T. S. Pedersen
A5013770927- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Atomic and Molecular Physics
- Laser-Plasma Interactions and Diagnostics
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Muon and positron interactions and applications
- Solar and Space Plasma Dynamics
- Laser-induced spectroscopy and plasma
- Dust and Plasma Wave Phenomena
- Particle Accelerators and Free-Electron Lasers
- Nuclear reactor physics and engineering
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Nuclear Physics and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- Atomic and Subatomic Physics Research
- Stellar, planetary, and galactic studies
- Spacecraft and Cryogenic Technologies
- Gas Dynamics and Kinetic Theory
- Fluid Dynamics and Turbulent Flows
- Astronomy and Astrophysical Research
- Geomagnetism and Paleomagnetism Studies
Max Planck Institute for Plasma Physics - Greifswald
2015-2024
Madison Group (United States)
2023-2024
Energy Center of Wisconsin
2024
Universität Greifswald
2015-2023
Czech Academy of Sciences, Institute of Plasma Physics
2020-2023
Max Planck Institute for Plasma Physics
2012-2021
Max Planck Society
2012-2021
University of California, San Diego
2015-2021
The University of Tokyo
2015-2020
Lawrence University
2020
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...
Regimes of high-confinement mode have been studied in the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. with no edge localized modes (ELM-free) compared detail to a new regime, enhanced Dα (EDA). EDA discharges only slightly lower energy confinement than comparable ELM-free ones, but show markedly reduced impurity confinement. Thus do not accumulate impurities and typically fraction radiated power. The gradients seem be relaxed by continuous process rather an...
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,...
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...
Wendelstein 7-X is a highly optimized stellarator that went into operation in 2015. With 30 cubic meter volume, superconducting coil system operating at 2.5 T, and steady-state heating capability of eventually up to 10 MW, it was built demonstrate the benefits stellarators parameters approaching those fusion power plant. We report here on first results with test divertor installed, during second phase, which performed half 2017. Operation divertor, addition several new fueling systems,...
Electron–positron plasmas are unique in their behavior due to the mass symmetry. Strongly magnetized electron–positron, or pair, present a number of astrophysical settings, such as jets, but they have not yet been created laboratory. Plans for creation and diagnosis pair stellarator presented, based on extrapolation results from Columbia Non-neutral Torus stellarator, well recent developments positron sources. The particular challenges positronium injection plasma diagnostics addressed.
The next step in the Wendelstein stellarator line is large superconducting device 7-X, currently under construction Greifswald, Germany. Steady-state operation an intrinsic feature of stellarators, and one key element 7-X mission to demonstrate steady-state plasma conditions relevant for a fusion power plant. device, on hand, requires implementation special technologies, giving rise technical challenges during design, fabrication assembly such device. On other also physics development at...
The first physics operation phase on the stellarator experiment Wendelstein 7-X was successfully completed in March 2016 after about 10 weeks of operation. Experiments this were conducted with five graphite limiters as primary plasma-facing components. Overall, results beyond expectations published shortly before start [Sunn Pedersen et al., Nucl. Fusion 55, 126001 (2015)] both respect to parameters reached and themes addressed. We report here some most important plasma experiments that...
Wendelstein 7-X (W7-X) is currently under commissioning in preparation for its initial plasma operation phase, phase 1.1 (OP1.1). This first serves primarily to provide an integral of all major systems needed operation, as well systems, such diagnostics, that need verify their foreseen functions. In OP1.1, W7-X will have a reduced set in-vessel components. particular, five graphite limiter stripes replace the later divertor. paper describes expected machine capabilities selection physics...
Wendelstein 7-X aims at quasi-steady state operation with up to 10 MW of heating power for 30 min. Power exhaust will be handled predominantly via actively water cooled CFC (carbon-fiber-reinforced carbon) based divertor units designed withstand loads MW/m2 locally in steady state. If local exceed this value, a risk delamination the and failure entire modules arises. Infrared endoscopes monitor all main plasma facing components are being prepared, near real time software tools under...
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...
