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Collisionless shock acceleration of protons in a plasma slab produced in a gas jet by the collision of two laser-driven hydrodynamic shockwaves
No full textWe have recently proposed a new technique of plasma tailoring by laser-driven hydrodynamic shockwaves generated on both sides of a gas jet [Marquès et al., Phys. Plasmas 28, 023103 (2021)]. In a continuation of this numerical work, we study experimentally the influence of the tailoring on proton acceleration driven by a high-intensity picosecond laser in three cases: without tailoring, by tailoring only the entrance side of the picosecond laser, and by tailoring both sides of the gas jet. Without tailoring, the acceleration is transverse to the laser axis, with a low-energy exponential spectrum, produced by Coulomb explosion. When the front side of the gas jet is tailored, a forward acceleration appears, which is significantly enhanced when both the front and back sides of the plasma are tailored. This forward acceleration produces higher-energy protons, with a peaked spectrum, and is in good agreement with the mechanism of collisionless shock acceleration (CSA). The spatiotemporal evolution of the plasma profile is characterized by optical shadowgraphy of a probe beam. The refraction and absorption of this beam are simulated by post-processing 3D hydrodynamic simulations of the plasma tailoring. Comparison with the experimental results allows estimation of the thickness and near-critical density of the plasma slab produced by tailoring both sides of the gas jet. These parameters are in good agreement with those required for CSA
Mock-ups fabrication by HRP technology with advanced W-alloy monoblocks for DEMO divertor target
No full textTungsten is the primary candidate armour material for the divertor target of the European demonstration fusion power plant. During operation at high temperature, pure tungsten is subject to fracture and recrystallization which results in a loss of strength and worsening of the thermal properties. Additionally, loss-of-coolant accidents with simultaneous air ingress can generate volatile and radioactive tungsten oxides. Advanced W-alloys were developed as alternative and upgrading armour materials of pure tungsten, such as potassium-doped tungsten laminates and self-passivating tungsten alloys. Three mock-ups were manufactured using potassium-doped tungsten laminates, W-10Cr-0.5Y and W-10Cr-0.5Y-0.5Zr as armour materials, each of them consisting of n°4 blocks. The fabrication required optimization and upscaling of the ITER-like process which foresees oxygen-free high conductivity copper as interlayer joined to W-alloy armour block and CuCrZr ITER grade pipe welded to the Cu/W-alloy blocks by hot radial pressing. For quality control of the fabrication steps, non-destructive examination by ultrasonic testing was done on the monoblocks as received, after casting, after hot radial pressing and after high heat flux testing. The results demonstrated that these W-alloys can be used as armour materials of the European demonstration fusion power plant divertor target
Understanding the Best Nutritional Management for Creutzfeldt–Jakob Disease Patients: A Comparison Between East Asian and Western Experiences
Full text link(1) Background: Creutzfeldt–Jakob disease (CJD) is a rare and fatal neurodegenerative disorder caused by the accumulation of an altered prion protein, which usually leads to death within one year after clinical onset. CJD patients usually present with rapid cognitive impairment associated with declines in cerebellar, motor, visual, behavioral, and swallowing functions. Moreover, CJD patients lose their ability to eat and take medications orally very early on in treatment; nevertheless, there are no specific nutritional guidelines for this disease shared worldwide. (2) Methods: This review aims to describe the nutritional outcomes of CJD patients in Western countries to compare them with those described in East Asian countries and then aims to explore the most recent trends in the nutritional management of CJD patients, including some dietary compounds that present neuroprotective effects. (3) Results: In Japan’s, Taiwan’s, and China’s healthcare systems, CJD patients receive intensive life-sustaining treatment that prolongs their survival (i.e., artificial feeding); conversely, in Western countries, intensive life-sustaining treatments like tube feeding are not commonly provided to CJD patients. (4) Conclusions: It is difficult to pinpoint the reasons for these discrepancies around CJD palliative care supply, but it is clear that specific nutritional guidelines may directly improve the nutritional management of CJD patients and thus allow their families and caregivers to ensure the best end-of-life care for these patients
Studies of the CEA Design Proposals for EU-DEMO Magnets
No full textThe paper gives an overview of the latest magnet design activities at CEA for the EU-DEMO Magnet Systems. It explains the latest changes in design constraints, inputs and definitions, the updates that have been implemented in the design tools, and shows the latest CEA proposed design for the TF magnet. We will discuss the recent updates in the TF and PF design tools which were used in 2022 and 2023. In particular, the tools have evolved to include additional constraints or operating points like possible sub-cooling of the coils or synchronous discharge of the axisymmetric PF/CS system. The electromagnetic coupling of the TF coils with coil case and radial plates is also discussed during a fast safety discharge, along with energy extraction and deposition sharing. Furthermore, a new 2D TF mechanical model is presented that permits to make a fast iteration with design tools and optimize the radial build. Finally, the paper also includes an update on the CEA TF conductor qualification sample, describing in particular the latest results obtained in the Twente Press
ALICE upgrades during the LHC Long Shutdown 2
No full textA Large Ion Collider Experiment (ALICE) has been conceived and constructed as a heavy-ion experiment at the LHC. During LHC Runs 1 and 2, it has produced a wide range of physics results using all collision systems available at the LHC. In order to best exploit new physics opportunities opening up with the upgraded LHC and new detector technologies, the experiment has undergone a major upgrade during the LHC Long Shutdown 2 (2019–2022). This comprises the move to continuous readout, the complete overhaul of core detectors, as well as a new online event processing farm with a redesigned online-offline software framework. These improvements will allow to record Pb-Pb collisions at rates up to 50 kHz, while ensuring sensitivity for signals without a triggerable signature
