impaired prepulse inhibition, hyperlocomotion and hyperarousal. The electroencephalography analysis revealed that the mutant mice had a significantly reduced power in a wide range of frequencies including the alpha, beta and gamma bands, both during wake and rapid eye movement (REM) sleep, and a modest decrease of gamma power during non-REM sleep. Notably, restoring NMDARs in the adult ILN rescued some of the behavioral abnormalities. These findings suggest that NMDAR dysfunction in the ILN contributes to the pathophysiology of schizophrenia-related disorders. Furthermore, the reversal of inherent schizophrenia-like phenotypes in the adult mutant mice supports that ILN is a potential target site for a therapeutic strategy.

The ITER Heating Neutral Beam Injector (HNB) is designed to deliver 16.5MW of additional power to the plasma with pulse duration of one hour. The beam acceleration is obtained by a multistage accelerator composed of five acceleration grids that are powered by the so-called Acceleration Grid Power Supply (AGPS). The AGPS feeds around 56MW at 1MV dc to the acceleration grids in quasi-steady state and is able to interrupt the power delivery in some tens of microseconds in case of grid breakdown. The operation of the AGPS will be controlled by a dedicated control system, the AGPS Local Control (AGPS-LC). The AGPS-LC will be in charge of coordinating the operation and interlocks of the AGPS, putting in place all necessary actions to protect the AGPS from internal and external faults and limit the amount of energy flowing from the power supply to the grids in case of breakdowns. The AGPS-LC will be interfaced to a central control devoted to the operation of the Neutral Beam Injector and to a central interlock system in charge of coordinating interlocks and protection functions of the overall plant. The coordination of actions and their time synchronization is of paramount importance to guarantee a reliable operation. The complexity of the system and the different operational scenarios require an in-depth analysis to identify the most suitable control and protection strategy during faults and breakdowns. Such analysis is based on the existing experience of the JT-60U negative ion HNB system and on dedicated simulations performed on a detailed model of the power supplies. This paper will present a strategy for the coordination of the AGPS integrated protection during faults and breakdowns. The operational scenario has been simulated by using software tools for circuit analysis and a proposal for the design of the AGPS-LC has been derived.

Udgivelsesdato: Apr.12

Heating neutral beam (HNB) injectors, necessary to achieve burning conditions and to control plasma instabilities in ITER, are characterized by such demanding parameters that a neutral beam test facility (NBTF) dedicated to their development and optimization is being realized in Padua (Italy) with direct contributions from the Italian government (through Consorzio RFX as the host entity) and the ITER international organization (with kind contributions from the ITER domestic agencies of Europe, Japan and India) and technical and scientific support from various European laboratories and universities. The NBTF hosts two experiments: SPIDER, devoted to ion source optimization for the required source performance, and MITICA, the full-size prototype of the ITER HNB, with an ion source identical to SPIDER. This paper gives an overview of the progress towards NBTF realization, with particular emphasis on issues discovered during this phase of activity and on solutions adopted to minimize the impact on the schedule and maintain the goals of the facilities. The realization of MITICA is well advanced; operation is expected to start in 2023 due to the long procurement time of the in-vessel mechanical components. The beam source power supplies, operating at 1 MV, are in an advanced phase of realization; all high-voltage components have been installed and the complex insulation test phase began in 2018. At the same time, construction and installation of SPIDER plant systems was successfully completed with their integration into the facility. The mechanical components of the SPIDER ion source were installed inside the vessel and connected to the plants. Integrated commissioning with the control, protection and safety systems ended positively and the first experimental phase has begun. The first results of the SPIDER experiment, with data from operational diagnostics, and the plans for the 1 MV insulation tests on the MITICA high-voltage components are presented.

ITER envisages the use of two heating neutral beam injectors plus an optional one as part of the auxiliary heating and current drive system, to reach the desired performances during its various phases of operation. The 16.5 MW expected neutral beam power per injector is several notches higher than worldwide existing facilities.In order to enable such development, a Neutral Beam Test Facility (NBTF) was established at Consorzio RFX, exploiting the synergy of two test beds, called SPIDER and MITICA. SPIDER is dedicated developing and char-acterizing large efficient negative ion sources at relevant parameters in ITER-like conditions: source and accel-erator located in the same vacuum where the beam propagates, immunity to electromagnetic interferences of multiple radio-frequency (RF) antennas, avoidance of RF-induced discharges on the outside of the source. Three years of experiments on SPIDER have addressed to the necessary design modifications to enable full perfor-mances. The source is presently under a long shut-down phase to incorporate learnings from the experimental campaign, in particular events/issues occurred during operation, which led to the identification of improvement opportunities/necessities (e.g. RF discharges, local burns, water leaks, other damages, configuration/design upgrades to maximize chances/margin to quest target parameters).Parallelly, developments on MITICA, the full-scale prototype of the ITER Neutral Beam Injector (NBI) featuring a 1 MV accelerator and ion neutralization, are underway including manufacturing of the beam source, accel-erator and the beam line components, while power supplies and auxiliary plants, already installed, are under final testing and commissioning.Integration, commissioning and tests of the 1 MV power supplies are essential for this first-of-kind system, unparalleled both in research and industry field. 1.2 MV dc insulating tests of high voltage components were successfully completed. The integrated test to confirm 1 MV output by combining invertor systems, DC gener-ators and transmission lines extracted errors/accidents in some components. To realize a concrete system for ITER, said events have been addressed and solutions for the repair and the improvement of the system were developed.Hence, NBTF is emerging as a necessary facility, due to the large gap with existing injectors, effectively dedicated to identify issues and find solutions to enable successful ITER NBI operations in a time bound fashion. The lessons learned during the implementation on NBTF and future perspectives are here discussed.

