Solutions for thermally mismatched brazing operations for ceramic tokamak magnetic sensor

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The first observations of ion cyclotron emission (ICE) in the TCV tokamak are reported. The measured ICE frequency closely follows the deuterium ion cyclotron frequency at the magnetic axis, with temporal variations consistent with equilibrium evolution and associated shifts of the magnetic axis. Core ICE is observed primarily during phases with combined electron cyclotron resonance heating (ECRH) and neutral beam injection (NBI). In most discharges the second harmonic dominates, while in others higher harm

The Fast Ion Loss Detector (FILD), installed on TCV in 2020 was redesigned and upgraded several times throughout this PhD. The collimator apertures were reduced to increase the energy resolution, a faster CMOS camera was intalled, a novel fast camera (up to 4 MHz) was installed to access microsecond velocity-space mapping, two more slits were added on the bottom partof the FILD head accessing to all magnetic field configurations, a bandpass optical filter was installed to reduce residual light contamination

Edge plasma behaviour plays a central role in determining the overall confinement and operational limits of tokamak plasmas. In particular, turbulence at the plasma boundary strongly influences particle and heat transport and remains a key target for performance optimization. Among the shaping strategies currently explored, negative triangularity (NT) operation has emerged as a viable alternative to conventional positive triangularity (PT) plasmas, having demonstrated improved confinement, reduced turbulenc

The Wendelstein 7-X (W7-X) stellarator has completed two consecutive experimental campaigns OP 2.2 (Sep.-Dec. 2024) and OP 2.3 (Feb.-May 2025) under a new operational strategy enabling more than one year of uninterrupted device availability. This approach, supported by exceptionally high subsystem reliability, allowed sustained high-efficiency plasma operations with up to 80–100 discharges per day across a broad range of magnetic configurations. Several key technical upgrades-most notably the first operatio

The Divertor Tokamak Test (DTT) facility will be equipped with one of the largest ECRH systems envisaged for fusion research. The system is organized in 4 clusters, each one composed of 8 gyrotrons fed in pairs by four main high voltage power supplies (MHVPS), with gyrotrons and MHVPS arranged on two separate floors of a new dedicated building. Since gyrotron specifications are similar to those of ITER, a joint procurement procedure was made between Fusion for Energy and DTT. The first DTT pre-series gyrotr

Increased focus has been recently given to the ion temperature Ti near the separatrix and in the scrape-off layer (SOL) due to its impact on plasma confinement, wall sputtering, heat fluxes, and edge turbulence. In current tokamaks, high pedestal collisionality often clamps pedestal top ion and electron temperatures together. However, thermal decoupling occurs in the SOL due to the different ion and electron masses, leading to T-i/T-e>1 at the separatrix and in the SOL. Despite consistently observing elevat

Electrochemical CO2 reduction will be a key player in net-zero technologies, yet its industrial implementation is limited. Improvements by fine-tuning the microenvironments, electrolyte environments around the catalytic sites, have been scarce due to the interplay between electrode kinetics and transport. Here, we couple atomistic insights with continuum transport via ab-initio multiscale modeling, explicitly including electrolyte effects at all scales. The model was validated on Ag planar electrodes in sev

We present the results of 3D, flux-driven, global, two-fluid electrostatic turbulence simulations in a 5-field period stellarator with an island divertor. The numerical simulations are carried out with the GBS code, which solves the two-fluid drift-reduced Braginskii equations and has been extended recently to simulate plasma turbulence in non-axisymmetric magnetic equilibria. The vacuum magnetic field used in the simulations is carefully constructed using Dommaschk potentials in order to describe a configu

The audiovisual communications laboratory (lcav.epfl.ch) is looking for students for the development of an interferential hyperspectral camera, as part of a semester project. It involves building, testing and improving, in collaboration with the scientific and technical team, a portable prototype based on a principle already successfully tested on an optical table. The ideal candidates would be trained in mechanics, electronics, embedded systems or optics.

In DEMO reactor to produce electricity, a total installed power up to 150 MW is considered. In the heating mix, neutral beam (NB) injectors of high neutral particle energy (0.8-1 MeV) with high wall-plug efficiency (η in the range of 50% to 60%) will be required. Present design considered a NB system delivering in total 50 MW. In the Siphore NB concept [1], one of the promising candidates to meet these challenging requirements, negative ions will be extracted from a long, thin ion source 3 m high and 15 cm

A recent multi-machine experimental campaign initiated by the ITER Organization concluded that inner-wall limited (IWL) plasmas have a near scrape-off layer (SOL) heat-flux decay length of a few mm's, while the far SOL can have a width of several cm's. The ITER inner-wall design was revised last year in order to accommodate for the effects of this narrow feature. In the present talk, we address the physics behind the development of the narrow heat-flux feature in the near SOL of IWL discharges. Our investig

