Publications related to Magnetic diffusion

Global fluid simulations of plasma turbulence in stellarators

In order to cope with the decarbonization challenge faced by many countries, fusion is one of the few alternatives to fossil fuels for the production of electricity. Two devices invented in the middle of the previous century have emerged as the most promis ...

EPFL2024

An analytical solution of the isentropic vortex problem in the special relativistic magnetohydrodynamics

Junming Duan

The isentropic vortex problem is frequently solved to test the accuracy of numerical methods and verify corresponding code. Unfortunately, its existing solution was derived in the relativistic magnetohydrodynamics by numerically solving an ordinary differe ...

ACADEMIC PRESS INC ELSEVIER SCIENCE2022

A non-twisting flux tube for local gyrokinetic simulations

Stephan Brunner, Justin Richard Ball

Local gyrokinetic simulations use a field-aligned domain that twists due to the magnetic shear of the background magnetic equilibrium. However, if the magnetic shear is strong and/or the domain is long, the twist can become so extreme that it fails to prop ...

2021

Effect of the tangential NBI current drive on the stability of pressure and energetic particle driven MHD modes in LHD plasma

Wilfred Anthony Cooper, Joao Varela

The aim of the present study is to analyze the stability of the pressure gradient driven modes (PM) and Alfven eigenmodes (AE) in the large helical device (LHD) plasma if the rotational transform profile is modified by the current drive of the tangential n ...

IOP Publishing Ltd2020

First demonstration of real-time kinetic equilibrium reconstruction on TCV by coupling LIUQE and RAPTOR

Olivier Sauter, Jean-Marc Moret, Federico Alberto Alfredo Felici, Antoine Pierre Emmanuel Alexis Merle, Cristian Galperti, Francesco Carpanese

Kinetic equilibrium reconstruction (KER) in tokamaks is the solution of the free-boundary MHD equilibrium that best fits the external magnetic measurements and the internal plasma profiles as imposed from modeling and/or available internal measurements. In ...

IOP Publishing Ltd2020

Runaway electron synchrotron radiation in a vertically translated plasma

Basil Duval, Joan Decker, Umar Sheikh, Artur Perek, Gergely Papp

Synchrotron radiation observed from runaway electrons (REs) in tokamaks depends upon the position and size of the RE beam, the RE energy and pitch distributions, as well as the location of the observer. We show experimental synchrotron images of a vertical ...

IOP Publishing Ltd2020

Non-linear modelling of saturated internal and external MHD instabilities in tokamaks

Andreas Kleiner

Macroscopic instabilities and their unfavourable effects on plasma confinement pose a central challenge for the development of reactor relevant tokamak scenarios. Some promising operation scenarios feature extended regions of low magnetic shear. These are ...

EPFL2019

Isotope identity experiments in JET-ILW with H and D L-mode plasmas

Henri Weisen

NBI-heated L-mode plasmas have been obtained in JET with the Be/W ITER-like wall (JET-ILW) in H and D, with matched profiles of the dimensionless plasma parameters, rho*, nu*, beta and q in the plasma core confinement region and same T-i/T-e and Z(eff). Th ...

IOP Publishing Ltd2019

Projective multiscale time-integration for electrostatic particle-in-cell methods

Jan Sickmann Hesthaven, Paul Isaac Denis Louis Marie Cazeaux

The simulation of problems in kinetic plasma physics is often challenging due to strongly coupled phenomena across multiple scales. In this work, we propose a wavelet-based coarse-grained numerical scheme, based on the framework of Equation-Free Projective ...

2019

Neoclassical tearing mode seeding by coupling with infernal modes in low-shear tokamaks

Jonathan Graves, Wilfred Anthony Cooper, Federico David Halpern, Daniele Brunetti, Andreas Kleiner

A numerical and an analytical study of the triggering of resistive MHD modes in tokamak plasmas with low magnetic shear core is presented. Flat q profiles give rise to fast growing pressure driven MHD modes, such as infernal modes. It has been shown that i ...