Low-cost architecture for iron-based coated conductors
Full text linkThe design of iron-based coated conductors (IBS-CC) with a simplified architecture is possible thanks to the material properties that allow for milder requirements on the template crystalline quality. With respect to the state-of-the-art multilayered layout, it is possible to use a single buffer layer that remains necessary for protection and to promote the oriented growth of the superconducting film. In this work, Fe(Se,Te) films are grown via pulsed laser deposition (PLD) on commercial tapes using a single, chemically deposited, CeO2-based buffer layer, and interesting properties are obtained. In detail, the preparation and characterization of the buffer layer is presented, along with the detailed analysis of the Fe(Se,Te) current transport properties. The samples show superconducting transitions with Tc0 around 12 K and critical current densities of ∼0.1 MA cm−2 at 4.2 K at zero field. These results show that the design of a low-cost IBS-CC with a single chemical buffer layer is possible
The Mu2e Digitizer ReAdout Controller (DiRAC): Characterization and radiation hardness
No full textThe Mu2e experiment at Fermilab will search for the neutrino-less coherent conversion of a muon into an electron in the field of a nucleus. Mu2e detectors comprise a straw tracker, an electromagnetic calorimeter and a veto for cosmic rays. The calorimeter employs 1348 Cesium Iodide crystals readout by silicon photo-multipliers and fast front-end, and digitization electronics. The digitization board is named DiRAC (Digitizer ReAdout Controller) and 140 cards are needed for the readout of the full calorimeter. The DiRACs are hosted in crates located on the external surface of calorimeter disks, inside the detector solenoid cryostat and must sustain very high radiation and magnetic field so it was necessary to fully qualify it. Several version of prototypes were validated for operation in a high-vacuum (10−4 Torr) and under a 1T magnetic field. An extensive radiation hardness qualification campaign, carried out with photons, 14 MeV neutron beams, and 200 MeV protons, certified the DiRAC design to sustain doses up to 12 krad, neutron fluences up to ∼10111MeV neq/cm2, and very low occurrences of single-event effects. The qualification campaigns and quality assurance procedures will be reviewed
Estimation of plant pollution removal capacity based on intensive air quality measurements
No full textThis study investigated the role of present vegetation in improving air quality in Bucharest (Romania) by analyzing six years of air quality data (PM10 and NO2) from multiple monitoring stations. The target value for human health protection is regularly exceeded for PM10 and not for NO2 over time. Road traffic has substantially contributed (over 70%) to ambient PM10 and NO2 levels. The results showed high seasonal variations in pollutant concentrations, with a pronounced effect of vegetation in reducing PM10 and NO2 levels. Indeed, air quality improvements of 7% for PM10 and 25% for NO2 during the growing season were reported. By using Principal Component Analysis and pollution data subtraction methodology, we have disentangled the impact of vegetation on air pollution and observed distinct annual patterns, particularly higher differences in PM10 and NO2 concentrations during the warm season. Despite limitations such as a lack of full tree inventory for Bucharest and a limited number of monitoring stations, the study highlighted the efficiency of urban vegetation to mitigate air pollution
Analysis of the Thermal Runaway Mitigation Performances of Dielectric Fluids During Overcharge Abuse Tests of Lithium-Ion Cells with Lithium Titanate Oxide Anodes
Full text linkLithium titanate oxide cells are gaining attention in electric vehicle applications due to their ability to support high-current charging and their enhanced thermal stability. However, despite these advantages, safety concerns, particularly thermal runaway, pose significant challenges during abuse conditions such as overcharging. In this study, we investigated the effectiveness of various dielectric fluids in mitigating thermal runaway during overcharge abuse tests of cylindrical LTO cells with a capacity of 10 Ah. The experimental campaign focused on overcharging fully charged cells (starting at 100% State of Charge) at a current of 40A (4C). The tests were conducted under two conditions: the first benchmark test involved a cell exposed to air, while the subsequent tests involved cells submerged in different dielectric fluids. These fluids included two perfluoropolyether fluorinated fluids (PFPEs) with boiling points of 170 °C and 270 °C, respectively, a synthetic ester, and a silicone oil. The results were analyzed to determine the fluids’ ability to delay possible thermal runaway and prevent catastrophic failures. The findings demonstrate that some dielectric fluids can delay thermal runaway, with one fluid showing superior performance with respect to the others in preventing fire during thermal runaway. The top-performing fluid was further evaluated in a simulated battery pack environment, confirming its ability to mitigate thermal runaway risks. These results provide important insights for improving the safety of battery systems in electric vehicles
Generalized uncertainty principle theories and their classical interpretation
Full text linkIn this work, we show that it is possible to define a classical system associated with a Generalized Uncertainty Principle (GUP) theory via the implementation of a consistent symplectic structure. This provides a solid framework for the classical Hamiltonian formulation of such theories and the study of the dynamics of physical systems in the corresponding deformed phase space. By further characterizing the functions that govern non-commutativity in the configuration space using the algebra of angular momentum, we determine a general form for the rotation generator in these theories and crucially, we show that, under these conditions, unlike what has been previously found in the literature at the quantum level, this requirement does not lead to the superselection of GUP models at the classical level. Finally, we postulate that a properly defined GUP theory can be correctly interpreted classically if and only if the corresponding quantum commutators satisfy the Jacobi identities, identifying those quantization prescriptions for which this holds true