Publications by Matteo Vallar | EPFL Graph Search

First Microsecond Velocity-space Resolved Simultaneous Measurements of Co- and Counter-current Fast-ion Losses in Forward and Reverse Magnetic Field in a Tokamak

Basil Duval, Ambrogio Fasoli, Pierre Lavanchy, Alexander Karpushov, Yanis Andrebe, Matthieu Toussaint, Matteo Vallar, Jesús Poley Sanjuán

A novel Fast Ion Loss Detector was designed, manufactured, installed and commissioned at the Tokamak & aacute; Configuration Variable. This is the first Fast Ion Loss Detector to feature four collimators that enable simultaneous detection of co- and counte ...

IOP Publishing Ltd2025

Electromagnetic instability and turbulence in plasmas with positive and negative triangularity

Olivier Sauter, Justin Richard Ball, Matteo Vallar, Reinart Andreas J. Coosemans

While a number of studies exist comparing positive triangularity (PT) and negative triangularity (NT) δ, the nature of how the normalized electron pressure β affects microinstabilities and turbulence in fusion devices with substantial δ has not been studie ...

AIP Publishing2025

Design and upgrades of the TCV fast ion loss detector

Basil Duval, Ambrogio Fasoli, Pierre Lavanchy, Alexander Karpushov, Yanis Andrebe, Augustin Charles Roger Philippe Clément, Matteo Vallar, Jesús Poley Sanjuán

The Tokamak à Configuration Variable has a unique Fast Ion Loss Detector (FILD) that allows the simultaneous measurement of co- and counter-current fast-ion losses in forward or reverse magnetic field. Recently, multiple novel upgrades have been implemente ...

AIP Publishing2025

Progress in the development of the ITER baseline scenario in TCV

Olivier Sauter, Stefano Coda, Alexander Karpushov, Yann Camenen, Benoît Labit, Antoine Pierre Emmanuel Alexis Merle, Olivier Claude Martin Février, Simon Van Mulders, Filippo Bagnato, Alessandro Pau, Matteo Vallar, Cassandre Ekta Contré, Stefano Marchioni, Oleg Krutkin, Reinart Andreas J. Coosemans

Under the auspices of EUROfusion, the ITER baseline (IBL) scenario has been jointly investigated on AUG and TCV in the past years and this paper reports on the developments on TCV. It is found that the performance of TCV IBL is mainly limited by (neoclassi ...

2024

Experiments and gyrokinetic simulations of TCV plasmas with negative triangularity in view of DTT operations

Olivier Sauter, Stefano Coda, Alberto Mariani, Justin Richard Ball, Filippo Bagnato, Matteo Vallar

Negative triangularity (NT) scenarios in TCV have been compared to positive triangularity (PT) scenarios using the same plasma shapes foreseen for divertor tokamak test tokamak operations. The experiments provided a NT/PT L-mode pair and a PT H-mode with d ...

Iop Publishing Ltd2024

Overview of physics results from MAST upgrade towards core-pedestal-exhaust integration

Olivier Sauter, Holger Reimerdes, Christian Gabriel Theiler, Federico Alberto Alfredo Felici, Matteo Vallar, Samuele Mazzi

Recent results from MAST Upgrade are presented, emphasising understanding the capabilities of this new device and deepening understanding of key physics issues for the operation of ITER and the design of future fusion power plants. The impact of MHD instab ...

IOP Publishing Ltd2024

Overview of fast particle experiments in the first MAST Upgrade experimental campaigns

Matteo Vallar

MAST-U is equipped with on-axis and off-axis neutral beam injectors (NBI), and these external sources of super-Alfv & eacute;nic deuterium fast-ions provide opportunities for studying a wide range of phenomena relevant to the physics of alpha-particles in ...

