Publications related to Novel linear analysis for a gyrotron oscillator based on a spectral approach

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

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 ...

Bristol2023

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, Jérémy Genoud, Francesco Romano, Ioannis Pagonakis

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 ...

2023

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 UNIV PRESS2023

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

Linear and nonlinear excitation of TAE modes by external electromagnetic perturbations using ORB5

Laurent Villard, Emmanuel Lanti, Alberto Bottino, Mohsen Sadr

The excitation of toroidicity-induced Alfven eigenmodes (TAEs) using prescribed external electromagnetic perturbations (hereafter 'antenna') acting on a confined toroidal plasma, as well as its nonlinear couplings to other modes in the system, is studied. ...

IOP Publishing Ltd2022

Spectral analysis for transmission eigenvalue problems with and without the complementing conditions

Jean Louis-Alexandre Fornerod

The interior transmission eigenvalue problem is a system of partial differential equations equipped with Cauchy data on the boundary: the transmission conditions. This problem appears in the inverse scattering theory for inhomogeneous media when, for some ...

EPFL2022

Prototype mitre bends of the ex-vessel waveguide system for the ITER upper launcher: Thermal hydraulic simulations and experiments with off-center mm-wave beams

Timothy Goodman, René Chavan, Anastasia Xydou, Matteo Vagnoni, Humberto Torreblanca Quiroz

On ITER, long pulse gyrotrons are required as a power source for electron cyclotron heating (ECH) and current drive (CD). The microwaves are guided from the gyrotrons, which are placed far from the Tokamak, into the plasma by transmission lines (TLs) and a ...

2021

Linear studies of spurious backward-wave instabilities in a dielectric-loaded smooth-wall gyrotron beam ducts

Stefano Alberti, Jean-Philippe Hogge, Jérémy Genoud

Recently developed self-consistent models for beam-wave interaction simulations of a gyrotron oscillator have been extended to study spurious backward-wave instabilities in smooth-wall circular symmetric beam ducts. Starting from a purely metallic case, th ...

IEEE2020

A stability theory beyond the co-rotational setting for critical wave maps blow up

Joachim Krieger, Shuang Miao

We exhibit non-equivariant perturbations of the blowup solutions constructed in [18] for energy critical wave maps into

\mathbb{S}^2

. Our admissible class of perturbations is an open set in some sufficiently smooth topology and vanishes near the light co ...

2020

Novel linear analysis for a gyrotron oscillator based on a spectral approach

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

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

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

The hunt for the Karman 'constant' revisited

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

Linear and nonlinear excitation of TAE modes by external electromagnetic perturbations using ORB5

Spectral analysis for transmission eigenvalue problems with and without the complementing conditions

Prototype mitre bends of the ex-vessel waveguide system for the ITER upper launcher: Thermal hydraulic simulations and experiments with off-center mm-wave beams

Linear studies of spurious backward-wave instabilities in a dielectric-loaded smooth-wall gyrotron beam ducts

A stability theory beyond the co-rotational setting for critical wave maps blow up

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

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

A stability theory beyond the co-rotational setting for critical wave maps blow up

Spectral analysis for transmission eigenvalue problems with and without the complementing conditions

The hunt for the Karman 'constant' revisited

Linear and nonlinear excitation of TAE modes by external electromagnetic perturbations using ORB5

Prototype mitre bends of the ex-vessel waveguide system for the ITER upper launcher: Thermal hydraulic simulations and experiments with off-center mm-wave beams

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

Linear studies of spurious backward-wave instabilities in a dielectric-loaded smooth-wall gyrotron beam ducts

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