Publications associées à Novel linear analysis for a gyrotron oscillator based on a spectral approach

Iterative removal of sources to model the turbulent electromotive force

Jennifer Waltraud Schober, Abhijit Bhausaheb Bendre

We describe a novel method to compute the components of dynamo tensors from direct magnetohydrodynamic (MHD) simulations. Our method relies upon an extension and generalization of the standard H & ouml;gbom CLEAN algorithm widely used in radio astronomy to ...

Oxford Univ Press2024

Anomalous‐Chern Steering of Topological Nonreciprocal Guided Waves

Romain Christophe Rémy Fleury, Haoye Qin, Qiaolu Chen, Zhechen Zhang

Nonreciprocal topological edge states based on external magnetic bias have been regarded as the last resort for genuine unidirectional wave transport, showing superior robustness over topological states with preserved time-reversal symmetry. However, fast ...

Wiley2024

Re-design of EU DEMO with a low aspect ratio

Hartmut Zohm

The design point that had been chosen for EU DEMO in 2016 is reviewed here and a modification is proposed with a lower aspect ratio. Previously the same aspect ratio, A, was chosen for EU DEMO as in major tokamak experiments including ITER (A = 3.1), and, ...

2024

A Spectral Ansatz for The Long-Time Homogenization of The Wave Equation

Matthias Ruf, Matthias Benjamin Ruf

Consider the wave equation with heterogeneous coefficients in the homogenization regime. At large times, the wave interacts in a nontrivial way with the heterogeneities, giving rise to effective dispersive effects. The main achievement of the present wor ...

Ecole Polytechnique2024

WILD SOLUTIONS TO SCALAR EULER-LAGRANGE EQUATIONS

Carl Johan Peter Johansson

. We study very weak solutions to scalar Euler-Lagrange equations associated with quadratic convex functionals. We investigate whether W1,1 solutions are necessarily W 1,2 Nash and Schauder applicable. We answer this question positively for a suitable clas ...

Amer Mathematical Soc2024

Experimental observation of topological transition in linear and nonlinear parametric oscillators

Romain Christophe Rémy Fleury, Benjamin Apffel

Parametric oscillators are examples of externally driven systems that can exhibit two stable states with opposite phase depending on the initial conditions. In this work, we propose to study what happens when the external forcing is perturbed by a continuo ...

2024

Shedding light on the MRI-driven dynamo in a stratified shearing box

Abhijit Bhausaheb Bendre

We study the magneto-rotational instability (MRI) dynamo in a geometrically thin disc (H/R < 1) using stratified zero net (vertical) flux shearing box simulations. We find that mean fields and electromotive forces (EMFs) oscillate with a primary frequency ...

2024

A modular multiple frequency inductive link to wirelessly power multiple miniaturized implants

Sandro Carrara, Diego Ghezzi, Gian Luca Barbruni

A modular multiple frequency coils inductive link system to wirelessly provide power for at least a medical implant at an output of a receiving coil, whereby the receiving coil is configured to be implanted in an organism. The modular multiple frequency co ...

2024

The effect of pressure-anisotropy-driven kinetic instabilities on magnetic field amplification in galaxy clusters

Yoan Rappaz, Jennifer Waltraud Schober

Context. The intracluster medium (ICM) is the low-density diffuse gas that fills the space between galaxies within galaxy clusters. It is primarily composed of magnetized plasma, which reaches virial temperatures of up to 10(8) K, probably due to mergers o ...

Edp Sciences S A2024

Terahertz emission from diamond nitrogen-vacancy centers

László Forró, Ferenc Simon, Sándor Kollarics, Bence Gábor Márkus

Coherent light sources emitting in the terahertz range are highly sought after for fundamental research and applications. Terahertz lasers rely on achieving population inversion. We demonstrate the generation of terahertz radiation using nitrogen-vacancy c ...

Amer Assoc Advancement Science2024

Critical degeneracy in a nonlinear hyperbolic equation can produce atypical instability

Charles Stuart

This paper deals with the initial value problem for a semilinear wave equation on a bounded domain and solutions are required to vanish on the boundary of this domain. The essential feature of the situation considered here is that the ellipticity of the sp ...

2024

Modeling and optimization of PCB coils for inductive power transfer systems

Xiaotong Du

The auxiliary power supply for medium voltage converters requires high insulation capability between the source and the load. Inductive power transfer technology, with an air gap between the primary and secondary coil, offers such high insulation capabilit ...

EPFL2024

Task-driven neural network models predict neural dynamics of proprioception: Experimental data, activations and predictions of neural network models

Axel Bisi, Alberto Silvio Chiappa, Alexander Mathis, Alessandro Marin Vargas

Here we provide the neural data, activation and predictions for the best models and result dataframes of our article "Task-driven neural network models predict neural dynamics of proprioception". It contains the behavioral and neural experimental data (cu ...

EPFL Infoscience2024

Biobased surfactant

Jeremy Luterbacher, Stefania Bertella, Anastasiia Komarova, Songlan Sun

The present invention relates to a compound of the general formula (I), and (II)wherein one of R11 and R12 is hydrogen and the other is -CH2-R70, and one of R13 and R14 is hydrogen and the other is -CH2-R71, or wherein one of R11 and R12 is hydrogen and th ...

2024

A graph convolutional autoencoder approach to model order reduction for parametrized PDEs

Jan Sickmann Hesthaven, Federico Pichi

The present work proposes a framework for nonlinear model order reduction based on a Graph Convolutional Autoencoder (GCA-ROM). In the reduced order modeling (ROM) context, one is interested in obtaining real -time and many-query evaluations of parametric ...

Academic Press Inc Elsevier Science2024

Rotating spokes, potential hump and modulated ionization in radio frequency magnetron discharges

Liang Xu, Haomin Sun

In this work, the transition from the gradient drift instability (GDI) into an m = 1 rotating spoke in the radio frequency magnetron discharge was studied by means of the two-dimensional axial-azimuthal (z - y) particle-in-cell/Monte Carlo collision method ...

Iop Publishing Ltd2023

Modelling of nonneutral plasmas trapped by electric and magnetic fields relevant to gyrotron electron guns

Guillaume Michel Le Bars

Gyrotrons are a class of high-power vacuum-electronics microwave sources, which are envisioned to play an important role in the domain of magnetically confined fusion plasmas. Indeed, only gyrotrons are capable of producing continuous electromagnetic waves ...

EPFL2023

First self-consistent simulations of trapped electron clouds in a gyrotron gun and comparison with experiments

Stefano Alberti, Jean-Philippe Hogge, Joaquim Loizu Cisquella, Ioannis Pagonakis, Jérémy Genoud, Francesco Romano

We report on the initial validation of the novel code FENNECS, which simulates the spontaneous formation of trapped electron clouds in coaxial geometries with strong externally applied azimuthal flows and in the presence of a residual neutral gas. For this ...

American Institute of Physics (AIP)2023

Exploration of the parameter space for the excitation and saturation of Edge Harmonic Oscillations

Guillermo Bustos Ramirez

This thesis presents advancements in the understanding of the plasma conditions leading to the excitation and saturation of the Edge Harmonic Oscillations (EHOs) observed during QH-mode operation in tokamak plasmas. Such operations represent a safer altern ...

EPFL2023

The hunt for the Karman 'constant' revisited

Peter Monkewitz

The log law of the wall, joining the inner, near-wall mean velocity profile (MVP) in wall-bounded turbulent flows to the outer region, has been a permanent fixture of turbulence research for over hundred years, but there is still no general agreement on th ...

Cambridge University Press2023