IOP Publishing Ltd2024

Experimental research on the TCV tokamak

Patrick Blanchard, Stefano Alberti, Ambrogio Fasoli, Timothy Goodman, Yves Martin, Olivier Sauter, Henri Weisen, Ivo Furno, Holger Reimerdes, Jean-Philippe Hogge, Stefano Coda, Alexander Karpushov, Yanis Andrebe, Duccio Testa, Benoît Labit, Christian Gabriel Theiler, Federico Alberto Alfredo Felici, Jérémy Genoud, Hugo De Oliveira, Antoine Pierre Emmanuel Alexis Merle, Antoine Baillod, Joan Decker, Cedric Kar-Wai Tsui, Pedro Andres Molina Cabrera, Umar Sheikh, Cristian Galperti, Marcelo Baquero Ruiz, Aylwin Iantchenko, Mengdi Kong, Francesco Carpanese, Federico Pesamosca, Olivier Claude Martin Février, Simon Van Mulders, Nicola Offeddu, Garance Hélène Salomé Durr-Legoupil-Nicoud, Maurizio Giacomin, Filippo Bagnato, Davide Galassi, Arsène Stéphane Tema Biwole, Lorenzo Martinelli, , , , , , , , , , , , , , , , , , , , , , , ,

Overview of the EUROfusion Tokamak Exploitation programme in support of ITER and DEMO

Patrick Blanchard, Basil Duval, Timothy Goodman, Jean-Marc Moret, Olivier Sauter, Henri Weisen, Holger Reimerdes, Stefano Coda, Alexander Karpushov, Duccio Testa, Benoît Labit, Christian Gabriel Theiler, Federico Alberto Alfredo Felici, Antoine Pierre Emmanuel Alexis Merle, Joan Decker, Cedric Kar-Wai Tsui, Umar Sheikh, Cristian Galperti, Marcelo Baquero Ruiz, Aylwin Iantchenko, Mengdi Kong, Olivier Claude Martin Février, Paulo Giovane Paschoali Pereira Puglia, Simon Van Mulders, Nicola Offeddu, Garance Hélène Salomé Durr-Legoupil-Nicoud, Filippo Bagnato, Davide Galassi, Lorenzo Martinelli, Jean Arthur Cazabonne, Alessandro Pau, Matteo Vallar, Sophie Danielle Angelica Gorno, Claudia Colandrea, Dmytry Mykytchuk, Gino Marceca, Davide Mancini, Cassandre Ekta Contré, Guang-Yu Sun, , , , , , , , , ,

Negative triangularity scenarios: from TCV and AUG experiments to DTT predictions

Olivier Sauter, Stefano Coda, Justin Richard Ball, Filippo Bagnato, Matteo Vallar

Experiments, gyrokinetic simulations and transport predictions were performed to investigate if a negative triangularity (NT) L-mode option for the Divertor Tokamak Test (DTT) full-power scenario would perform similarly to the positive triangularity (PT) H ...

IOP Publishing Ltd2024

Overview of T and D-T results in JET with ITER-like wall

Olivier Sauter, Holger Reimerdes, Duccio Testa, Benoît Labit, Umar Sheikh, Olivier Claude Martin Février, Eduardo José Lascas Neto, Cristian Sommariva, Alessandro Pau, Matteo Vallar, Gino Marceca, Cassandre Ekta Contré, Mackenzie Peter-Fulford Van Rossem, Samuele Mazzi

In 2021 JET exploited its unique capabilities to operate with T and D-T fuel with an ITER-like Be/W wall (JET-ILW). This second major JET D-T campaign (DTE2), after DTE1 in 1997, represented the culmination of a series of JET enhancements-new fusion diagno ...

IOP Publishing Ltd2024

Evaluation of neutron dose rates at the TCV tokamak facility

Patrick Blanchard, Henri Weisen, Matteo Vallar

A detailed MCNP neutronics model of the building housing the TCV tokamak has been developed. Predicted dose rates have been compared to neutron dose measurements at 12 locations in the building obtained during neutral beam injection into TCV plasmas. This ...

