P. Aleynikov
A5011154718- Magnetic confinement fusion research
- Fusion materials and technologies
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- Nuclear Physics and Applications
- Dust and Plasma Wave Phenomena
- High-pressure geophysics and materials
- Nuclear Materials and Properties
- Nuclear reactor physics and engineering
- Atomic and Subatomic Physics Research
- Advanced Data Storage Technologies
- Atomic and Molecular Physics
- Particle Accelerators and Free-Electron Lasers
- Advanced Chemical Physics Studies
- Semiconductor materials and devices
- High-Energy Particle Collisions Research
- Electron and X-Ray Spectroscopy Techniques
- Vacuum and Plasma Arcs
- Engineering Applied Research
- Nuclear Engineering Thermal-Hydraulics
- Lightning and Electromagnetic Phenomena
Max Planck Institute for Plasma Physics - Greifswald
2016-2024
ITER
2014-2024
Max Planck Institute for Plasma Physics
2015-2024
CEA Cadarache
2021
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2021
Max Planck Society
2015-2021
Royal Military Academy
2020
Princeton University
2018
University of California, San Diego
2018
General Atomics (United States)
2018
An overview of the present status research toward final design ITER disruption mitigation system (DMS) is given. The DMS based on massive injection impurities, in order to radiate plasma stored energy and mitigate potentially damaging effects disruptions. this will be extremely challenging due many physics engineering constraints such as limitations port access amount species injected impurities. Additionally, questions relevant remain unsolved mechanisms for mixing assimilation impurities...
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...
Of all electrons, runaway electrons have long been recognized in the fusion community as a distinctive population. They now attract special attention part of ITER mission considerations. This review covers basic physics ingredients phenomenon and ongoing efforts (experimental theoretical) aimed at electron (RE) taming next generation tokamaks. We emphasize prevailing themes last 20 years: hot-tail mechanism production, RE interaction with impurity ions, role synchrotron radiation kinetics,...
Abstract The JET 2019–2020 scientific and technological programme exploited the results of years concerted engineering work, including ITER-like wall (ILW: Be W divertor) installed in 2010, improved diagnostic capabilities now fully available, a major neutral beam injection upgrade providing record power 2019–2020, tested technical procedural preparation for safe operation with tritium. Research along three complementary axes yielded wealth new results. Firstly, plasma delivered scenarios...
Abstract In 2021 JET exploited its unique capabilities to operate with T and D–T fuel an ITER-like Be/W wall (JET-ILW). This second major campaign (DTE2), after DTE1 in 1997, represented the culmination of a series enhancements—new fusion diagnostics, new injection capabilities, refurbishment plant, increased auxiliary heating, in-vessel calibration 14 MeV neutron yield monitors—as well as significant advances plasma theory modelling community. DTE2 was complemented by sequence isotope...
The 2014–2016 JET results are reviewed in the light of their significance for optimising ITER research plan active and non-active operation. More than 60 h plasma operation with first wall materials successfully took place since its installation 2011. New multi-machine scaling type I-ELM divertor energy flux density to is supported by principle modelling. relevant disruption experiments modelling reported a set three mitigation valves mimicking setup. Insights L–H power threshold Deuterium...
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,...
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...
Abstract For the past several years, JET scientific programme (Pamela et al 2007 Fusion Eng. Des . 82 590) has been engaged in a multi-campaign effort, including experiments D, H and T, leading up to 2020 first with 50%/50% D–T mixtures since 1997 ever plasmas ITER mix of plasma-facing component materials. this purpose, concerted physics technology was launched view prepare campaign (DTE2). This paper addresses key elements developed by directly contributing preparation. intense preparation...
For the first time it is experimentally demonstrated on JET tokamak that a combination of low impurity concentration bulk plasma and large magnetohydrodynamic instabilities able to suppress relativistic electron beams without measurable heat loads onto facing components. Magnetohydrodynamic simulations instability modeling postinstability confirm prompt loss runaways absence regeneration during final current collapse. These surprising findings motivate new approach dissipate runaway...
This Letter presents a rigorous kinetic theory for relativistic runaway electrons in the near critical electric field tokamaks. The provides distribution function of electrons, reveals presence two different threshold fields, and describes mechanism hysteresis electron avalanche. Two fields characterize minimal required sustainment existing population higher avalanche onset. near-threshold regime determines time scale toroidal current decay during mitigation
The objective of thermonuclear fusion consists producing electricity from the coalescence light nuclei in high temperature plasmas. most promising route to envisages confinement such plasmas with magnetic fields, whose studied configuration is tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one main potential showstoppers on a commercial reactor. In this work we report how, deploying innovative analysis methods thousands JET experiments covering isotopic...
