A5064460624- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Plasma Diagnostics and Applications
- Advanced Fiber Optic Sensors
- High-pressure geophysics and materials
- Advanced Fiber Laser Technologies
- Gas Dynamics and Kinetic Theory
- Simulation and Modeling Applications
- Analytical Chemistry and Sensors
- Thermal Radiation and Cooling Technologies
- Viral Infections and Vectors
- Radiation Effects in Electronics
- Photonic Crystal and Fiber Optics
- Climate variability and models
- Carbon Nanotubes in Composites
- Optical Network Technologies
- Industrial Technology and Control Systems
- Catalysis and Oxidation Reactions
- Mechanical Engineering and Vibrations Research
- GNSS positioning and interference
Max Planck Institute for Plasma Physics
2016-2025
Culham Science Centre
2024
Culham Centre for Fusion Energy
2024
Technical University of Munich
2018-2021
Max Planck Society
2016-2021
Southwestern Institute of Physics
2014-2017
Huazhong University of Science and Technology
2012
Peking University
2003
Abstract Based on particle and energy balances, a reduced model is derived for the physical mechanisms leading to occurrence of stable unstable X-point radiators (XPRs), latter also known as marfes. The roles neutral deuterium density in divertor region initiating XPRs highlighted. An access condition formulated whose parameter dependencies are consistent with experimental observations which could apply process detachment. With an exponential increase recombination rate at low temperature,...
Future fusion reactors require a safe, steady-state divertor operation. With deep detachment, which is typically induced by impurity seeding, the radiation concentrates in small region at X-point or on closed flux surfaces above X-point. This so-called radiator (XPR) moves further inside confined with increasing seeding and location can be actively controlled. At AUG, parameter space for operation an XPR was significantly extended, using active feedback location. The observed nearly whole...
We present a novel concept to tackle the power exhaust challenge of magnetically confined fusion plasma. It relies on prior establishment an X-point radiator that dissipates large fraction before it reaches divertor targets. Despite spatial proximity magnetic X point confinement region, this singularity is far away from hot plasma in coordinates and therefore allows coexistence cold dense with high potential radiate. In compact radiative (CRD) target plates are placed close point. here...
Abstract The X-point radiator (XPR) is an attractive scenario that may contribute to solving the power exhaust problem in future fusion devices. 2D transport code SOLPS-ITER was applied reproduce experimentally measured plasma condition with XPR ASDEX Upgrade tokamak and compare a reduced model. Neutrals penetrating from adjoining cold divertor region large connection length near play important role initiating XPR. However, once such created, it persists even if fueling impurity seeding...
Abstract The physics governing the height of X-point radiator and influence related radiation losses on edge temperature profiles is studied with a reduced power balance model, which an extension model developed to study access. For ASDEX Upgrade parameters heating 10 MW, reproduces that can be moved from up 14 cm into confined plasma, dissipating 70 % power. key parameter neutral density in region. A reduction kinetic pressure gradient about 50 found could explain suppression localized modes...
Abstract Extrapolating the observed behavior of helium exhaust in current tokamaks towards future reactors requires understanding underlying physical mechanisms determining transport, recycling and pumping. Helium compression is main physics-based figure merit characterizing how efficiently transported divertor recycled at target plates. Moreover, gas transport subdivertor region pumps strongly influenced by vessel geometry installed pumps.
The SOLPS-ITER code package used to model...
Abstract The capabilities of the newly installed divertor Thomson Scattering (DTS) diagnostic (Kurzan et al 2021 J. Inst. 16 C09012) at ASDEX Upgrade (AUG) have been demonstrated by measuring 2D electron densities n e and temperatures T from attached to fully detached conditions in L- H-mode. collected dataset is a breakthrough for studies AUG which such measurements so far missing. Besides highlighting strengths limits DTS system, this work provides confirmations new insights into...
Abstract We report on the first SOLPS-ITER simulations of a low-field side snowflake minus (LFS SF − ) divertor configuration with drifts fully activated in ASDEX Upgrade. Compared to reference case without drifts, simulation normal toroidal magnetic field ( B × ∇ points primary X-point) shows larger low-field-side/high-field-side asymmetry, an enhanced radial cross transport, as well flux redistribution between and secondary strike points. Although small compared total input power, power is...
We report on the first SOLPS simulations of a low-field side snowflake minus (LFS SF−) configuration in ASDEX Upgrade (AUG). This will become accessible AUG after foreseen hardware modification its upper divertor. Spatially constant transport coefficients, an input power 5 MW and nitrogen seeding rate leading to radiative fraction 86% were assumed. is 9% higher than that for single null reference with same similar upstream parameters separatrix impurity concentrations. As consequence LFS SF−...
