A5028335949- Magnetic confinement fusion research
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ITER
2018-2024
Royal Military Academy
2020
University of Lisbon
2008-2019
Culham Science Centre
2006-2018
Universidade Federal do Rio Grande do Norte
2018
Instituto Superior Técnico
2001-2017
Instituto Superior de Tecnologias Avançadas
2013-2017
Culham Centre for Fusion Energy
2008-2016
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2005-2016
Instituto de Engenharia de Sistemas e Computadores Investigação e Desenvolvimento
1999-2015
JET underwent a transformation from full carbon-dominated tokamak to fully metallic device with beryllium in the main chamber and tungsten divertor. This material combination is foreseen for activated phase of ITER. The ITER-Like Wall (ILW) experiment at shall demonstrate plasma compatibility walls reduction fuel retention. We report on set experiments (Ip = 2.0 MA, Bt 2.0–2.4 T, δ 0.2–0.4) different confinement conditions global gas balance analysis demonstrating strong long-term retention...
In ASDEX Upgrade, experimental efforts aim to establish pace making and mitigation of type-I edge localized modes (ELMs) in high confinement mode (H-mode) discharges. Injection small size cryogenic deuterium pellets (∼(1.4 mm)2 × 0.2 mm ≈ 2.5 1019 D) at rates up 83 Hz imposed persisting ELM control without significant fuelling, enabling for investigations well inside the regime. The approach turned out meet all required operational features. was realized with driving frequency ranging from 1...
This paper reports the impact on confinement and power load of high-shape 2.5 MA ELMy H-mode scenario at JET a change from all carbon plasma-facing components to an metal wall. In preparation this change, systematic studies reduction as result fuelling in combination with nitrogen seeding were carried out JET-C are compared their counterpart metallic An unexpected significant is reported decrease pedestal but partially recovered injection nitrogen.
A comparison of the L–H power threshold (Pthr) in JET with all carbon, JET-C, and beryllium/tungsten wall (the ITER-like choice), JET-ILW, has been carried out experiments slow input ramps matched plasma shapes, divertor configuration IP/BT pairs. The low density dependence threshold, namely an increase below a minimum ne,min, which was first observed MkII-GB C subsequently not current MkII-HD geometry, is again JET-ILW. At densities above Pthr reduced by ∼30%, ∼40% when radiation from bulk...
The replacement of the JET carbon wall (C-wall) by a Be/W ITER-like (ILW) has affected plasma energy confinement. To investigate this, experiments have been performed with both C-wall and ILW to vary heating power over wide range for plasmas different shapes.
In both JET and ASDEX Upgrade (AUG) the plasma energy confinement has been affected by presence of a metal wall requirement increased gas-fuelling to avoid tungsten pollution plasma.In with beryllium/tungsten high triangularity baseline H-mode scenario (i.e.similar ITER reference scenario) strongest benefit shaping give good normalised H 98 ~1 at Greenwald density fraction f GW ~0.8 disappeared.In AUG full could be achieved in plasmas, albeit elevated pressure β N >2.The lost respect carbon...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation M. N. A. Beurskens, T. H. Osborne, P. Schneider, E. Wolfrum, L. Frassinetti, R. Groebner, Lomas, I. Nunes, S. Saarelma, Scannell, B. Snyder, D. Zarzoso, Balboa, Bray, Brix, J. Flanagan, C. Giroud, Giovannozzi, Kempenaars, Loarte, de la Luna, G. Maddison, F. Maggi, McDonald, Pasqualotto, Saibene, Sartori, Emilia...
Abstract New experiments in 2013–2014 have investigated the physics responsible for decrease H-mode pedestal confinement observed initial phase of JET-ILW operation (2012 Experimental Campaigns). The effects plasma triangularity, global beta and neutrals on stability been systematically. pedestals is analysed framework peeling–ballooning model assumptions predictive code EPED. Low D content plasma, achieved either by low 2 gas injection rates or divertor configurations with optimum pumping,...
A new technique has been developed to produce plasmas with improved confinement relative the H98,y2 scaling law (ITER Physics Expert Groups on Confinement and Transport Modelling Database ITER Basics Editors EDA 1999 Nucl. Fusion 39 2175) JET tokamak. In mid-size tokamaks ASDEX upgrade DIII-D heating during current formation is used a flat q-profile minimum close 1. On this leads q-profiles similar q but opposite other not an state. By changing method utilizing faster ramp temporary higher...
Abstract Ion cyclotron resonance frequency (ICRF) heating has been an essential component in the development of high power H-mode scenarios Jet European Torus ITER-like wall (JET-ILW). The ICRF performance was improved by enhancing antenna-plasma coupling with dedicated main chamber gas injection, including preliminary minimization RF-induced plasma-wall interactions, while RF where optimized for core impurity screening terms ion position and minority hydrogen concentration. impact on...
In the recent JET experimental campaigns with new ITER-like wall (JET-ILW), major progress has been achieved in characterization and operation of H-mode regime metallic environments: (i) plasma breakdown at first attempt X-point L-mode recovered a few days operation; (ii) stationary stable type-I ELMy H-modes βN ∼ 1.4 have low high triangularity shape plasmas are showing that their operational domain H = 1 is significantly reduced JET-ILW mainly because need to inject large amount gas (above...
Type I ELMy H-mode operation in JET with the ITER-like Be/W wall (JET-ILW) generally occurs at lower pedestal pressures compared to those full carbon (JET-C). The density is similar but temperature where type ELMs occur reduced and below so-called critical I–type III transition reported JET-C experiments. Furthermore, confinement factor H98(y,2) baseline plasmas JET-ILW low power fractions Ploss/Pthr,08 < 2 (where Ploss (Pin − dW/dt), Pthr,08 L–H threshold from Martin et al 2008 (J. Phys....
