Development of a 140 GHz, 1 MW, continuous wave gyrotron for the W7-X stellarator

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The neutral beam injection system is a key part of the TCV machine, which is actively exploited in different experimental campaigns. Development of a new ion-optical system (IOS) for the heating beam with intermediate particle energy (up to ~38 keV) has been performed, having obtained the beam simulation results by the IBSimu code. The validity of IBSimu calculations for the existing design concepts was cross-checked with the experimental data of beam profiles and divergence. The newly developed concept of

Suprathermal ions, i.e. ions with energies exceeding those of the bulk plasma, arise in diverse natural and laboratory plasmas ranging from the solar wind to magnetic confinement fusion (MCF) devices. In tokamaks, they are generated by external heating systems and fusion reactions, and a thorough characterization of their dynamics is crucial for safe operation. In tokamaks, the core plasma is separated from the walls by the last closed flux surface (LCFS), which exhibits a null point (X-point) in the poloid

In this work, we compare physics-based dynamic exhaust models with frequency response measurements (FRMs) of the global particle dynamics in the Tokamak à Configuration Variable (TCV). The aim is to understand and model the experimental in-vessel dynamic response of plasma and neutrals to deuterium gas puff modulations with three models of varying fidelity: a 0D three chamber model (TCM); DIV1D, which models the edge plasma in 1D, and SOLEDGE3X for 2D-axisymmetric modeling. We find that the dynamic behavior

Benign termination, in which magnetohydrodynamic (MHD) instabilities deconfine runaway electrons (REs) following hydrogenic injections, is a promising strategy for mitigating dangerous RE loads after disruptions. Recent experiments on the Joint European Torus (JET) have explored this scenario at higher pre-disruptive plasma currents than are achievable on other devices, revealing challenges in obtaining benign terminations at I p ≥ 2.5 MA. This work analyzes the evolution of these high-current RE beams and

The STEP prototype power plant (SPP) will utilize a double null diverted (DND) plasma topology to manage very high divertor heat fluxes within a compact design. The DND configuration provides advantages for divertor power balancing and H-mode access while it is connected, i.e.,

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is small. Due to vertical instabilities and l

The high confinement regime (H-mode) is considered fundamental for high-performance operation in next-step tokamaks. It is generally characterized by the occurrence of edge localized modes (ELMs), even though several no-ELM and small-ELM regimes have extended their operational space in the past years (Viezzer et al 2023 Nucl. Mater. Energy 34 101308). The control and suppression of these modes is a priority for the development of scenarios with a confinements good enough for the ITER baseline (Sips et al 20

Negative triangularity (NT) plasmas achieve enhanced confinement without edge localized modes nor the need to exceed the L-H heating power threshold. Removing this H-mode accessibility constraint opens a new region of parameter space: scenarios with low external heating power. Using simple zero dimensional power balance and standard empirical scaling laws for confinement, we analyze the impact of external heating on several different reactor-relevant devices (i.e. SPARC, MANTA, ITER and DEMO). We determine

[Neo-classical] Tearing Modes ([N]TMs) control is crucial in high-energy devices like ITER due to the disruptions that may cause potential machine damage. This work presents a real-time [N]TM control strategy for the ITER Plasma Control System (PCS), aiming to predict [N]TMs present and their characteristics, and apply stabilization using Electron Cyclotron Heating (ECH). Key components of the [N]TM control scheme are a predictor with extended co-MRE solver, coupled mode width and frequency dynamics, and a

A Diagnostic Neutral Beam Injector (DNBI) is operated on the TCV Tokamak since 2000. Over the years, the plasma source and the ion optical system have benefited from several upgrades, whereas the power supply system remained almost unchanged. DNBI operation is now compromised by the obsolescence of both the power components and the control infrastructure. To allow for a long term reliable operation, a complete renew of the power supplies set is ongoing. It includes a high-speed current source rated 500 A/10

In this work, we study the interplay between triangularity and micro-tearing turbulence using linear and nonlinear flux tube GENE simulations. We consider scenarios with negative and positive triangularity plasma shaping taken from existing tokamaks (TCV, DIII-D, MAST-U and SMART) and EU-DEMO. The study of all these tokamaks reveals a coherent picture. Negative triangularity geometry is more susceptible to micro-tearing modes (MTM), which, when present, make transport much worse than in positive triangulari

This paper describes the speaker diarization systems developed for the Second DIHARD Speech Diarization Challenge (DIHARD II) by the Speed team. Besides describing the system, which considerably outperformed the challenge baselines, we also focus on the lessons learned from numerous approaches that we tried for single and multi-channel systems. We present several components of our diarization system, including categorization of domains, speech enhancement, speech activity detection, speaker embeddings, clus

The electron cyclotron (EC) heating and current drive (H&CD) system developed for the ITER is made of 12 sets of high-voltage power supplies feeding 24 gyrotrons connected through 24 transmission lines (TL), to five launchers, four located in upper ports a ...