To reach fusion conditions and control the plasma configuration in ITER, the next step in tokamak fusion research, two neutral beam injectors (NBIs) will supply 16.5 MW each, by neutralizing accelerated negative hydrogen or deuterium ions. The requirements of ITER NBIs (40A/1 MeV D- ions for ≤1 h, 46A/870 keV H- ions for ≤1000 s) have never been simultaneously attained. So in the Neutral Beam Test Facility (NBTF, Consorzio RFX, Italy) the operation of the full-scale ITER NBI prototype (MITICA) will be tested and optimised up to full performances, focussing on accelerator (including voltage holding), beam optics, neutralisation, residual ion removal. The NBTF includes also the full-scale prototype of the ITER NBI source with 100 keV particle energy (SPIDER), for early investigation of: negative ion production and extraction, source uniformity, negative ion current density and beam optics. This paper will describe the main results of the first two years of SPIDER operation, devoted to characterizing plasma and beam parameters, including investigation of RF-plasma coupling efficiency and magnetic filter field effectiveness in reducing co-extracted electrons. SPIDER is progressing towards the first caesium injection, which aims at increasing the negative ion density. A major shutdown, planned for 2021, to solve the issues identified during the operation and to carry out programmed modifications, will be outlined. The installation of each MITICA power supply and auxiliary system is completed; in-vessel mechanical components are under procurement by Fusion for Energy (F4E). Integration, commissioning and test of the power supplies, procured by F4E and QST, as the Japanese Domestic Agency (JADA), will be presented. In particular, 1.0MV insulating tests were carried out step-by-step and successfully completed. In 2020 integrated tests of the power supplies on the accelerator dummy load started, including the assessment of their resilience to accelerator grid breakdowns using a short-circuit device located in vacuum. The aggressive programme, to validate the NBI design at NBTF and to meet ITER schedule (requiring NBIs in operation in 2032), will be outlined. Unfortunately, in 2020 the coronavirus disease infection affected the NBTF activities. A solution to proceed with integrated power tests despite the coronavirus is presented.

The ITER Neutral Beam Test Facility (NBTF), called PRIMA (Padova Research on ITER Megavolt Accelerator), is hosted in Padova, Italy and includes two experiments: MITICA, the full-scale prototype of the ITER heating neutral beam injector, and SPIDER, the full-size radio frequency negative-ions source. The NBTF realization and the exploitation of SPIDER and MITICA have been recognized as necessary to make the future operation of the ITER heating neutral beam injectors efficient and reliable, fundamental to the achievement of thermonuclear-relevant plasma parameters in ITER. This paper reports on design and R&D carried out to construct PRIMA, SPIDER and MITICA, and highlights the huge progress made in just a few years, from the signature of the agreement for the NBTF realization in 2011, up to now - when the buildings and relevant infrastructures have been completed, SPIDER is entering the integrated commissioning phase and the procurements of several MITICA components are at a well advanced stage

The realization of the ITER Neutral Beam Test Facility (NBTF) and the start the experimental phase are important tasks of the fusion roadmap, since the target requirements of injecting to the plasma a beam of Deuterium atoms with a power up to 16.5 MW, at 1MeV of energy and with a pulse length up to 3600s have never been reached together before. The ITER NBTF, called PRIMA (Padova Research on ITER Megavolt Accelerator), is hosted in Padova, Italy; it includes two experiments: MITICA, the full-scale prototype of the ITER injector and SPIDER, the full-size negative ion source. The realization promoted by the ITER organization is carried out with the contribution of the European Union, channeled through the Joint Undertaking for ITER (F4E), of the Consorzio RFX which hosts the Test Facility, the Japanese and the Indian ITER Domestic Agencies (JADA and INDA) and several European laboratories, such as IPP-Garching, KIT-Karlsruhe, CCFECulham, CEA-Cadarache. The early start of operation of PRIMA experiments is urgent because sufficient experimental time is necessary to face and solve the issues related to the achievement of the desired performance in time for the ITER operation, requiring NBI since the beginning. Substantial progresses have been recently achieved: the buildings construction, begun in October 2012, has been completed by the end of 2015 and the installation of some components has been started since the end of 2014. The SPIDER realization is well advanced: the installation phase is proceeding in good agreement with the general plan; it is expected to be almost completed by the end of 2016. In parallel, the commissioning of the SPIDER power supply (PS) and auxiliary plant systems is being proceeding. Tests at full power and remote control are planned, including also those addressed to reproduce the grid breakdowns and to test the relevant protections. The design of the MITICA injector components was completed in 2015their procurement is being made through a number of tenders, some of them already launched. The HV Power Supply system of the MITICA 1MV accelerator, provided by JADA, was delivered on site in December 2015. The challenging installation of these components, including the step-up transformers and the SF6 gas insulated transmission line, started soon after and will go on throughout 2016. The present phase, with the PRIMA buildings continuously filled with new components, with the installation activities progressing and with also the commissioning and testing phase starting represents a substantial step forward toward the main target. The paper will describe the main challenges the Project Team has dealt during this phase and the important feedback derived for the ITER HNB systems both from the technical and the organizational standpoints.

