Influence of the magnetic filter field topology on the beam divergence at the ELISE test facility

The ELISE test facility hosts a RF negative ion source, equipped with an extraction system which should deliver half the current foreseen for the ITER Neutral Beam Injector, keeping the ratio of co-extracted electrons to ions below 1. An important tool for the suppression of the co-extracted electrons is the magnetic filter field, produced by a current flowing in the plasma grid, the first grid of the 3 stage extraction system. To boost the source performances new concepts for the production of the magnetic filter field have been tested, combining the existing system with permanent magnets attached on the source walls. The topologies of these new magnetic configurations influence the beam particles trajectories in the extraction region, with consequences for the overall beam optics. These effects will be characterized in this article by studying the angular distribution of the beam particles, as measured by the Beam Emission Spectroscopy (BES) diagnostic. The behavior of the beam will be studied also through the measurements of the currents flowing on the grounded grid (the third grid) and on the grid holder box surrounding its exit. The main finding is that the broader component of the beam increases when the magnetic field is strengthened by permanent magnets, i.e. in the cases in which most of the co-extracted electrons are suppressed.Comment: 7 pages, 4 figures. Contributed paper for the NIBS 2016 conference. Accepted manuscrip

Beam characterization by means of emission spectroscopy in the ELISE test facility

The ELISE test facility at IPP Garching hosts a RF H-/D- ion source and an acceleration system. Its target is to demonstrate the performance foreseen for the ITER NBI system in terms of extracted current density (H/D), fraction of co-extracted electrons and pulse duration. The size of the ELISE extraction area is half that foreseen for the ITER NBI. This paper presents a detailed study of the ELISE beam divergence and uniformity. In particular, it was possible to describe the beam as the sum of two components at very different divergence: about 2{\deg} vs. 5{\deg}{\div}7{\deg}. As test cases, the beam properties have been measured as function of two source parameters. The first one is the current flowing through the grid facing the plasma, the Plasma Grid, in order to generate the magnetic filter field. The second one is the bias current flowing between the Plasma Grid and the source walls. Both the filter field and the bias current influence the fraction of co-extracted electrons, but also the properties of the plasma just in front of the extraction system and the beam properties. The divergence and the uniformity of the beam have been measured by a Beam Emission Spectroscopy (BES) diagnostic; the detailed analysis of the raw spectra collected by BES led to describing the beam with two components of different divergence. This concept has been supported by the information given by thermal imaging of the diagnostic calorimeter. Further support to the proposed beam model has been found in the behavior of the currents flowing in the acceleration system and beamline components; these currents are given by the most divergent (charged) particles of the beam.Comment: 15 pages, 8 figures. Accepted manuscript (embargo expired

First hydrogen operation of NIO1: characterization of the source plasma by means of an optical emission spectroscopy diagnostic

NIO1 is a compact and flexible radiofrequency H- ion source, developed by Consorzio RFX and INFN-LNL. Aim of the experimentation on NIO1 is the optimization of both the production of negative ions and their extraction and beam optics. In the initial phase of its commissioning, NIO1 was operated with nitrogen, but now the source is regularly operated also with hydrogen. To evaluate the source performances an optical emission spectroscopy diagnostic was installed. The system includes a low resolution spectrometer in the spectral range of 300-850 nm and a high resolution (50 pm) one, to study respectively the atomic and the molecular emissions in the visible range. The spectroscopic data have been interpreted also by means of a collisional-radiative model developed at IPP Garching. Besides the diagnostic hardware and the data analysis methods, the paper presents the first plasma measurements across a transition to the full H mode, in a hydrogen discharge. The characteristic signatures of this transition in the plasma parameters are described, in particular the sudden increase of the light emitted from the plasma above a certain power threshold.Comment: 3 pages, 2 figures. Contributed paper for the ICIS 2015 conference. Accepted manuscrip