In order to preserve the integrity of large tokamaks such as ITER, number disruptions has be limited. JET operated previously with a low frequency (i.e., disruption rate) 3.4% [P. C. de Vries et al., Nucl. Fusion 51, 053018 (2011)]. The start operations new full-metal ITER-like wall at showed marked rise in rate 10%. A full survey was carried out identify root causes, chain-of-events and classifying each disruption, similar previous analysis for carbon-wall operations. It improvements made...
The JET exploitation plan foresees D–T operations in 2020 (DTE2). With respect to the first campaign 1997 (DTE1), when was equipped with a carbon wall, experiments will be conducted presence of beryllium–tungsten ITER-like wall and benefit from an extended improved set diagnostics higher additional heating power (32 MW neutral beam injection + 8 ion cyclotron resonance heating). There are several challenges presented by new wall: general deterioration pedestal confinement; risk heavy...
Injection of cryogenic deuterium pellets has been successfully applied in ASDEX Upgrade for external edge localized mode (ELM) frequency control type-I ELMy H-mode discharge scenarios. A pellet velocity 560 m s−1 and a size about 6 × 1019 D-atoms was selected technical reasons, although even lower masses were found sufficient to trigger ELMs. moderate repetition rate close 20 Hz chosen avoid over-fuelling the core plasma. Pellet sequences up 4 s duration injected into discharges L–H...
Recent experiments at ASDEX Upgrade have achieved advanced scenarios with high βN (>3) and confinement enhancement over ITER98(y, 2) scaling, HH98y2 = 1.1–1.5, in steady state. These discharges been obtained a modified divertor configuration for Upgrade, allowing operation higher triangularity, changed neutral beam injection (NBI) system, more tangential, off-axis deposition. The figure of merit, βNHITER89-P, reaches up to 7.5 several seconds plasmas approaching stationary conditions....
ELM-free H-mode plasmas with stationary plasma density and radiation level are obtained in the ASDEX Upgrade tokamak large clearance between last closed flux surface wall, neutral beam injection a toroidal direction opposite to that of current. This behaviour is accompanied by characteristic narrow-band magnetohydrodynamic (MHD) oscillation clear harmonics up n = 11 visible. mode localized edge region. Conditions properties phases MHD closely resemble `quiescent H-mode' `edge harmonic...
Real-time simultaneous control of several radially distributed magnetic and kinetic plasma parameters is being investigated on JET, in view developing integrated advanced tokamak scenarios. This paper describes the new model-based profile controller which has been implemented during 2006–2007 experimental campaigns. The aims to use combination heating current drive (H&CD) systems—and optionally poloidal field (PF) system—in an optimal way regulate evolution parameter profiles such as...
To consolidate International Thermonuclear Experimental Reactor (ITER) design choices and prepare for its operation, Joint European Torus (JET) has implemented ITER's plasma facing materials, namely, Be the main wall W in divertor. In addition, protection systems, diagnostics, vertical stability control were upgraded heating capability of neutral beams was increased to over 30 MW. First results confirm expected benefits limitations all metal components (PFCs) but also yield understanding...
Experiments on JET with a carbon-fibre composite wall have explored the reduction of steady-state power load in an ELMy H-mode scenario at high Greenwald fraction ∼0.8, constant and close to L H transition. This paper reports systematic study due effect fuelling combination seeding over wide range pedestal density ((4–8) × 1019 m−3) detailed documentation divertor, main plasma conditions, as well comparative two extrinsic impurity nitrogen neon. It also impact overall behaviour, possible...
A reflectometry system has been developed for ASDEX Upgrade to measure the plasma profile from scrape-off layer until bulk plasma, simultaneously at high and low field sides. Unique features of are ultrafast broadband frequency modulation a continuous wave using solid state stable hyper abrupt tuned oscillators (down 10 μs), side channels fully remote control operation, via optical fiber links. Due special design transmission line, with decoupled in going out lines one-antenna configuration,...
We have analysed the edge stability of JET discharges with small localized modes (ELMs) using high resolution Thomson scattering system for accurate profiles in equilibrium reconstruction. For reference plasmas large Type I ELMs we confirm results from earlier analyses that is limited by intermediate-n peeling–ballooning a relatively radial extent. The double null configuration needed to replace smaller II considerably increases against these while n = ∞ ballooning not affected. When this...
The poloidal field (PF) coil system on ITER, which provides both feedforward and feedback control of plasma position, shape, current, is a critical element for achieving mission performance. Analysis PF capabilities has focused the 15 MA Q = 10 scenario with 300–500 s flattop burn phase. operating space available ELMy H-mode discharges in ITER upgrades to coils or associated systems establish confidence that objectives can be reached have been identified. Time dependent self-consistent...
Mitigation of type-I edge-localized modes (ELMs) was observed with the application an n = 2 field in H-mode plasmas on JET tokamak ITER-like wall (ILW). Several new findings ILW were identified and contrasted to previous carbon (C-wall) results for comparable conditions. Previous high collisionality C-wall saw little or no influence either 1 fields ELMs. However, recent observations show large ELMs a frequency ∼45 Hz replaced by high-frequency (∼200 Hz) small during field. With ILW,...
We present the pedestal structure, as determined from high-resolution Thomson scattering measurements, for a database of low and high triangularity (δ ≈ 0.22–0.39) 2.5 MA, type I ELMy H-mode JET plasmas after installation new ITER-like wall (JET-ILW). The explores effect increasing deuterium fuelling nitrogen seeding with view to explain observed changes in performance (edge global). JET-ILW show no significant change structure gas dosing. These results are good agreement EPED1 predictions....