A5059707608- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Plasma Diagnostics and Applications
- Astro and Planetary Science
- Particle Accelerators and Free-Electron Lasers
- Nuclear reactor physics and engineering
- Spacecraft and Cryogenic Technologies
- Gas Dynamics and Kinetic Theory
- Gyrotron and Vacuum Electronics Research
- Inertial Sensor and Navigation
- Atomic and Molecular Physics
- History and Developments in Astronomy
- Particle physics theoretical and experimental studies
- Adaptive optics and wavefront sensing
- Distributed and Parallel Computing Systems
- Particle Detector Development and Performance
- Magnetic Field Sensors Techniques
Max Planck Institute for Plasma Physics
2013-2024
Max Planck Institute for Plasma Physics - Greifswald
2010-2024
Max Planck Society
2012-2021
Princeton Plasma Physics Laboratory
2020
Max Planck Innovation
2014
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...
An overview is given of physics differences between stellarators and tokamaks, including magnetohydrodynamic equilibrium, stability, fast-ion physics, plasma rotation, neoclassical turbulent transport edge physics. Regarding microinstabilities, it shown that the ordinary, collisionless trapped-electron mode stable in large parts parameter space have been designed so parallel adiabatic invariant decreases with radius. Also, first global, electromagnetic, gyrokinetic stability calculations...
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...
One of the principal goals W7-X stellarator is to demonstrate good confinement energetic ions at finite β. This confinement, however, sensitive magnetic field configuration and thus vulnerable design modifications coil geometry. The collisionless drift orbit losses for 60 keV protons in are studied using ANTS code. Particles this energy range will be produced by neutral beam injection (NBI) system being constructed W7-X, particularly important because accurately mimick behaviour 3.5 MeV...
A novel, compact, quasi-axisymmetric configuration is presented which exhibits low fast-particle losses and stable to ideal MHD instabilities. The design has loss rates below 8\% for flux surfaces within the half-radius, shown have an MHD-stability limit of a normalised pressure $\langle\beta\rangle=3\%$ where $\langle\beta\rangle$ volume averaged. at various plasma betas currents as calculated using SPEC equilibrium code are presented. Neoclassical transport coefficients be similar...
Quasi-symmetry can greatly improve the confinement of energetic particles and thermal plasma in a stellarator. The magnetic field quasi-symmetric stellarator at high pressure is significantly affected by bootstrap current, but computational cost accurate calculations has precluded use inside optimization. Here, new efficient method demonstrated for optimization configurations such that current profile consistent with geometry. approach based on fact all neoclassical phenomena quasi-symmetry...
The stellarator is a type of fusion energy device that—if properly designed—could provide clean, safe, and abundant to the grid. To generate this energy, must keep hot mixture charged particles (known as plasma) sufficiently confined by using fully shaped magnetic field. If achieved, heat from reactions within plasma can be harvested energy. We present novel method for designing reactor-relevant fields, which combine several key physical properties. These include stability, excellent...
Disruptions in large tokamaks can lead to the generation of a relativistic runaway electron beam that may cause serious damage first wall. To mitigate disruption and suppress application resonant magnetic perturbations has been suggested. In this work we investigate effect on confinement electrons by simulating their drift orbits magnetostatic perturbed fields calculating orbit losses for various initial energies perturbation magnitudes. simulations use TEXTOR-like configuration solve...
It is well known that optimisation of the MHD equilibrium stellarators can have great influence on performance and hence a significant effect potential as power plants.
Stellarator configurations with reactor relevant energetic particle losses are constructed by simultaneously optimizing for quasisymmetry and an analytically derived metric ( $\unicode[STIX]{x1D6E4}_{c}$ ), which attempts to align contours of the second adiabatic invariant, $J_{\Vert }$ magnetic surfaces. Results show that this optimization scheme it is possible generate quasihelically symmetric equilibria on scale ARIES-CS completely eliminate all collisionless alpha within normalized...
The MFBE procedure developed by Strumberger (1997 Nucl. Fusion 37 19) is used to provide an improved starting point for free boundary equilibrium computations in the case of W7-X (Nührenberg and Zille 1986 Phys. Lett. A 114 129) using Princeton iterative solver (PIES) code (Reiman Greenside Comput. Commun. 43 157). Transferring consistent field found variational moments (VMEC) (Hirshmann Whitson 1983 Fluids 26 3553) extended coordinate system VMORPH code, a safe margin between plasma PIES...