Abstract Wendelstein 7-X (W7-X), the largest advanced stellarator, is built to demonstrate high power, performance quasi-continuous operation. Therefore, in recent campaign, experiments were performed prepare for long pulse operation, addressing three critical issues: development of stable detachment, control heat and particle exhaust, impact leading edges on plasma performance. The exhaust W7-X realized with help an island divertor, which utilizes large magnetic islands at boundary. This...
A plasma confined in a dipole field exhibits unique equilibrium and stability properties. In particular, equilibria exist at all beta values these are found to be stable ballooning modes when they interchange stable. When kinetic treatment is performed low beta, drift temperature gradient mode also which couples the MHD vicinity of marginal stability.
In traditional electron/ion laboratory plasmas, the system size $L$ is much larger than both plasma skin depth $l_{s}$ and Debye length $\unicode[STIX]{x1D706}_{D}$ . current planned efforts to create electron/positron plasmas in laboratory, this not necessarily case. A low-temperature, low-density may have $\unicode[STIX]{x1D706}_{D}<L<l_{s}$ ; a high-density, thermally relativistic $l_{s}<L<\unicode[STIX]{x1D706}_{D}$ Here we consider question of what physics phenomena are...
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 Wendelstein 7-X (W7-X) optimized stellarator fusion experiment, which went into operation in 2015, has been operating since 2017 with an un-cooled modular graphite divertor. This allowed first divertor physics studies to be performed at pulse energies up 80 MJ, as opposed 4 MJ the phase, where five inboard limiters were installed instead of a This, and number other upgrades device capabilities, extension regimes higher plasma density, heating power, performance overall, e.g. setting new...
We describe here efforts to create and study magnetized electron–positron pair plasmas, the existence of which in astrophysical environments is well-established. Laboratory incarnations such systems are becoming ever more possible due novel approaches techniques plasma, beam laser physics. Traditional plasmas studied date, both nature laboratory, exhibit a host different wave types, many generically unstable evolve into turbulence or violent instabilities. This complexity instability these...
High resolution measurements on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1551 (1994)] of transport barrier in “Enhanced Dα” (EDA) regime, which has increased particle without large edge localized modes, show steep density and temperature gradients over a region 2–5 mm, with peak pressure up to 12 MPa/m. Evolution pedestal at L-H transition is consistent large, rapid drop thermal conductivity across barrier. A quasi-coherent fluctuation density, potential, Bpol,...
Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters December 2015. At end of 10 weeks long experimental campaign (OP1.1) more than 20 independent diagnostic systems were operation, allowing detailed studies many interesting plasma phenomena. For example, fast neutral gas manometers supported video cameras (including one fast-frame camera frame rates...
The results of a first systematic assessment plasma edge transport processes for the limiter startup configuration at Wendelstein 7-X are presented. This includes an investigation from intrinsic and externally injected impurities their impact on power balance heat fluxes. fully 3D coupled fluid kinetic neutral Monte Carlo code EMC3-EIRENE is used.
BAR domains are dimeric protein modules that sense, induce, and stabilize lipid membrane curvature. Here, we show curvature sensing (MCS) directs cellular localization function of the domain PICK1. In PICK1, homologous proteins ICA69 arfaptin2, identify an amphipathic helix N-terminal to mediates MCS. Mutational disruption in PICK1 impaired MCS without affecting binding per se. insulin-producing INS-1E cells, super-resolution microscopy revealed selectively compromised density on insulin...
For the first time, optimized stellarator Wendelstein 7-X has operated with an island divertor. An operation regime in hydrogen was found which total plasma radiation approached absorbed heating power without noticeable loss of stored energy. The divertor thermography recorded simultaneously a strong reduction heat load on all targets, indicating almost complete detachment. This stably sustained over several energy confinement times until preprogrammed end discharge. is mainly due to oxygen...
The main objective of the Wendelstein 7-X (W7-X) stellarator is to demonstrate integrated reactor potential optimized line. An important element this mission achievement high heating-power and confinement in steady-state operation. Such an plasma operation has not yet been demonstrated represents major scientific goal W7-X. way towards staged. In first phase, called OP 1.1, December 2015-March 2016, a limiter configuration was used. paper, preparation phase as well lessons learned during...