Relativistic electron (RE) beams at high current density (low safety factor, qa) yet very low free-electron accessed with D2 secondary injection in the DIII-D and JET tokamak are found to exhibit large-scale MHD instabilities that benignly terminate RE beam. In JET, this technique has enabled termination of MA-level currents without measurable first-wall heating. This scenario thus offers an unexpected alternate pathway achieve mitigation collisional dissipation. Benign is explained by two...
Abstract In the initial stages of plasma initiation in Wendelstein7-X stellarator with electron-cyclotron-resonance heating, a downshifted electron cyclotron emission signal is observed. Due to absence corresponding up-shifted signal, this believed come from energetic electrons ($\sim$10 keV).
 We propose mechanism for generation these fast based on overlap resonances flux surfaces close centre plasma.
 Multiple passages through lead stochasticization particle trajectories,...
Abstract This paper explores the process of Runaway Electron (RE) formation during start-up a tokamak discharge. has been done by simulating RE generation and, importantly their losses, self-consistently with behavior many other discharge parameters, using SCENPLINT code, which updated to include physics. For first time, an attempt is made compare such simulations experimental observations on at JET. proved be difficult task due parameters that are calculated possible explosive growth and...
Abstract We review the physics of energetic particles (EPs) in magnetically confined burning fusion plasmas with focus on advances since last update ITER Physics Basis (Fasoli et al 2007 Nucl. Fusion 47 S264). Topics include basic EP physics, generation, diagnostics EPs and instabilities, interaction thermal plasma EP-driven particle modes (EPMs), turbulence, linear nonlinear stability simulation instabilities EPMs, 3D effects, scenario optimization strategies based phase-space control,...
Runaway electrons (REs) generated during disruption events in tokamaks have to be mitigated minimize the detrimental impact from their massive losses wall, especially ITER. RE-driven micro-instabilities, such as whistlers and magnetized plasma waves, can cause enhanced RE scattering thereby alleviate mitigation problem. This work presents a newly developed ray-tracing code COIN which enables stability analysis of runaway-driven waves tokamak. The uses standard procedure calculate wave-packet...
This work provides a systematic description of electron kinetics during impurity dominated thermal quenches. A Fokker–Planck equation for the hot electrons and power balance bulk plasma are solved self-consistently, with radiation as dominant energy loss mechanism. We find that runaway production is facilitated by heavy injection impurities up to prompt conversion total current into sub-MeV current. also formation less efficient in plasmas high pre-quench temperatures predict significant...
Abstract Runaway electrons (REs) created during tokamak disruptions pose a threat to the reliable operation of future larger machines. Experiments using shattered pellet injection (SPI) have been carried out at JET investigate ways prevent their generation or suppress them if avoidance is not sufficient. Avoidance possible SPI contains sufficiently low fraction high-Z material, it fired early in advance disruption prone runaway generation. These results are consistent with previous similar...
Areas of agreement and disagreement with present-day models runaway electron (RE) evolution are revealed by measuring MeV-level bremsstrahlung radiation from electrons (REs) a pinhole camera. Spatially resolved measurements localize the RE beam, reveal energy-dependent transport, can be used to perform full two-dimensional (energy pitch-angle) inversions phase-space distribution. Energy-resolved find qualitative modeling on role collisional synchrotron damping in modifying distribution...
Systematic variation of the pre-disruption core electron temperature (Te) from 1 to 12 keV using an internal transport barrier scenario reveals a dramatic increase in production seed runaway electrons (REs), ultimately accessing near-complete conversion current into sub-MeV RE current. Injected Ar pellets are observed ablate more intensely and promptly as Te rises. At high Te, ablation exceeds predictions published thermal models. Simultaneously, quench (TQ) is significantly shorten with...
Abstract DIII-D physics research addresses critical challenges for the operation of ITER and next generation fusion energy devices. This is done through a focus on innovations to provide solutions high performance long pulse operation, coupled with fundamental plasma understanding model validation, drive scenario development by integrating core boundary plasmas. Substantial increases in off-axis current efficiency from an innovative top launch system EC power, pressure broadening Alfven...