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Pellet injection represents, to date, the most promising option for core fuelling of the EU-DEMO tokamak. Simulations with the HPI2 pellet ablation/deposition code indicate, however, that sufficiently deep fuel deposition requires injection from the High Field Side (HFS) at velocities ≳1 km/s. Two complementary inboard injection schemes are being explored: one makes use of guide tubes with curvature radii ≥6 m in the attempt of preserving pellet integrity at speeds of ˜1 km/s, the other is investigating the feasibility of injecting high-speed (˜3 km/s) pellets along “direct line of sight” (DLS) trajectories, from either the HFS or a vertical port. Options using quasi-vertical DLS paths routed across the upper vertical port have been explored first, as they can be more easily integrated, Unfortunately, the radial position of the available vertical access (≳9 m from the machine axis) turns out to be unfavorable; further simulations with the HPI2 code predict indeed that vertical injection may be effective only if pellets trajectories are well inboard the magnetic axis. High-speed injection through oblique inboard “DLS” paths, not interfering with the Central Solenoid (CS), are instead predicted to yield good performance, provided that the injection location is ≲2.5 m from the equatorial mid-plane. The angular spread of high-speed free-flight pellets, recently measured using an existing facility, turns out to be enclosed within ˜ 0.7°. This scatter cone may require significant cut off volume of the Breeding Blanket (BB). Moreover, DLS in-vessel conical penetrations may increase the neutron flux outside of the bio-shield, and also result in a significant heat load in the cryogenic pellet source. These issues are being investigated, to identify suitable shielding strategies; preliminary results are reported. The suitability of straight guide tubes to reduce the scatter cone, and hence the corresponding open cross section on BB penetration and the neutron streaming, will be explored as a further step. © 2019 Elsevier B.V.

The injection of high-speed cryogenic pellets made of frozen hydrogen-isotopes, represents to date the most effective method to fuel magnetically confined thermonuclear fusion plasmas. Moreover, the injection of very large pellets composed of cryogenic solid of some suitable impurity (typically a noble-gas such as H2, Ne, or H2/Ne, D2/Ne mixtures), shattered in relatively small fragments just before entering the plasma, seems to be the most promising method to reduce the damage risks for the plasma-facing components in case of a plasma disruption. This technology, known as "Shattered Pellet Injection" (SPI), allows to spread out the plasma energy and mitigate possible damage to the in-vessel components, as well as to densify the plasma to suppress the formation of runaway electrons, and/or dissipate their energy. Several techniques to produce and launch cryogenic pellets have been investigated in the past decades. "Pipe gun" injectors are reliable and relatively simple devices are still commonly used today. They make use of single- or two-stage pneumatic light-gas guns to accelerate the pellet at high speeds. In these injectors, the cryogenic pellets are formed “in situ” (i.e., inside the launching barrel), by de-sublimating them directly from the gas phase, i.e., at temperatures and pressures below those of the triple point. The simplest case is pure deuterium pellets (T < 18.7 K, P < 171.3 hPa). The production of good quality solid deuterium, capable of withstanding the mechanical stress during the acceleration of the pellets, is a key issue. To this end the phase transition of deuterium from gas to solid (and vice versa) is modeled with extensive molecular-dynamics (MD) simulations. Moreover, the solid growth from the gas phase is simulated in an ample range of temperatures and pressures, to find the best compromise between growth velocity and mechanical properties of the resulting solid system.

In this work, we present an overview on the development and integration in ENEAGRID of some tools to evaluate brand importance of homogeneous financial instruments, such as cryptocurrencies. Our system is based on the analysis of textual data, such as tweets or online news. A collaborative environment called Web Crawling Virtual Laboratory allows data retrieval from the web. Below we describe this virtual lab and the ongoing activity aimed at adding a new feature, to allow news and social media crawling. We also provide some details about the integration in ENEAGRID of a new measure of brand importance and its Virtual Laboratory, namely the Semantic Brand Score. We aim to test the first version of this new virtual environment on Twitter data, to rank digital currencies.

We provide an overview on the development and the integration in ENEAGRID of a web crawling tool to retrieve data from the Web, manage and display it, and extract relevant information. We collected all these instruments in a collaborative environment called Web Crawling Virtual Laboratory, offering a GUI to operate remotely. Finally, we describe an ongoing activity on semantic crawling and data analysis to discover trends and correlations in finance.

The four-barrel, two-stage gun Ignitor Pellet Injector (IPI) was developed in collaboration between ENEA and ORNL. The prototype injector is presently located at Oak Ridge (TN, USA), and is normally operated locally through a control and data acquisition system developed in LabVIEW. More recently, a remote-control system has been set up, based on RealVNC®, which allows to operate the IPI from a control room in Italy. Tools for data transfer and storage into ENEA ICT area have also been provided. A Staging, Storage and Sharing system, named E3S, developed using OwnCloud as architectural component, is used for file synchronization and sharing of the data acquired by the diagnostic systems. It provides a homogeneous platform able to store and share heterogeneous data produced by many data acquisition systems in large nuclear fusion experiments. This paper reports about the implementation of the IPI remote control, and presents the application of E3S to this specific case, allowing easy storage and sharing of experimental data onto a wide-area distributed file-system, as well as remote data access via web-services based on MDS+ tool, integrated with MySQL metadata. A performance analysis of the architectural components is also introduced.

