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Neutral beam injection is one of the most important methods of plasma heating in thermonuclear fusion experiments, allowing the attainment of fusion conditions as well as driving the plasma current. Neutral beams are generally produced by electrostatically accelerating ions, which are neutralised before injection into the magnetised plasma. At the particle energy required for the most advanced thermonuclear devices and particularly for ITER, neutralisation of positive ions is very inefficient so that negative ions are used. The present paper is devoted to the description of the phenomena occurring when a high-power multi-ampere negative ion beam travels from the beam source towards the plasma. Simulation of the trajectory of the beam and of its features requires various numerical codes, which must take into account all relevant phenomena. The leitmotiv is represented by the interaction of the beam with the background gas. The main outcome is the partial neutralisation of the beam particles, but ionisation of the background gas also occurs, with several physical and technological consequences. Diagnostic methods capable of investigating the beam properties and of assessing the relevance of the various phenomena will be discussed. Examples will be given regarding the measurements collected in the small flexible NIO1 source and regarding the expected results of the prototype of the neutral beam injectors for ITER. The tight connection between measurements and simulations in view of the operation of the beam is highlighted.

In NIO1, a compact H - ion source installed at RFX operated in continuous mode, gas conditioning was needed to improve results in Cs-free regimes (up to a current density about 25 or 30 A/m 2 ). Installation of a cesium oven gave an additional increase of current, progressively limited also by a rapid overcesiation: we observed an average density about 50 A/m 2 (with a peak of 67 A/m 2 ). Obtained beam optics is briefly compared with simulations and previous results in the Cs-free regime in similar conditions (as source voltage, often set below or equal 11 kV). In both regimes, central beamlet apparent density is larger, possibly because of a narrow bias plate mask, now enlarged. Further improvements for Cs-based regime include a moderate oven reservoir temperature, careful tuning and a substantial increase of beam voltage, and power handling capability.

The aim of the study was to estimate the prevalence of rotavirus disease in children <5 years old in Tirana, Albania, and to monitor and characterize the rotavirus genotypes. Rotavirus was detected in 21 % of samples, more frequently in children under 2 years of age, which accounted for 80.8 % of all positive cases. Among all rotavirus-positive samples collected, G4P[8] was the most prevalent genotype (38 %), followed by G1P[8] (36.6 %). The use of safe and effective rotavirus vaccines for the prevention of severe diarrhoea and the reduction of treatment costs will be of great importance for Albania.

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 compact radio frequency negative ion source NIO1 (Negative Ion Optimization phase 1) has been designed, built and operated by Consorzio RFX and INFN-LNL in order to study and optimize the production and acceleration of H- ions in continuous operation. In 2020 Cs was evaporated in the source to increase the total extracted ion current. After an initial reduction of extracted electron to ion ratio and subsequently an increase of extracted negative ion current, the source performances progressively worsened, because of the excessive amount of Cs evaporated in the source; the extracted electron to ion ratio increased from below 1 to more than 10, while ion current density reduced from max. 67 A/m2 ion current to not more than 30 A/m2). The paper presents the experimental observations collected during Cs evaporation (reduction of plasma light, Cs emission and H\\(\\beta\\)/H\\(\\gamma\\) ratio, etc.) that can help stopping the process before an excessive amount of Cs is introduced in the source. The paper also reports the cleaning techniques tested to remove the Cs excess by the action of hydrogen or argon plasmas; while argon was predictably more effective in surface sputtering, a 3 h Ar plasma treatment was not sufficient to recover from overcesiation.

We have previously shown that manganese enhances L‐dihydroxyphenylanine (L‐DOPA) toxicity to PC12 cells in vitro. The supposed mechanism of manganese enhancing effect [an increase in L‐DOPA and dopamine (DA) auto‐oxidation] was studied using microdialysis in the striatum of freely moving rats. Systemic L‐DOPA [25 mg kg−1 intraperitoneally (i.p.) twice in a 12 h interval] significantly increased baseline dialysate concentrations of L‐DOPA, dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and uric acid, compared to controls. Conversely, DA and ascorbic acid concentrations were significantly decreased. A L‐DOPA oxidation product, presumptively identified as L‐DOPA semiquinone, was detected in the dialysate. The L‐DOPA semiquinone was detected also following intrastriatal infusion of L‐DOPA. In rats given L‐DOPA i.p., intrastriatal infusion of N‐acetylcysteine (NAC) significantly increased DA and L‐DOPA dialysate concentrations and lowered those of L‐DOPA semiquinone; in addition, NAC decreased DOPAC+HVA and uric acid dialysate concentrations. In rats given L‐DOPA either systemically or intrastriatally, intrastriatal infusion of manganese decreased L‐DOPA dialysate concentrations and greatly increased those of L‐DOPA semiquinone. These changes were inhibited by NAC infusion. These findings demonstrate that auto‐oxidation of exogenous L‐DOPA occurs in vivo in the rat striatum. The consequent reactive oxygen species generation may account for the decrease in dialysate DA and ascorbic acid concentrations and increase in enzymatic oxidation of xanthine and DA. L‐DOPA auto‐oxidation is inhibited by NAC and enhanced by manganese. These results may be of relevance to the L‐DOPA long‐term therapy of Parkinson's disease. British Journal of Pharmacology (2000) 130, 937–945; doi:10.1038/sj.bjp.0703379