Self-organized criticality (SOC) dynamics have been investigated in non-local transport regimes induced by the supersonic molecular beam injection HL-2A tokamak. Experimental evidence shows that SOC or avalanche behaviors, such as Hurst parameter, self-similarity and large-scale radial correlations turbulence, are remarkably enhanced during prompt phase, together with an increase of inward propagation turbulent events. These results highlight importance paradigm transient thermal...
Abstract This Letter presents the first observation on interplay between nonlocal transport and neoclassical tearing modes (NTMs) during transient heat events in HL-2A tokamak. The nonlocality is triggered by edge cooling large-scale, inward propagating avalanches. These lead to a locally enhanced pressure gradient at q = 3/2 (or 2/1) rational surface hence onset of NTM relatively low β plasmas ( N < 1). NTM, return, regulates truncation avalanches local sheared toroidal flows which...
At least the far scrape-off layer of magnetically confined fusion plasmas transport is intermittent and non-diffusive as observed by appearance plasma filaments. Transport codes using effective diffusion coefficients are still main workhorse investigating divertor regions. An perpendicular coefficient for filamentary dominated in motivated telegraph equation, describing an exponentially decaying correlated random walk. On short time scales, equation describes ballistic structures with a...
We compare various diagnostics characterizing an ASDEX Upgrade upper single-null discharge to EMC3-EIRENE simulations now including volumetric recombination and main chamber plasma-wall interaction but not yet drifts. The is in a small-ELM regime approaching detachment due density ramp nitrogen seeding. Time/ELM averaged upstream density, electron ion temperature measurements as well downstream saturation current, power flux match the simulation within error bars before after reaching...
The bidirectional space charge effects in photon-enhanced thermionic emission (PETE) devices are investigated systematically. First, we precisely determine the carrier concentrations and cathode temperatures by taking into account electron recycling effect, energy balance constraints, arising from concurrent discharge of anode. Next, analyze impact critical parameters, including anode properties operating conditions, on barrier distribution overall performance device. results demonstrate...
A new high-frequency magnetic diagnostic system is designed, installed, and calibrated in the Sino-United Spherical Tokamak (SUNIST) to investigate Alfvén waves (AWs). The consists of a fixed toroidal array movable radial probes (HFMPs) with 21 60 probes, respectively. Based on method vacuum enameled wire wound ceramic bobbins, located as near possible plasma carefully shielded reduce attenuation field. Meanwhile, by using technology commercial chip inductors mounted printed circuit boards,...
The type of edge turbulence transition from resistive ballooning modes (RBM) to drift-type ion temperature gradient (ITG) has been observed in the gas puffing modulation experiments and also simulations at HL-2A tokamak. experimental evidence on RMB ITG characteristics is given by Langmuir probe Doppler reflectometry data. In low region (Te < 80 eV), variation intensity phase with that parallel resistivity, consistent RBM features. However, high > enhanced increasing reduction implying a...
ASDEX Upgrade is preparing a hardware modification of its upper divertor in order to study alternative configurations, like the X-divertor (XD) and snowflake (SF), that are discussed as possible solution for power exhaust problem. Experiments characterizing current single-null (SN) configuration before during detachment were carried out recently interpreted by EMC3-EIRENE (Lunt et al., 2020) now including volumetric recombination. In continuation these studies we here report on further...
ASDEX Upgrade is planning the installation of a pair in-vessel coils in order to study alternative divertor configurations, like an X-divertor (XD) or Snowflake (SF) machine with high heating power compared its size. Two designs for technical realization these are currently proposed, one including z-shaped joints and single spiral conductor. The magnetic fields produced by conductors intrinsically have non-axisymmetric component. In particular XD configuration, where very shallow field line...
Abstract The highly radiating nitrogen-seeded H-mode plasmas in unfavorable B T has been characterized the ASDEX Upgrade tokamak (AUG). Three levels of nitrogen puffing rates have injected into a fully detached plasma, which is run lower single null configuration with ion <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>B</mml:mi> <mml:mo>×</mml:mo> <mml:mi mathvariant="normal">∇</mml:mi> </mml:mrow> </mml:math> drift away from X-point. A cold (...
In this paper, we simulate the function of hot-carrier photocatalysts (HCPCs) with quantum well and dot energy-selective contacts (ESCs) in water-splitting reaction. The transport equations for these ESCs are derived by using ballistic theory. results indicate that thermalization loss from non-ideal is a primary factor diminishing efficiency HCPCs. performance HCPCs can be enhanced optimizing position width extraction energy. Notably, demonstrate superior compared to those ESCs.
According to the mechanism of nearly degeneration four-wave mixing that occurs in a sufficiently nonlinear resonant gaseous medium caused by phase-modulated laser beam, electromagnetism excitation and dynamic evolvement modulation transfer spectroscopy(MTS) technique is studied theoretically, then mathematic models dispersion spectrum absorption MTS are established too. The results show when frequency signal source equal 0.72 times linewidth line approximatively, intensity reaches maximum...