ITER fueling and Edge Localized Mode (ELM) pacing pellets will be created by punching and chambering pellets with a solenoid operated cutter from an extrudate formed by a twin-screw extruder. The cut pellets are then accelerated down a flight tube by a fast pneumatic valve. The impurity pellets are formed in-situ with a pipe gun technique and accelerated down a flight tube with the same pneumatic valve design. © 2015 IEEE.

The Ignitor Program maintains the objective of approaching D-T ignition conditions by incorporating systematical advances made with relevant high field magnet technology and with experiments on high density well confined plasmas in the present machine design. An additional objective is that of charting the development of the high field line of experiments that goes from the Alcator machine to the ignitor device. The rationale for this class of experiments, aimed at producing poloidal fields with the highest possible values (compatible with proven safety factors of known plasma instabilities) is given. On the basis of the favourable properties of high density plasmas produced systematically by this line of machines, the envisioned future for the line, based on novel high field superconducting magnets, includes the possibility of investigating more advanced fusion burn conditions than those of the D-T plasmas for which Ignitor is designed. Considering that a detailed machine design has been carried out (Coppi et al 2013 Nucl. Fusion 53 104013), the advances made in different areas of the physics and technology that are relevant to the Ignitor project are reported. These are included within the following sections of the present paper: main components issues, assembly and welding procedures; robotics criteria; non-linear feedback control; simulations with three-dimensional structures and disruption studies; ICRH and dedicated diagnostics systems; anomalous transport processes including self-organization for fusion burning regimes and the zero-dimensional model; tridimensional structures of the thermonuclear instability and control provisions; superconducting components of the present machine; envisioned experiments with high field superconducting magnets. © 2015 IAEA.

An existing pipe gun test facility at ORNL was used for an experimental study of propellant gas loads required for ITER-relevant pellet injection, with the key objective of determining the minimal amount of gas required for optimal pellet speeds. Two pellet sizes were tested, with nominal 4.4 and 3.2 mm diameters comparable to pellets planned for fueling and ELM pacing in ITER, respectively. A novel scheme was used to freeze solid pellets from room temperature gas; this facilitated operations at higher temperatures (14.5 to 16.5 K, similar to those planned for extruder operations for ITER pellet injectors) and thus lower pellet breakaway pressures and gas loads. Most of the single-shot D2 pellet tests were carried out with a relatively low H2 propellant gas load of ∼0.0133 bar-L. Some limited testing was also carried out with a mixed propellant gas that consisted mostly of D2, which is more representative of the gas that will be used for ITER pellet injection. In testing it was found that this reference gas load resulted in pellet speeds in close proximity to a speed limit (∼300 m/s) previously determined in a series of tests with D2 pellets shot through a mock-up of the curved guide tubes planned for the ITER installation (for pellet fueling from the magnetic high-field side). The equipment, operations, and test results are presented and discussed, with emphasis on the relevance for ITER operations.

Medium size HPC clusters play an important role in the HPC landscape in that they provide both the training environment for system scalability and a flexible production field for a large class of numerical problems. In this poster we present CRESCO4, the latest medium size HPC cluster purchased by ENEA, in operation since few months. CRESCO4 is part of a family of HPC systems, all integrated within ENEAGRID, a large infrastructure for cloud computing, which includes all the computational facilities installed at several ENEA sites in Italy.

The scientific goal of the Ignitor experiment is to approach, for the first time, the ignition conditions of a magnetically confined D-T plasma. The IGNIR collaboration between Italy and Russia is centred on the construction of the core of the Ignitor machine in Italy and its installation and operation within the Triniti site (Troitsk). A parallel initiative has developed that integrates this programme, involving the study of plasmas in which high-energy populations are present, with ongoing research in high-energy astrophysics, with a theory effort involving the National Institute for High Mathematics, and with INFN and the University of Pisa for the development of relevant nuclear and optical diagnostics. The construction of the main components of the machine core has been fully funded by the Italian Government. Therefore, considerable attention has been devoted towards identifying the industrial groups having the facilities necessary to build these components. An important step for the Ignitor programme is the adoption of the superconducting MgB2 material for the largest poloidal field coils (P14) that is compatible with the He-gas cooling system designed for the entire machine. The progress made in the construction of these coils is described. An important advance has been made in the reconfiguration of the cooling channels of the toroidal magnet that can double the machine duty cycle. A facility has been constructed to test the most important components of the ICRH system at full scale, and the main results of the tests carried out are presented. The main physics issues that the Ignitor experiment is expected to face are analysed considering the most recent developments in both experimental observations and theory for weakly collisional plasma regimes. Of special interest is the I-regime that has been investigated in depth only recently and combines advanced confinement properties with a high degree of plasma purity. This is a promising alternative to the high-density L-regime that had been observed by the Alcator experiment and whose features motivated the Ignitor project. The provisions that are incorporated in the machine design, and in that of the plasma chamber in particular, in order to withstand or prevent the development of macroscopic instabilities with deleterious amplitudes are presented together with relevant analyses. © 2013 IAEA, Vienna.