A5085530056- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Solar and Space Plasma Dynamics
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- Atomic and Molecular Physics
- Nuclear reactor physics and engineering
- Astro and Planetary Science
- Advanced Image Processing Techniques
- Dust and Plasma Wave Phenomena
- Nuclear Physics and Applications
- Astronomical Observations and Instrumentation
- Fluid Dynamics and Turbulent Flows
- Spacecraft and Cryogenic Technologies
- Advanced MRI Techniques and Applications
- Geomagnetism and Paleomagnetism Studies
- Neural Networks and Applications
- Advanced Vision and Imaging
- Silicon and Solar Cell Technologies
- Quantum Chromodynamics and Particle Interactions
- Neural Networks Stability and Synchronization
Universidad Complutense de Madrid
2016-2025
Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
2014-2024
Fusion (United States)
2022-2023
Unidades Centrales Científico-Técnicas
2015-2021
Princeton Plasma Physics Laboratory
2005-2021
Fusion for Energy
2021
HUN-REN Centre for Energy Research
2021
Max Planck Institute for Plasma Physics
2016-2020
Max Planck Society
2015-2020
Max Planck Institute for Plasma Physics - Greifswald
2016-2020
Abstract The optimized superconducting stellarator device Wendelstein 7-X (with major radius , minor and plasma volume) restarted operation after the assembly of a graphite heat shield 10 inertially cooled island divertor modules. This paper reports on results from first high-performance operation. Glow discharge conditioning ECRH discharges in helium turned out to be important for density edge radiation control. Plasma densities with central electron temperatures were routinely achieved...
Abstract Research on magnetic confinement of high-temperature plasmas has the ultimate goal harnessing nuclear fusion for production electricity. Although tokamak 1 is leading toroidal magnetic-confinement concept, it not without shortcomings and community therefore also pursued alternative concepts such as stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) field geometry. The availability this additional dimension opens up an extensive configuration...
Disruption mitigation is mandatory for ITER in order to reduce forces, mitigate heat loads during the thermal quench and avoid runaway electrons (REs). A fast disruption valve has been installed at JET study by massive gas injection. Different species amounts have investigated with respect timescales efficiency. We discuss of halo currents as well sideways forces vertical displacement events, increased energy dissipation through radiation, which could arise asymmetric radiation suppression REs.
After completing the main construction phase of Wendelstein 7-X (W7-X) and successfully commissioning device, first plasma operation started at end 2015. Integral start-up using electron cyclotron resonance heating (ECRH) an extensive set diagnostics have been completed, allowing initial physics studies during operational campaign. Both in helium hydrogen, breakdown was easily achieved. Gaining experience with vessel conditioning, discharge lengths could be extended gradually. Eventually,...
The optimized, superconducting stellarator Wendelstein 7-X went into operation and delivered first measurement data after 15 years of construction one year commissioning. Errors in the magnet assembly were confirmend to be small. Plasma was started with 5 MW electron cyclotron resonance heating (ECRH) power five inboard limiters. Core plasma values keV, keV at line-integrated densities achieved, exceeding original expectations by about a factor two. Indications for core-electron-root found....
Abstract Fusion energy research has in the past 40 years focused primarily on tokamak concept, but recent advances plasma theory and computational power have led to renewed interest stellarators. The largest most sophisticated stellarator world, Wendelstein 7-X (W7-X), just started operation, with aim show that earlier weaknesses of this concept been addressed successfully, intrinsic advantages persist, also at parameters approaching those a future fusion plant. Here we first physics...
Wendelstein 7-X is the first comprehensively optimized stellarator aiming at good confinement with plasma parameters relevant to a future power plant. Plasma operation started in 2015 using limiter configuration. After installing an uncooled magnetic island divertor, extending energy limit from 4 80 MJ, continued 2017. For this phase, electron cyclotron resonance heating (ECRH) capability was extended 7 MW, and hydrogen pellet injection implemented. The enhancements resulted highest triple...
A significant improvement of plasma parameters in the optimized stellarator W7-X is found after injections frozen hydrogen pellets. The ion temperature post-pellet phase exceeds 3 keV with 5 MW electron heating and global energy confinement time surpasses empirical ISS04-scaling. realized such experiments are significantly above those comparable gas-fuelled discharges. In this paper, we present details these pellet discuss main properties during enhanced phases. Local power balance applied...
The first experimental evidence showing the connection between blob/hole formation and zonal-flow generation was obtained in edge plasma of JET tokamak. Holes as well blobs are observed to be born shear layer, where zonal-flows off meso-scale coherent structures, leading disconnection positive negative pressure perturbations. newly formed transport azimuthal momentum up gradient flow drive while moving outwards. During this process energy is transferred from structures zonal flows via...
The neoclassical transport optimization of the Wendelstein 7-X stellarator has not resulted in predicted high energy confinement gas fueled electron-cyclotron-resonance-heated (ECRH) plasmas as modelled (Turkin et al 2011 Phys. Plasmas 18 022505) due to levels turbulent heat observed experiments. electron-turbulent-heat appears non-stiff and is electron temperature gradient (ETG)/ion (ITG) type (Weir 2021 Nucl. Fusion 61 056001). As a result, Te can be varied freely from 1 keV–10 keV within...