Abstract This work presents the physics design for a simple quasi‐axially symmetric stellarator. A plasma configuration described by modest number of Fourier coefficients was found to establish this symmetry with good accuracy. The low rotational transform results in relatively coil set exhibiting curvatures and comfortable clearance between adjacent coils. As another consequence, maximum achievable pressure will be limited about 0.5%. An experiment along lines proposed would allow an...
It is shown that the magnetic-field coils of a stellarator can, at least in principle, be substantially simplified by use permanent magnets. Such magnets cannot create toroidal magnetic flux, but they can used to shape plasma and thus poloidal flux rotational transform, thereby easing requirements on coils. As an example, quasiaxisymmetric configuration constructed with only 8 circular (all identical)
Abstract The reduction of neoclassical energy transport in stellarators has traditionally focused on optimizing magnetic fields for small values of&#xD;`effective helical ripple' --- \epsilon_{eff}, the geometric factor associated with electron 1/\nu and relying radial electric field, E_r, needed to maintain ambipolarity plasma, simultaneously diminish ion losses a tolerable level. As one must generally expect E_r < 0, such strategy drawback reactor operation, however, as negative...
Abstract The CN-H1 stellarator is a HELIAC, and re-build with partly renewed coils at the University of South China. We calculate set equilibria varying helical current compute their Alfvén sound excitation spectrum. With plot density frequencies, we provide proxy for continuum damping visibility excitations in diagnostics. Furthermore, explore importance magnetic islands spectrum device. Thereby expand numerical tool to include modifications due along so called slow-sound approximation....
Disruptions in large tokamaks can lead to the generation of a relativistic runaway electron beam that may cause serious damage first wall. To suppress application resonant magnetic perturbations (RMPs) has been suggested. In this work we investigate effect RMPs on confinement electrons by simulating their drift orbits magnetostatic perturbed fields and calculating transport orbit losses for various initial energies different perturbation configurations. simulations model ITER RMP...
A new optimized quasihelically symmetric configuration is described that has the desir-able properties of improved energetic particle confinement, reduced turbulent transportby 3D shaping, and non-resonant divertor capabilities. The presented in thispaper explicitly for quasihelical symmetry, confinement,neoclassical stability near axis. Post optimization, configurationwas evaluated its performance with regard to transport, idealmagnetohydrodynamic (MHD) at various values plasma pressure,...
Nine stellarator configurations, three quasiaxisymmetric, quasihelically symmetric and non-quasisymmetric are scaled to ARIES-CS size analyzed for energetic particle content. The best performing configurations with regard confinement also perform the on neoclassical {\Gamma}c metric, which attempts align contours of second adiabatic invariant flux surfaces. Quasisymmetric that simultaneously well quasisymmetry have overall confinement, collisional losses under 3%, approaching performance...
Abstract The first stellarator design was a simple tube of plasma twisted and closed on itself in the form figure-8. line such devices, however, quickly ended over concerns related to stability. We revisit figure-8 concept, re-imagined as modern optimized stellarator, find potential for high degree stability, well exceptionally construction. In particular, that we admits planar coils, is quasi-isodynamic have this property. Our work made possible by recent theoretical progress near-axis...
Key physics issues in the design of a high- quasi-axisymmetric stellarator configuration are discussed. The goal study is compact with aspect ratio comparable to that tokamaks and good transport stability properties. Quasi-axisymmetry has been used provide drift trajectories. Ballooning stabilization accomplished by strong axisymmetric shaping, yielding whose core second regime for ballooning modes. A combination externally generated shear non-axisymmetric corrugation plasma boundary...
High-beta, low-aspect-ratio (“compact”) stellarators are promising solutions to the problem of developing a magnetic plasma configuration for fusion power plants that can be sustained in steady state without disrupting. These concepts combine features and advanced tokamaks have aspect ratios similar those (2–4). They based on computed configurations shaped three dimensions provide desired stability transport properties. Experiments planned as part program develop this concept. A β=4%...
Abstract Configurations deviating from the optimum high‐mirror configuration of W7‐X may show significant bootstrap currents being detrimental for proper island divertor operation. Two basic scenarios to reconcile this are investigated with respect equilibrium, stability and boundary structures. The first scenario freely evolving current realizes operation by adjusting vacuum magnetic field. As evolves on L/R time scale (40s) needs long discharges. second compensates net ECCD keeping...