The experimental fusion reactor ITER will feature two (or three) heating neutral beam injectors (NBI) capable of delivering 33(or 50) MW of power into the plasma. A NBI consists of a plasma source for production of negative ions (extracted negative ion current up to 329 A/m 2 in H and 285 A/m 2 in D) then accelerated up to 1 MeV for one hour. The negative ion beam is neutralized, and the residual ions are electrostatically removed before injection. The beamline was designed for a beam divergence between 3 and 7 mrad. The ion source in ITER NBIs relies on RF-driven, Inductively-Coupled Plasmas (ICP), based on the prototypes developed at IPP Garching; RF-driven negative-ion beam sources have never been employed in fusion devices up to now. The recent results of SPIDER, the full size ITER NBI ion source operating at NBTF in Consorzio RFX, Padova, measure a beamlet divergence minimum of 12mrad and highlighted beam spatial non-uniformity. SPIDER results confirmed the experimental divergence found in smaller prototype sources, which is larger compared to filament-arc ion sources. Although prototype experiments have shown that the extracted current requirement can be achieved with minor design improvements, the beamlet divergence is expected to marginally achieve the design value of 7 mrad, which in multi-grid long accelerators results in unexpected heat loads over the accelerator grids. A contributor to the beam divergence is the energy/temperature of the extracted negative ions, so it is believed that plasma differences between the two source types play a role. Research is focused on the plasma parameters in the ion source. One RF driver, identical to the ones used in SPIDER, installed in a relatively small-scale experimental set-up, inherently more flexible than large devices, is starting operations devoted to the investigation of the properties of RF-generated plasmas, so as to contribute to the assessment of negative ion precursors, and of their relationship with the plasma parameters, particularly when enhancing plasma confinement. The scientific questions, that have arisen from the preliminary results of SPIDER, guided the design of the test stand, which are described in this contribution, together with the diagnostic systems and related simulation tools. The test stand, which shares with the larger experiment all the geometrical features and constraints, will allow technological developments and optimized engineering solutions related to the ICP design for the ITER NBIs.

Consorzio RFX and INFN-LNL have designed, built and operated the compact radiofrequency negative ion source NIO1 (Negative Ion Optimization phase 1) with the aim of studying the production and acceleration of H- ions. In particular, NIO1 was designed to keep plasma generation and beam extraction continuously active for several hours. Since 2020 the production of negative ions at the plasma grid (the first grid of the acceleration system) has been enhanced by a Cs layer, deposited though active Cs evaporation in the source volume. For the negative ion sources applied to fusion neutral beam injectors, it is essential to keep the beam current and the fraction of co-extracted electrons stable for at least 1 h, against the consequences of Cs sputtering and redistribution operated by the plasma. The paper presents the latest results of the NIO1 source, in terms of caesiation process and beam performances during continuous (6{\\div}7 h) plasma pulses. Due to the small dimensions of the NIO1 source (20 x (diam.)10 cm), the Cs density in the volume is high (10^15 \\div 10^16 m^-3) and dominated by plasma-wall interaction. The maximum beam current density and minimum fraction of co-extracted electrons were respectively about 30 A/m^2 and 2. Similarly to what done in other negative ion sources, the plasma grid temperature in NIO1 was raised for the first time, up to 80 {\\deg}C, although this led to a minimal improvement of the beam current and to an increase of the co-extracted electron current.

Recent advances in acquisition equipment is providing experiments with growing amounts of precise yet affordable sensors. At the same time an improved computational power, coming from new hardware resources (GPU, FPGA, ACAP), has been made available at relatively low costs. This led us to explore the possibility of completely renewing the chain of acquisition for a fusion experiment, where many high-rate sources of data, coming from different diagnostics, can be combined in a wide framework of algorithms. If on one hand adding new data sources with different diagnostics enriches our knowledge about physical aspects, on the other hand the dimensions of the overall model grow, making relations among variables more and more opaque. A new approach for the integration of such heterogeneous diagnostics, based on composition of deep variational autoencoders, could ease this problem, acting as a structural sparse regularizer. This has been applied to RFX-mod experiment data, integrating the soft X-ray linear images of plasma temperature with the magnetic state. However to ensure a real-time signal analysis, those algorithmic techniques must be adapted to run in well suited hardware. In particular it is shown that, attempting a quantization of neurons transfer functions, such models can be modified to create an embedded firmware. This firmware, approximating the deep inference model to a set of simple operations, fits well with the simple logic units that are largely abundant in FPGAs. This is the key factor that permits the use of affordable hardware with complex deep neural topology and operates them in real-time.