Abstract We present recent highlights from the most operation phases of Wendelstein 7-X, advanced stellarator in world. Stable detachment with good particle exhaust, low impurity content, and energy confinement times exceeding 100 ms, have been maintained for tens seconds. Pellet fueling allows plasma reduced ion-temperature-gradient turbulence, during such phases, overall is so (energy often 200 ms) that attained density temperature profiles would not possible less optimized devices, since...
Plasma production in stellarators with ion cyclotron heating is complementary to the widely used electron (ECRH). The prospective light minority scenario developed and tried on Uragan-2M Large Helical Device (LHD) had been reexamined at LHD. distinctive feature of this attempt that parameters plasma produced are better than before comparable those by ECRH. This new possibility heating, if it becomes practical, motivates rethinking role stellarator machines.
The first experimental campaign of the TJ-II stellarator has been conducted using electron cyclotron resonance heating (, ) with a pulse length . flexibility device used to study five different configurations varying plasma volume and rotational transform. In this paper, main results are presented and, in particular, influence plasma-wall interaction phenomena on confinement is briefly discussed.
This paper presents the latest results on confinement studies in TJ-II stellarator. The inherently strong plasma–wall interaction of has been successfully reduced after lithium coating by vacuum evaporation. Besides H retention and low Z , Li was chosen because there exists a reactor-oriented interest this element, thus giving special relevance to investigation its properties. Li-coating led important changes plasma performance. Particularly, effective density limit NBI plasmas extended...
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...
For stellarators, which need no or only small amounts of current drive, electron-cyclotron-resonance heating (ECRH) is a promising method even for the envisaged application in fusion power plant. Wendelstein 7-X (W7-X) equipped with steady-state capable ECRH system, operating at 140 GHz, corresponds to 2nd cyclotron harmonic electrons magnetic field 2.5 T. Ten gyrotrons are operational and already delivered 7 MW W7-X plasmas. Combined pellet injection, highest triple product (0.68 × 1020 keV...
The results from the investigation of neoclassical core transport and role radial electric field profile (Er) in first operational phase Wendelstein 7-X (W7-X) stellarator are presented. In plasmas, details Er expected to have a strong effect on both particle heat fluxes. Investigation is important understanding validation calculations. closely related perpendicular plasma flow (u⊥) through force balance equation. This allows be inferred measurements velocity, which can measured using x-ray...
We theoretically assess two mechanisms thought to be responsible for the enhanced performance observed in plasma discharges of Wendelstein 7-X stellarator experiment fueled by pellet injection. The effects ambipolar radial electric field and electron density peaking on turbulent ion heat transport are separately evaluated using large-scale gyrokinetic simulations. essential role magnetic geometry is demonstrated, comparison with a tokamak.
The Charge Exchange Recombination Spectroscopy (CXRS) diagnostic has become a routine on almost all major high temperature fusion experimental devices. For the optimized stellarator Wendelstein 7-X (W7-X), highly flexible and extensive CXRS been built to provide high-resolution local measurements of several important plasma parameters using recently commissioned neutral beam heating. This paper outlines design specifics W7-X system gives examples initial results obtained, including typical...
Pulsed injections of boron carbide granules into Wendelstein 7-X stellarator (W7-X) plasmas transiently increase the plasma stored energy and core ion temperatures above reference W7-X experimental programs by up to 30%. In a series 4 MW electron cyclotron resonance heating experiments, PPPL Probe Mounted Powder Injector provided 50 ms bursts 100 μm every 350 at estimated quantities ranging from approximately 1 mg/pulse over 30 mg/pulse. For each injection, was observed initially drop...
This paper describes a series of experiments performed in TJ-II stellarator with the aim studying influence magnetic configuration on stability and transport properties plasmas. Plasma potential profiles have been measured several configurations up to plasma core heavy ion beam probe diagnostic. Low-order rational surfaces positioned at different radii observing effect features. edge turbulent has studied that are marginally stable due decreased well. Results show dynamical coupling between...
A new pellet injection system was installed at JET designed for both fuelling and ELM pacing. The purpose of the pacing section to validate as a suitable tool mitigation in ITER. Pellet confirmed large size scale JET. dynamics triggered ELMs investigated with respect their spontaneous counterparts. Triggered show features also typical several operational regimes. Since none these regimes unsettled by pellets this is strong hint compatibility other plasma control tools. Observations modelling...
The impurity transport in magnetically confined plasmas under some conditions finds neither quantitatively nor qualitatively a satisfactory theory-based explanation. This compromises the successful realization of thermo-nuclear fusion for energy production since accumulation is known to be one causes that limits plasma performance through radiative losses and dilution. Under stellarator reactor-relevant conditions, supported by negative (inwards pointing) radial electric field which must...