Publications by Ivo Furno | EPFL Graph Search

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Basic aspects of suprathermal ion transport in interchange-mode unstable plasmas are investigated in the simple toroidal plasma device TORPEX. Suprathermal ions are generated with a miniaturized lithium 6+ ion source with energies up to 1keV, and are detected using a double-gridded energy analyzer mounted on a two-dimensional movable system in the poloidal cross-section. The signal-to-noise ratio is enhanced by applying a modulated biasing voltage to the suprathermal ion source and using a synchronous detec

In burning plasmas, fast ions may be generated by ion cyclotron resonance heating, neutral beam injection and fusion reactions. Fast ions will be responsible for a significant fraction of plasma heating and, in some scenarios, non-inductive current drive. Fast ions are also present in natural plasmas, such as the solar corona or the magnetosphere, where they are presumably accelerated by wave-particle interactions. The high temperatures of tokamak plasmas and the huge spatial scale of astrophysical plasmas

A large area antenna generates a plasma by both inductive and capacitive coupling; it is an electromagnetically coupled plasma source. In this work, experiments on a large area planar RF antenna source are interpreted in terms of a multi-conductor transmis ...

In view of controlling wall and divertor heat loads in magnetic fusion devices, we investigate the possibility of creating convective cells by means of biased electrodes for turbulence and blob control in the simple magnetized toroidal plasmas of TORPEX. A two-dimensional array of 24 electrodes is installed on a metal limiter to test different biasing schemes. This allows influencing significantly the frequency of the dominant mode as well as radial and vertical velocities of blobs. Detailed measurements al

Surface dielectric barrier discharge performance deteriorates in humid air, with permanent and/or reversible degradation of its components. Plasma operation in a humid environment is unavoidable when humid air or water-containing materials are treated. Exp ...

We report on recent experimental, numerical and theoretical investigations of suprathermal ion transport and turbulent plasma dynamics in TORPEX. TORPEX is a toroidal device in which field-aligned blobs are intermittently generated and propagate across a c ...

Simulations of edge turbulence are particularly challenging due to the presence of large amplitude fluctuations and to the coupling of equilibrium and fluctuating scales. While validating edge simulations is necessary to assess the accuracy of our understanding, difficulties in experimental diagnostics and the lack of a precise validation methodology have, to date, severely limited the process. The Global Braginskii Solver (GBS) code has been developed to simulate plasma turbulence in edge-relevant conditio

Plasma-activated water (PAW) is increasingly recognized for its bactericidal properties. To advance this technology toward practical applications and deepen the understanding of its mechanisms, it is crucial to study the storage stability of PAW, focusing ...

We present applications of a recently developed method, the singular value decomposition inversion (SVD-I), for inverting line integrated multichannel interferometer measurements in fusion devices. The method expands the local electron density profiles into a limited series of orthogonal basis functions formed from the singular value decomposition of Thomson scattering measurements, which are obtained at much lower frequencies than the interferometer data. Because these basis functions are formed from a loc

Three-dimensional and two-dimensional seeded blob simulations are performed with five different fluid models, all based on the drift-reduced Braginskii equations, and the numerical results are compared among themselves and validated against experimental me ...

Intermittent phenomena have long been studied in the context of nondiffusive transport across a variety of fields. In the TORPEX device, the cross-field spreading of an injected suprathermal ion beam by electrostatic plasma turbulence can access different ...

Different types of central relaxation oscillations are observed in the presence of ECH depending on the location of the deposited power. In the TCV tokamak, normal sawteeth, i.e. triangular sawteeth similar to ohmic sawteeth, and saturated sawteeth are observed with central ECH power deposition, while giant sawteeth and 'humpback' oscillations occur when heating close to the sawtooth inversion surface of the local soft X ray emissivity. New measurements with high temporal resolution show that the crash phas

A helicon-based plasma source is under development and exploration at CEA-IRFM to produce an efficient and dense magnetized plasma column. The final objective of this development is the extraction and acceleration of a blade-like negative ion beam in view ...