Grey zones in the supportive treatments of cardiac amyloidosis

Recent advances in the diagnosis and treatment of cardiac amyloidosis (CA) have translated into a longer life expectancy of patients and more challenging clinical scenarios. Compared to the past, patients with CA and heart failure (HF) currently encountered in clinical practice are a more heterogeneous population and require tailored strategies. The perception of CA as a treatable disease has opened new possibilities for the management of these patients, but many grey areas remain to be explored. The aim of this review is to provide practical suggestions for daily clinical activity in the management of challenging scenarios in CA, including the effectiveness and tolerability of evidence-based HF medication; rate vs. rhythm control in atrial fibrillation, thromboembolic risk, and anticoagulation therapies; replacement of severe aortic valve stenosis; the impact of implantable cardioverter defibrillator on survival; and the usefulness of cardiac resynchronization therapy

Nanostructured 3C-SiC on Si by a network of (111) platelets: a fully textured film generated by intrinsic growth anisotropy

In this paper, we address the unique nature of fully textured, high surface-to-volume 3C-SiC films, as produced by intrinsic growth anisotropy, in turn generated by the high velocity of the stacking fault growth front in two-dimensional (111) platelets. Structural interpretation of high resolution scanning electron microscopy and transmission electron microscopy data is carried out for samples grown in a hot-wall low-pressure chemical vapour deposition reactor with trichlorosilane and ethylene precursors, under suitable deposition conditions. By correlating the morphology and the X-ray diffraction analysis we also point out that twinning along (111) planes is very frequent in such materials, which changes the free-platelet configuration

Maternal Low-Protein Diet Deregulates DNA Repair and DNA Replication Pathways in Female Offspring Mammary Gland Leading to Increased Chemically Induced Rat Carcinogenesis in Adulthood

Studies have shown that maternal malnutrition, especially a low-protein diet (LPD), plays a key role in the developmental mechanisms underlying mammary cancer programming in female offspring. However, the molecular pathways associated with this higher susceptibility are still poorly understood. Thus, this study investigated the adverse effects of gestational and lactational low protein intake on gene expression of key pathways involved in mammary tumor initiation after a single dose of N-methyl-N-nitrosourea (MNU) in female offspring rats. Pregnant Sprague–Dawley rats were fed a normal-protein diet (NPD) (17% protein) or LPD (6% protein) from gestational day 1 to postnatal day (PND) 21. After weaning (PND 21), female offspring (n = 5, each diet) were euthanized for histological analysis or received NPD (n = 56 each diet). At PND 28 or 35, female offspring received a single dose of MNU (25 mg/kg body weight) (n = 28 each diet/timepoint). After 24 h, some females (n = 10 each diet/timepoint) were euthanized for histological, immunohistochemical, and molecular analyses at PDN 29 or 36. The remaining animals (n = 18 each diet/timepoint) were euthanized when tumors reached ≥2 cm or at PND 250. Besides the mammary gland development delay observed in LPD 21 and 28 groups, the gene expression profile demonstrated that maternal LPD deregulated 21 genes related to DNA repair and DNA replication pathways in the mammary gland of LPD 35 group after MNU. We further confirmed an increased γ-H2AX (DNA damage biomarker) and in ER-α immunoreactivity in mammary epithelial cells in the LPD group at PND 36. Furthermore, these early postnatal events were followed by significantly higher mammary carcinogenesis susceptibility in offspring at adulthood. Thus, the results indicate that maternal LPD influenced the programming of chemically induced mammary carcinogenesis in female offspring through increase in DNA damage and deregulation of DNA repair and DNA replication pathways. Also, Cidea upregulation gene in the LPD 35 group may suggest that maternal LPD could deregulate genes possibly leading to increased risk of mammary cancer development and/or poor prognosis. These findings increase the body of evidence of early-transcriptional mammary gland changes influenced by maternal LPD, resulting in differential response to breast tumor initiation and susceptibility and may raise discussions about lifelong prevention of breast cancer risk.Fil: Zapaterini, Joyce R.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Fonseca, Antonio R. B.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Bidinotto, Lucas T.. Barretos Cancer Hospital; Brasil. Barretos School of Health Sciences; BrasilFil: Colombelli, Ketlin T.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Rossi, André L. D.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Kass, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Justulin, Luis A.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Barbisan, Luis F.. Universidade Estadual Paulista Julio de Mesquita Filho; Brasi