In the tokamak scrape-off layer (SOL) the magnetic field lines are open, channeling particles and heat onto plasma facing components, and constraining their lifetime. Therefore, safe operation of future fusion reactors requires an understanding of SOL plasma dynamics. Recently, we have gained deep insights into the tokamak SOL dynamics by means of massively-parallel fluid electromagnetic turbulence simulations carried out with the Global Braginskii Solver (GBS) code. GBS is currently capable of performing f

Background. The small characteristic sizes (in the range of 102 - 103 μm) of Microstructured reactors (MSR) lead to very high specific interfacial area which, in turn, increases heat- and mass transfer efficiency. However, for quasi instantaneous exothermic reactions, the overall reaction kinetics in MSR is strongly influenced by mixing. The characteristic time of the latter phenomenon varies from millisecond to seconds depending on the operating conditions used. If mixing is the rate determining step for h

The increasing quality and durability of Solid Oxide Fuel Cells (SOFC) state-of-the-art materials renders the long-term testing of fuel cells difficult since considerably long equipment times are needed to obtain valuable results. Moreover, reproducibility issues are common due to the high sensitivity of the performance and degradation on the testing conditions. An original segmented cell configuration has been adopted in order to carry out four tests in parallel, thus decreasing the total experimental time

Based on results from a field survey campaign, this paper describes three new developments which have been integrated to provide for a comprehensive basis l'or the evaluation of overheating risk in offices. Firstly, a set of logistic regression equations have been derived to predict the probability of office occupants' adaptation of personal and environmental characteristics. Secondly, empirical adaptive increments (offsets in comfort temperature) have been derived for each of these modes of adaptation. Thi

Metal matrix composites are known for their excellent specific mechanical properties. Nevertheless, because of the thermal expansion mismatch between the matrix and the reinforcements, thermal stresses arise at the interfaces of such materials. In order to relax these stresses, dislocations are emitted from the interface and propagate in the matrix, which can influence the mechanical behavior of the composite material. Mechanical spectroscopy, which characterizes the ability of a solid to dissipate energy u

The peakedness of the density profile in source-free MHD-quiescent L-mode plasmas with lower hybrid current drive is observed to decrease with decreasing peaking of the current profile. For the discharges investigated, which include normal and reversed magnetic shear plasmas, the relationship can be summarized as n(e0)/ congruent to 1.2l(i), where l(i) is the normalized internal inductance. Density profiles are monotonically peaked at negative shear. Since density profiles remain peaked at zero loop v

Stress-induced changes in the imprint and switching behavior of (111)-oriented Pb(Zr,Ti)O-3 (PZT)-based capacitors have been studied using piezoresponse force microscopy. Visualization of polarization distribution and d(33)-loop measurements in individual 1x1.5-mum(2) capacitors before and after stress application, generated by substrate bending, provided direct experimental evidence of stress-induced switching. Mechanical stress caused elastic switching in capacitors with the direction of the resulting pol

Experiments on the TCV tokamak have shown that rapid vertical movement of diverted ELMy H-mode plasmas can affect the time sequence of edge localized modes. The effect is attributed to the induction of an edge current during the movement of the plasma column in the spatially inhomogeneous vacuum field of a single-null configuration. In TCV the fast vertical movement is provoked by the positional control coils inside the vacuum vessel, however it is argued that a similar effect might be produced in larger de

There is currently both considerable interest in the physics of ELM transport in the scrape-off layer (SOL) and concern over the impact of the ELM power and particle loads on the divertor targets of future fusion reactors. This paper describes some experimental observations of the reaction of target floating potentials and currents during ELMS in TCV, relying principally on fast measurements of these parameters using tile embedded Langmuir probe arrays. Clear evidence is presented for rapid modifications in

Solutions for thermally mismatched brazing operations for ceramic tokamak magnetic sensor

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First observations of ion cyclotron emission in the TCV tokamak

Study of the fast-ion confinement via velocity-space resolved measurements in several plasma scenarios in the TCV tokamak

Thermal helium beam measurements of plasma edge turbulence in positive and negative triangularity plasmas on TCV

Overview of Wendelstein 7-X high-performance operation

First RF operations of the gyrotron for the DTT ECRH System

Separatrix Ion to Electron Temperature Ratio in the Tcv and Asdex Upgrade Tokamaks

Microenvironment effects from first principles multiscale modeling of electrochemical CO2 reduction

First global simulations of plasma turbulence in a stellarator with an island divertor

Development of a hyperspectral camera

A novel helicon plasma source for negative ion beams for fusion

Turbulence simulations of the narrow heat-flux feature in inner-wall limited tokamaks

Plasma turbulence simulations of the tokamak scrape-off layer

Effect of hot spots in microstructured reactors on product distribution during quasi-instantaneous exothermic reactions

Segmented cell testing for cathode parameter investigation

An integrated adaptive model for overheating risk prediction

Spectroscopie mécanique de la relaxation des contraintes d'interface dans les composites à matrice métallique

Shear and collisionality dependences of particle pinch in JET L-mode plasmas

Mechanical stress effect on imprint behavior of integrated ferroelectric capacitors

Magnetic triggering of ELMs in TCV

ELM driven divertor target currents on TCV