Kinetic formulation and global existence for the Hall-Magneto-hydrodynamics system

This paper deals with the derivation and analysis of the the Hall Magneto-Hydrodynamic equations. We first provide a derivation of this system from a two-fluids Euler-Maxwell system for electrons and ions, through a set of scaling limits. We also propose a kinetic formulation for the Hall-MHD equations which contains as fluid closure different variants of the Hall-MHD model. Then, we prove the existence of global weak solutions for the incompressible viscous resistive Hall-MHD model. We use the particular structure of the Hall term which has zero contribution to the energy identity. Finally, we discuss particular solutions in the form of axisymmetric purely swirling magnetic fields and propose some regularization of the Hall equation

What is behind a summary-evaluation decision?

Research in psychology has reported that, among the variety of possibilities for assessment methodologies, summary evaluation offers a particularly adequate context for inferring text comprehension and topic understanding. However, grades obtained in this methodology are hard to quantify objectively. Therefore, we carried out an empirical study to analyze the decisions underlying human summary-grading behavior. The task consisted of expert evaluation of summaries produced in critically relevant contexts of summarization development, and the resulting data were modeled by means of Bayesian networks using an application called Elvira, which allows for graphically observing the predictive power (if any) of the resultant variables. Thus, in this article, we analyzed summary-evaluation decision making in a computational framewor

The Compact Linear Collider (CLIC) - 2018 Summary Report

The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear $e^+e^-$ collider under development at CERN. Following the CLIC conceptual design published in 2012, this report provides an overview of the CLIC project, its current status, and future developments. It presents the CLIC physics potential and reports on design, technology, and implementation aspects of the accelerator and the detector. CLIC is foreseen to be built and operated in stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3 TeV, respectively. CLIC uses a two-beam acceleration scheme, in which 12 GHz accelerating structures are powered via a high-current drive beam. For the first stage, an alternative with X-band klystron powering is also considered. CLIC accelerator optimisation, technical developments and system tests have resulted in an increased energy efficiency (power around 170 MW) for the 380 GeV stage, together with a reduced cost estimate at the level of 6 billion CHF. The detector concept has been refined using improved software tools. Significant progress has been made on detector technology developments for the tracking and calorimetry systems. A wide range of CLIC physics studies has been conducted, both through full detector simulations and parametric studies, together providing a broad overview of the CLIC physics potential. Each of the three energy stages adds cornerstones of the full CLIC physics programme, such as Higgs width and couplings, top-quark properties, Higgs self-coupling, direct searches, and many precision electroweak measurements. The interpretation of the combined results gives crucial and accurate insight into new physics, largely complementary to LHC and HL-LHC. The construction of the first CLIC energy stage could start by 2026. First beams would be available by 2035, marking the beginning of a broad CLIC physics programme spanning 25-30 years

Repetitive Auto-Triggered Marx Generator for an Ultra Wideband Source

International audienc

Shock wave experiments using a pulsed electron beam to study copper and molybdenum thermoelastic responses

This paper presents the experimental and numerical studies of copper and molybdenum thermomechanical responses using a pulsed source of electrons (3 Mev – 3kA – 60 ns duration). These experiments permit to characterise the dynamic behaviour of materials under high pressure, high temperature and high deformation rate. The rapid deposition of energy generates shock wave motion, which commonly induces inelastic flow or failure. Several experiments have been carried out onto copper and molybdenum targets. The thermomechanical responses have been studied by registering the rear surface motion of the targets using Michelson laser interferometer or the stress history using quartz piezoelectric gage. Numerical computations of energy deposition and shock wave propagation have been performed in order to better understand the dynamics events. The computational constitutive model used for this work was previously developed for metallic material. The numerical results are in almost good accordance with experimental data. The measurement of energy deposition must be improved in order to identify the Grüneisen coefficient of materials

Compact self-loaded Marx generator with integrated pulse-forming line for an ultra-wideband source

International audienceThe paper presents a study on the development of an autonomous, repetitive, pulsed power generator based on a self-loaded Marx generator. Three French entities: CEA, Technix and LGE (Pau University), developed a tightly integrated unit, including a battery pack, an intermediate dc/dc converter, a high-voltage dc/dc converter, a control system, and a high pulse repetition frequency (PRF) Marx generator with its integrated pulse-forming line (PFL). This complete device is able to deliver 150 kV pulses into a 50 $\Omega$ impedance with the following principle characteristics: a rise time of about 650 ps, a fall time lower than 300 ps, a pulse width of about 1.6 ns, a repetition rate of 100 Hz and a burst duration of 10 s. The details of this repetitive peak power generator are presented in this paper. The results of preliminary tests are also included