Thermodynamic driving force in the formation of hexagonal-diamond Si and Ge nanowires

The metastable hexagonal-diamond phase of Si and Ge (and of SiGe alloys) displays superior optical properties with respect to the cubic-diamond one. Based on first-principle calculations we show that the surface energy of the typical facets exposed in Si and Ge nanowires is lower in the hexagonal-diamond phase than in the cubic one. By exploiting a synergic approach based also on a recent state-of-the-art interatomic potential and on a simple geometrical model, we investigate the relative stability of nanowires in the two phases up to few tens of nm in radius, highlighting the surface-related driving force and discussing its relevance in recent experiments. We also explore the stability of Si and Ge core-shell nanowires with hexagonal cores (made of GaP for Si nanowires, of GaAs for Ge nanowires). In this case, the stability of the hexagonal shell over the cubic one is also favored by the energy cost associated with the interface linking the two phases. Interestingly, our calculations indicate a critical radius of the hexagonal shell much lower than the one reported in recent experiments, indicating the presence of a large kinetic barrier allowing for the enlargement of the wire in a metastable phase

Start of SPIDER operation towards ITER neutral beams

Heating Neutral Beam (HNB) Injectors will constitute the main plasma heating and current drive tool both in ITER and JT60-SA, which are the next major experimental steps for demonstrating nuclear fusion as viable energy source. In ITER, in order to achieve the required thermonuclear fusion power gain Q=10 for short pulse operation and Q=5 for long pulse operation (up to 3600s), two HNB injectors will be needed [1], each delivering a total power of about 16.5 MW into the magnetically-confined plasma, by means of neutral hydrogen or deuterium particles having a specific energy of about 1 MeV. Since only negatively charged particles can be efficiently neutralized at such energy, the ITER HNB injectors [2] will be based on negative ions, generated by caesium-catalysed surface conversion of atoms in a radio-frequency driven plasma source. A negative deuterium ion current of more than 40 A will be extracted, accelerated and focused in a multi-aperture, multi-stage electrostatic accelerator, having 1280 apertures (~ 14 mm diam.) and 5 acceleration stages (~200 kV each) [3]. After passing through a narrow gas-cell neutralizer, the residual ions will be deflected and discarded, whereas the neutralized particles will continue their trajectory through a duct into the tokamak vessels to deliver the required heating power to the ITER plasma for a pulse duration of about 3600 s. Although the operating principles and the implementation of the most critical parts of the injector have been tested in different experiments, the ITER NBI requirements have never been simultaneously attained. In order to reduce the risks and to optimize the design and operating procedures of the HNB for ITER, a dedicated Neutral Beam Test Facility (NBTF) [4] has been promoted by the ITER Organization with the contribution of the European Union\u2019s Joint Undertaking for ITER and of the Italian Government, with the participation of the Japanese and Indian Domestic Agencies (JADA and INDA) and of several European laboratories, such as IPP-Garching, KIT-Karlsruhe, CCFE-Culham, CEA-Cadarache. The NBTF, nicknamed PRIMA, has been set up at Consorzio RFX in Padova, Italy [5]. The planned experiments will verify continuous HNB operation for one hour, under stringent requirements for beam divergence (< 7 mrad) and aiming (within 2 mrad). To study and optimise HNB performances, the NBTF includes two experiments: MITICA, full-scale NBI prototype with 1 MeV particle energy and SPIDER, with 100 keV particle energy and 40 A current, aiming at testing and optimizing the full-scale ion source. SPIDER will focus on source uniformity, negative ion current density and beam optics. In June 2018 the experimental operation of SPIDER has started