Confinement in TCV electron cyclotron heated discharges was studied as a function of plasma shape, i.e. as a function of elongation, 1.1 < kappa < 2.15, and triangularity, -0.65 less than or equal to delta less than or equal to 0.55. The electron energy confinement time was found to increase with elongation, owing in part to the increase of plasma current with elongation. The beneficial effect of negative triangularities was most effective at low power and tended to decrease at the higher powers used. The l

Electrostatic turbulence, related structures and their effect on particle, heat and toroidal momentum transport are investigated in TORPEX simple magnetized plasmas using high-resolution diagnostics, control parameters, linear fluid models and nonlinear nu ...

A unique parabolic relation is observed to link skewness and kurtosis of around ten thousand density fluctuation signals, measured over the whole cross section of a toroidal magnetized plasma for a broad range of experimental conditions. All the probabilit ...

We present a recent upgrade of the incoherent Thomson scattering (TS) diagnostic for the Resonant Antenna Ion Device (RAID), a linear plasma source based on helicon excitation operated at the Swiss Plasma Center at Ecole Polytechnique Fédérale de Lausanne. By operating in the visible range, which facilitates the recording of the spectrally resolved TS signal with a gated camera, this system has greatly enhanced the ability to characterize the plasmas generated by RAID in argon, helium, deuterium, and hydrog

The design and first results are presented from a bolometric diagnostic with high temporal resolution recently installed on the TCV tokamak. The system consists of two pinhole cameras viewing the plasma from above and below at the same toroidal location. Each camera is equipped with an AXUV-16ELO linear array of 16 p-n junction photodiodes, characterized by a flat spectral sensitivity from ultraviolet to x-ray energies, a high temporal response (< 0.5 mu s), and insensitivity to low-energy neutral particles

Owing to its detailed diagnostics, feasibility of parameter scans, and relatively simple configuration, the basic plasma physics experiment TORPEX is an ideal testbed in which to perform experiment/simulation comparisons and to contribute to the establishment of the validation methodology. Focusing on observables related to Langmuir probe measurements, we consider a number of physical quantities that can be used as observables for experiment/simulation comparison. We classify the observables according to a

A new definition of the sheath edge is rigorously derived taking into account the kinetic properties of the plasma, and a consistent set of local sheath edge conditions is presented for the case of a magnetic field perpendicular to the wall. These local boundary conditions give explicit expressions for the ion velocity, the electron velocity, and the electron heat flux at the sheath edge, which can be easily implemented in a fluid code. It is shown that in the case of positive current to the wall, the commo

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Investigation of suprathermal ion transport in TORPEX

Investigation of suprathermal ion transport in TORPEX

Electromagnetic, complex image model of a large area RF resonant antenna as inductive plasma source

Convective cells and blob control in a simple magnetized torus

Surface DBD degradation in humid air, and a hybrid surface-volume DBD for robust plasma operation at high humidity

Non-diffusive transport of suprathermal ions by intermittent turbulent structures

Progressive steps towards global validated simulation of edge plasma turbulence

Plasma-activated water retains antimicrobial properties against Escherichia coli after 72 h of storage

Application of the singular value decomposition method for inversion of interferometer measurements in fusion plasmas

Blob dynamics in the TORPEX experiment: a multi-code validation

Time intermittency in nondiffusive transport regimes of suprathermal ions in turbulent plasmas

Understanding sawtooth activity during intense electron cyclotron heating experiments on TCV

Magnetic field configurational study on a helicon-based plasma source for future neutral beam systems

Energy confinement and MHD activity in shaped TCV plasmas with localized electron cyclotron heating

Electrostatic instabilities, turbulence and fast ion interactions in the TORPEX device

Universal statistical properties of drift-interchange turbulence in TORPEX plasmas

High resolution incoherent Thomson scattering diagnostic for the Resonant Antenna Ion Device (RAID) helicon plasmas

Fast bolometric measurements on the TCV tokamak

The validation project on the TORPEX basic plasma physics experiment

Sheath boundary conditions for plasma fluid models