The ITER project requires additional heating by two neutral beam injectors, each accelerating to 1 MV a 40 A beam of negative deuterium ions, to deliver to the plasma a power of about 17 MW for one hour. As these requirements have never been experimentally met, it was recognized as necessary to setup a test facility, PRIMA (Padova Research on ITER Megavolt Accelerator), in Italy, including a full-size negative ion source, SPIDER, and a prototype of the whole ITER injector, MITICA, aiming to develop the heating injectors to be installed in ITER. This realization is made with the main contribution of the European Union, through the Joint Undertaking for ITER (F4E), the ITER Organization and Consorzio RFX which hosts the Test Facility. The Japanese and the Indian ITER Domestic Agencies (JADA and INDA) participate in the PRIMA enterprise; European laboratories, such as IPP-Garching, KIT-Karlsruhe, CCFE-Culham, CEA-Cadarache and others are also cooperating. Presently, the assembly of SPIDER is on-going and the MITICA design is being completed. The paper gives a general overview of the test facility and of the status of development of the MITICA and SPIDER main components at this important stage of the overall development; then it focuses on the latest and most critical issues, regarding both physics and technology, describing the identified solutions.

For a stationary two-dimensional random field evolving in time, we derive the intensity distributions of appropriately defined velocities of crossing contours. The results are based on a generalization of the Rice formula. The theory can be applied to practical problems where evolving random fields are considered to be adequate models. We study dynamical aspects of deep sea waves by applying the derived results to Gaussian fields modeling irregular sea surfaces. In doing so, we obtain distributions of velocities for the sea surface as well as for the envelope field based on this surface. Examples of wave and wave group velocities are computed numerically and illustrated graphically. 12 18 25 Sponsors: ISOPE Kyushu University Conference code: 62589

Aluminium patrol boats have been designed for operations under severe conditions. The ship hull must withstand high global and local stresses in rough sea conditions and the aluminium structural details must not fail due to fatigue. The speed of the ship and the hull shape may increase the probability of wave impacts and the hydroelastic structural behaviour with which the wave loads exite hull vibration in the lowest eigenfrequency, which considerably increases the number of load cycles. In predictions of wave loads and structural behaviour for design purposes, non-linear wave loads and hydroelastic structural behaviour must be taken into account. The use of traditional linear frequency domain analysis leads to severe underestimation of maximum hull girder stresses, stress ranges and also the number of load cycles. This has been confirmed by global stress measurements during sea-keeping trials. A numerical simulation procedure base on the non-linear strip theory has been developed for time-domain analysis of wave loads and structural response. The procedure takes into account, in an approximate way, non-linear wave loasd due to rarge ship motions. The structural analysis model includes the dynamic structural behaviour. The post-processing of the simulated rasults has been developed for application in structural design work. The calculated results include, for example, prediction of maximum responses and rainflow cycle count processing of stress ranges. The procedure was applied to simulate an aluminium patrol vessel in sea conditions corresponding to the sea-keeping trials. Global stress measurements in sea conditions where wave impacts on the hull occurred frequently. Simulated results were compared to these experimental full-scale results. Theoretical results showed reasonable correlation with experimental data.

To reach fusion conditions and control plasma configuration in ITER, a suitable combination of additional heating and current drive systems is necessary. Among them, two Neutral Beam Injectors (NBI) will provide 33 MW hydrogen/deuterium particles electrostatically accelerated to 1 MeV; efficient gas-cell neutralisation at such beam energy requires negative ions, obtained by caesium-catalysed surface conversion of atoms inside the ion source. As ITER NBI requirements have never been simultaneously attained, a Neutral Beam Test Facility (NBTF) was set up at Consorzio RFX (Italy), including two experiments. MITICA is the full-scale NBI prototype with 1 MeV particle energy. SPIDER, with 100 keV particle energy, aims at testing and optimising the full-scale ion source: extracted beam uniformity, negative ion current density (for one hour) and beam optics (beam divergence