Recent progress in small specimen test technology

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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

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

The comparison of simulations of plasma turbulence carried out with the GBS code, employing its latest multi-component plasma–neutral model, against a dedicated set of TCV discharges (TCV-X23) designed to investigate high-density divertor conditions characterised by strongly reduced target heat flux with respect to attached conditions, is presented. The TCV-X23 scenario, based on L-mode plasmas with a long outer divertor leg at low toroidal field, provides a well-diagnosed reference for boundary turbule

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

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

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

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

A W-2Y material has been produced by powder metallurgy techniques including mechanical alloying of W and Y elemental powders in an argon atmosphere, followed by hot isostatic pressing of the milled powder at 1320 degrees C under a pressure of 200 MPa for 2 ...

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

In order to address non-local effects in turbulent transport of magnetic-fusion devices, the gyrokinetic code GENE has been extended from a flux tube to a more global geometry. This global version of GENE includes radial variations of temperature and density profiles, as well as of magnetic equilibrium quantities. Non-periodic radial boundary conditions allow for profile evolution. Thanks to an interface with the MHD equilibrium code CHEASE, as well as the implementation of various types of source and sink

Modulation of power amplitude is a widespread to determine the radial absorption profile of externally launched power in fusion plasmas. There are many techniques to analyze the plasma response to such a modulation. The break-in-slope (BIS) analysis can draw an estimated power deposition profile for each power step up. In this paper, the BIS analysis is used to monitor the power deposition location of one or two EC power beams simultaneously in a non-stationary plasma being displaced vertically in the TCV t

The Tokamak a Configuration Variable (TCV) tokamak is equipped with high-power (4.5 MW), real-time-controllable EC systems and flexible shaping, and plays an important role in fusion research by broadening the parameter range of reactor relevant regimes, by investigating tokamak physics questions and by developing new control tools. Steady-state discharges are achieved, in which the current is entirely self-generated through the bootstrap mechanism, a fundamental ingredient for ITER steady-state operation.

The issues of fusion with client-dependent and confidence information have been well studied separately in biometric authentication. In this study, we propose to take advantage of both sources of information in a discriminative framework. Initially, each source of information is processed on a per expert basis (plus on a per client basis for the first information and on a per example basis for the second information). Then, both sources of information are combined using a second-level classifier, across dif

A 'hybrid' scenario for ITER is defined through its objectives: a large fusion yield for a long time duration. In many tokamaks, discharges characterized by a stationary current density profile, enclosing a large volume of low magnetic shear with q(0) near 1, have achieved improved confinement and higher beta limits. Their extrapolation to ITER from existing data corresponds to the ITER hybrid scenario. These discharges are characterized by soft MHD events. Physics issues relevant to the existence and extra

The particle confinement in a magnetized plasma torus with superimposed vertical magnetic field is modeled and measured experimentally. The formation of an equilibrium characterized by a parallel plasma current canceling out the grad B and curvature drifts is described using a two-fluid model. Characteristic response frequencies and relaxation rates are calculated. The predictions for the particle confinement time as a function of the vertical magnetic field are verified in a systematic experimental study o

A diagnostic neutral beam injector (DNBI) [CRPP report LRP 710/01, CRPP-EPFL, 200 1; EPS Conf. Comr. Fusion Plasma Phys., 25A (2001) 365] has been installed on tokamak A configuration variable (TCV) [Plasma Phys. Control Fusion, 36 (1994) 13277; Plasma Phys. Control Fusion, 43 (200 1) A 16 1; Plasma Phys. Control Fusion, to be published] for the purpose of providing local measurements of plasma ion temperature, velocity and impurity density by Charge exchange recombination spectroscopy (CXRS) [EPS Conf. Con

A high-density, ELM-free, 'enhanced Dalpha' (EDA) H-mode has been demonstrated with Ohmic or RF heating on the Alcator C-Mod device. An allied 'low particle confinement' H-regime was also observed previously in 'Mk0' divertor experiments on JET. Initial attempts to recover similar states in the JET 'MkIIGB' divertor configuration are reported, employing appropriately shaped magnetic equilibria. Comparisons between cases with and without divertor cryopumping show enhanced edge sources tend to increase ELM fr

Recent progress in small specimen test technology

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Fast ion transport in complex magnetic field configurations in TORPEX

Ion Optics With Oval Apertures for TCV NBI

Power exhaust and detachment with varying outer leg length using turbulence simulations and experiments designed for validation

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

On the feasibility of Ohmically heated negative triangularity tokamak power plants

The Speed Submission to DIHARD II: Contributions & Lessons Learned

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

Processing and characterization of a W–2Y material for fusion power reactors

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

Development of a Global Version of the Gyrokinetic Microturbulence Code GENE

Simultaneous Power Deposition Detection of Two EC Beams with the BIS Analysis in Moving TCV Plasmas

Overview of Physics Research on the TCV Tokamak

A Novel Approach to Combining Client-Dependent and Confidence Information in Multimodal Biometric

Hybrid advanced scenarios: perspectives for ITER and new experiments with dominant RF heating

Effects of a vertical magnetic field on particle confinement in a magnetized plasma torus

A Novel Approach to Combining Client-Dependent and Confidence Information in Multimodal Biometric

Upgrade of the diagnostic neutral beam injector for the TCV tokamak

ELM moderation with ICRF heating on JET