Understanding the turbulent dynamics of the tokamak scrape-off layer (SOL) is critical for the safe operation of future fusion reactors. In this region of the tokamak device, the plasma exhausts particles and heat onto plasma facing hardware components, which may limit their lifetime if material constraints are not met. Recently, we have gained deep insights into SOL dynamics by means of electromagnetic fluid turbulence simulations carried out with the Global Braginskii Solver (GBS). GBS is currently capabl

TORPEX is a basic plasma physics device where a simple magnetized torus (SMT) is produced by adding a small vertical magnetic field to a main toroidal component, generating helical field lines. The SMT configuration features the main ingredients of a tokamak Scrape-Off Layer (SOL), namely density gradients in the presence of magnetic field curvature and gradient. Recently, a toroidal in-vessel copper conductor has been installed in the TORPEX device. A current up to 1kA can be driven in the toroidal conduct

Negative triangularity tokamak plasmas are subject of an increased interest both in existing experiments and in studies of core physics as well as power handling relevant to the fusion demonstration power reactor. The ideal MHD stability calculations for the negative triangularity plasma extend the investigation of the TCV tokamak beta limits and edge stability to double null shapes, lower aspect ratio and negative shear. In case of the negative triangularity, the 2nd stability access is closed for ballooni

The TORoidal Plasma EXperiment (TORPEX) is a Simple Magnetized Torus (SMT) where open helical magnetic field lines are obtained from the superposition of a small vertical component on the main toroidal field. The SMT configuration features the main driving mechanisms of plasma instabilities characterising the Scrape-Off Layer (SOL) of larger tokamak devices, making TORPEX a very attractive machine to perform fusion oriented studies of plasma turbulence. A new experimental set-up has been recently developed

In the sheath region at the interface between plasmas and solid surfaces, quasi-neutrality and, in the case of magnetized plasmas, drift-ordering are violated. These two assumptions are typically made in plasma fluid models; the presence of a plasma-wall transition region, typical of all bounded systems, hampers therefore their use. This problem can be overcome by introducing a set of boundary conditions (BCs) for fluid models that properly describe the physics of the plasma-wall transition region. While th

The TORoidal Plasma EXperiment (TORPEX) is a basic plasma physics device where a Simple Magnetized Torus configuration (SMT) can be obtained superimposing a small vertical magnetic field component on the main toroidal field, resulting in open magnetic helical field lines. This configuration reproduces some of the main features of a tokamak plasma edge, including density and magnetic field gradient and curvature. In the last years, a complete study of electrostatic fluctuations and turbulence has been comple

In the foreseen upgrade of the Tokamak-a-Configuration-Variable (TCV) it is planned to add 3MW of additional RF power (3rd harmonic X-mode, X3, top-launch) to the present Electron Cyclotron (EC) system. With the upgrade of the EC-system, bringing the total EC power in X3-mode to 4.5MW, and the installation of 1 MW of neutral beam injection, a new avenue will be opened allowing the extensive study of H-mode physics in TCV. The envisaged new gyrotrons (lMW, 126GHz) are based on a minimum redesign of the 140 G

Personal audio logs are often recorded in multiple environments. This poses challenges for robust front-end processing, including speech/nonspeech detection (SND). Motivated by this, we investigate the robustness of four different privacy-sensitive features for SND, namely energy, zero crossing rate, spectral flatness, and kurtosis. We study early and late fusion of these features in conjunction with modeling temporal context. These combinations are evaluated in mismatched conditions on a dataset of nearly

Development of a 140 GHz, 1 MW, continuous wave gyrotron for the W7-X stellarator

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Ion Optics With Oval Apertures for TCV NBI

Fast ion transport in complex magnetic field configurations in TORPEX

A multi-model system-identification comparison with the global particle dynamics in TCV

Variability of MHD instabilities in benign termination of high-current runaway electron beams in the JET and DIII-D tokamaks

A Fast Double Null Control Concept Enabling Compact Fusion Reactors

Experimental characterization of inter-ELM modes in type-I ELMy scenarios at TCV using the thermal helium beam diagnostic

On the feasibility of Ohmically heated negative triangularity tokamak power plants

Progress on [N]TM modelling and control in the ITER Plasma Control System design

High Voltage Modulator for the TCV Diagnostic Neutral Beam Injector

On the interplay between plasma triangularity and micro-tearing turbulence

The Speed Submission to DIHARD II: Contributions & Lessons Learned

Status of the ITER Electron Cyclotron Heating and Current Drive System

A new generation plasma turbulence fluid code for tokamak scrape-off layer dynamics

Plasma turbulence studies in TORPEX basic plasma pyhsics device: from concentric flux surfaces to single null X-points

Stability limits for tokamak plasma with negative triangularity

Study of plasma fluctuations in new closed flux-surface configurations of the TORPEX experiment

The role of the sheath in magnetized plasma fluid turbulence

First results on the plasma fluctuations of the TORPEX device in the new magnetic field configurations

Millimeter Wave System Upgrades On TCV: Additional X3 Power And Fast ECE Polarizers

Evaluating the Robustness of Privacy-Sensitive Audio Features for Speech Detection in Personal Audio Log Scenarios