2023

TCV Tokamak Neutron Shielding Upgrade for Dual NBI Operation

Patrick Blanchard, Basil Duval, Henri Weisen, Alexander Karpushov, Duccio Testa, Jérémie Dubray, Antoine Pierre Emmanuel Alexis Merle, Matteo Vallar

The Tokamak a Configuration variable (TCV) is equipped with two neutral beam injection (NBI) systems delivering up to 1.2 MW each for pulse durations of up to 2 s. The first system (NBI1), designed for an injection energy in the range of 25 to 30 keV has b ...

2023

Interaction of high-energy neutral beams with Divertor Tokamak Test plasma

Matteo Vallar

The Divertor Tokamak Test (DTT) is a new, super-conducting device, being constructed in Frascati, Italy. DTT will be capable of plasma operations at high density and high heating power, in conditions relevant to address the power exhaust issue in support o ...

2023

Predictive modeling of Alfvén eigenmode stability in inductive scenarios in JT-60SA

Javier García Hernández, Antonio José Pereira de Figueiredo, Matteo Vallar

The JT-60SA device offers unique conditions before ITER for the study of the interaction of energetic particles with plasma waves. With similar dimensions to JET, e.g., a major radius but with a slightly more elongated plasma volume, JT-60SA is used as a h ...

Frontiers Media Sa2023

Excitation of toroidal Alfvén eigenmodes with counter-current NBI in the TCV tokamak

Alexander Karpushov, Laurie Porte, Matteo Vallar, Samuele Mazzi

In TCV, unstable modes excited by resonant interaction between the shear Alfvèn waves in con- tinuum gaps and energetic particles have been observed in scenarios with Neutral Beam Injection (NBI). TCV is a middle-size device (R 0 /a = 0.88/0.25) equipped w ...

IOP Publishing Ltd2023

Study of fast-ion-driven toroidal Alfvén eigenmodes impacting on the global confinement in TCV L-mode plasmas

Stephan Brunner, Laurent Villard, Stefano Coda, Javier García Hernández, Aylwin Iantchenko, Justin Richard Ball, Matteo Vallar, Umesh Kumar, Oleg Krutkin, Luke Simons, Jesús Poley Sanjuán, Samuele Mazzi, Baruch Rofman

Following recent observations of unstable Toroidal Alfven Eigenmodes (TAEs) in a counter-current Neutral Beam Injection (NBI) scenario developed in TCV, an in-depth analysis of the impact of such modes on the global confinement and performance is carried o ...

2023

Simulating energetic particle losses in JET plasmas with a reverse integration biasing scheme

Mario Ludovico Podesta, Matteo Vallar

An integrated energetic particle transport model has been constructed in JET plasmas constrained by experimental fast ion loss measurements. The model incorporates a synthetic fast ion loss detector identical to JET's thin-foil Faraday cup fast ion loss de ...

IOP Publishing Ltd2022

Enhanced confinement in diverted negative-triangularity L-mode plasmas in TCV

Olivier Sauter, Stefano Coda, Laurie Porte, Benoît Labit, Alessandro Marinoni, Antoine Pierre Emmanuel Alexis Merle, Leonardo Pigatto, Cedric Kar-Wai Tsui, Umar Sheikh, Filippo Bagnato, Alessandro Pau, Matteo Vallar

The favorable confinement properties of negative-triangularity (NT) tokamak configurations were discovered in the TCV tokamak in the late 1990s and were documented over the two following decades, through investigations of predominantly electron-heated plas ...

2022

Numerical studies on saturated kink and sawtooth induced fast ion transport in JET ITER-like plasmas

Mario Ludovico Podesta, Matteo Vallar

This presentation examines the energetic particle transport induced by saturated kink modes and sawtooth crashes in JET deuterium plasmas. It is known that kink mode-resonant transport and phase-space redistribution from sawtooth crashes can drive strong f ...

IOP Publishing Ltd2022