IOP Publishing Ltd2016

Guiding-centre transformation of the radiation-reaction force in a non-uniform magnetic field

Joan Decker

In this paper, we present the guiding-centre transformation of the radiation reaction force of a classical point charge travelling in a non-uniform magnetic field. The transformation is valid as long as the gyroradius of the charged particles is much small ...

Cambridge University Press2015

Extended MHD simulations of infernal mode dynamics and coupling to tearing modes

Jonathan Graves, Wilfred Anthony Cooper, Federico David Halpern, Daniele Brunetti

A numerical study of pressure driven magnetohydrodynamic (MHD) instabilities in a low-shear tight aspect ratio configuration is presented. When the magnetic shear is sufficiently small over an extended region in the core, enhanced instability occurs due to ...

Iop Publishing Ltd2015

Stability of Tokamak and RFP Plasmas with an Extended Region of Low Magnetic Shear

Daniele Brunetti

It has been observed experimentally that magnetically confined plasmas, characterised by the safety factor q with a small or slightly inverted magnetic shear, have good confinement properties. Such plasmas typically have no internal transport barrier, oper ...

EPFL2015

ADX: a high field, high power density, advanced divertor and RF tokamak

Christian Gabriel Theiler, Francesca Maria Poli, Yu Lin, John Wilson

The MIT Plasma Science and Fusion Center and collaborators are proposing a high-performance Advanced Divertor and RF tokamak eXperiment (ADX)-a tokamak specifically designed to address critical gaps in the world fusion research programme on the pathway to ...

IOP Publishing Ltd2015

Three-dimensional distortions of the tokamak plasma boundary: boundary displacements in the presence of saturated MHD instabilities

Jonathan Graves, Wilfred Anthony Cooper, Daniele Brunetti

The three-dimensional plasma boundary displacement induced by long-lasting core magnetohydrodynamic (MHD) instabilities has been measured in JET, MAST and NSTX. Only saturated instabilities are considered here since transient rapidly growing modes which de ...

IOP Publishing Ltd2014

Analysis of global hydromagnetic instabilities driven by strongly sheared toroidal flows in tokamak plasmas

Jonathan Graves

Recent numerical calculations have shown that while strong toroidal rotation can increase the external kink limit of tokamak plasmas, the associated rotation shear can drive a Kelvin-Helmholtz like global instability in the plasma, if the rotation frequenc ...

Iop Publishing Ltd2013

Sampling and reconstructing diffusion fields in presence of aliasing

Martin Vetterli, Juri Ranieri

The reconstruction of a diffusion field, such as temperature, from samples collected by a sensor network is a classical inverse problem and it is known to be ill-conditioned. Previous work considered source models, such as sparse sources, to regularize the ...

2013

Turbulent regimes in the tokamak scrape-off layer

Paolo Ricci, Joaquim Loizu Cisquella, Sébastien Jolliet, Federico David Halpern, Annamaria Mosetto

We identify the turbulent regimes in the tokamak scrape-off layer as a function of plasma resistivity, electron to ion mass ratio, safety factor, and magnetic shear. We find that two main instabilities drive turbulence in the SOL: Drift Waves, with their r ...

2013

Ideal ballooning modes in the tokamak scrape-off layer

Paolo Ricci, Joaquim Loizu Cisquella, Sébastien Jolliet, Federico David Halpern, Annamaria Mosetto

A drift-reduced Braginskii fluid model is used to carry out a linear and non-linear study of ideal ballooning modes in the tokamak scrape-off layer. First, it is shown that the scrape-off layer finite connection length and boundary conditions modify the id ...

American Institute of Physics2013

Superparamagnetic anisotropic elastomer connectors exhibiting reversible magneto-piezoresistivity

Thomas Maeder

An anisotropic magnetorheological composite formed by dispersions of silver-covered magnetite microparticles (Fe3O4@Ag) in polydimethylsiloxane (PDMS) displaying electrical conduction only in one preferred direction is presented. A set-up for applying and ...

Elsevier2013