Comparison of the influence of 2D and 3D geometry of the main chamber on plasma parameters in the SOL of ASDEX Upgrade

2021 ◽  
Author(s):  
Lennart Bock ◽  
Dominik Brida ◽  
Michael Faitsch ◽  
Klaus Schmid ◽  
Tilmann Lunt
Keyword(s):  
Plasma Flow ◽  
Neutral Particle ◽  
3D Structure ◽  
Main Chamber ◽  
Plasma Parameters ◽  
Simulation Code ◽  
Particle Distributions ◽  
Low Field ◽  
3D Geometry ◽  
Wall Geometry

Abstract In this paper the influence of toroidally asymmetric wall features on plasma solutions for ASDEX Upgrade is investigated by using the 3D scrape-off-layer simulation code EMC3-EIRENE. A comparison of simulation results in a 2D case with a toroidally symmetric first wall and divertor and a 3D case that differs from the 2D setup by including the 3D structure of the poloidal rib-limiters on the low field side of ASDEX Upgrade, highlights notable differences in the main chamber neutral particle distributions, ionisation sources and plasma flow patterns. Both neutral particle distribution and ionisation sources extend poloidally further upwards at the outer mid-plane in the 3D case and the plasma flow is globally influenced by the 3D wall features. Both simulations are conducted with identical input parameters to isolate the influence of wall geometry from other factors. By analysing the transport of neutrals from different poloidal locations it was possible to explain the observed discrepancies by different transport paths for recycled neutrals from the divertor region, only accessible in the 3D version of the wall geometry. Together with observed differences in fall-off lengths for plasma flow and electron temperature at the outer mid-plane, presented results are of key importance for interpreting global impurity migration experiments.

scholarly journals Three-dimensional multispecies hybrid simulation of Titan's highly variable plasma environment

2007 ◽  
Vol 25 (1) ◽  
pp. 117-144 ◽  
Author(s):  
S. Simon ◽  
A. Boesswetter ◽  
T. Bagdonat ◽  
U. Motschmann ◽  
J. Schuele
Keyword(s):  
Plasma Flow ◽  
Flow Direction ◽  
Three Dimensional ◽  
Hybrid Simulation ◽  
Slight Modification ◽  
Magnetospheric Plasma ◽  
Particle Model ◽  
Tail Region ◽  
Simulation Code ◽  
Ion Species

Abstract. The interaction between Titan's ionosphere and the Saturnian magnetospheric plasma flow has been studied by means of a three-dimensional (3-D) hybrid simulation code. In the hybrid model, the electrons form a mass-less, charge-neutralizing fluid, whereas a completely kinetic approach is retained to describe ion dynamics. The model includes up to three ionospheric and two magnetospheric ion species. The interaction gives rise to a pronounced magnetic draping pattern and an ionospheric tail that is highly asymmetric with respect to the direction of the convective electric field. Due to the dependence of the ion gyroradii on the ion mass, ions of different masses become spatially dispersed in the tail region. Therefore, Titan's ionospheric tail may be considered a mass-spectrometer, allowing to distinguish between ion species of different masses. The kinetic nature of this effect is emphasized by comparing the simulation with the results obtained from a simple analytical test-particle model of the pick-up process. Besides, the results clearly illustrate the necessity of taking into account the multi-species nature of the magnetospheric plasma flow in the vicinity of Titan. On the one hand, heavy magnetospheric particles, such as atomic Nitrogen or Oxygen, experience only a slight modification of their flow pattern. On the other hand, light ionospheric ions, e.g. atomic Hydrogen, are clearly deflected around the obstacle, yielding a widening of the magnetic draping pattern perpendicular to the flow direction. The simulation results clearly indicate that the nature of this interaction process, especially the formation of sharply pronounced plasma boundaries in the vicinity of Titan, is extremely sensitive to both the temperature of the magnetospheric ions and the orientation of Titan's dayside ionosphere with respect to the corotating magnetospheric plasma flow.

scholarly journals Effect of the gas puff location on the divertor plasma properties in COMPASS tokamak

2020 ◽  
Vol 1492 (1) ◽  
pp. 012003
Author(s):  
M Dimitrova ◽  
M Tomes ◽  
Tsv Popov ◽  
R Dejarnac ◽  
J Stockel ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Vacuum Chamber ◽  
Plasma Potential ◽  
Saturation Current ◽  
Langmuir Probes ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Low Field ◽  
Saturation Current Density ◽  
Deuterium Gas

Abstract Langmuir probes are used to study the plasma parameters in the divertor during deuterium gas puff injection on the high- (HFS) or low-field sides (LFS). The probe data were processed to evaluate the plasma potential and the electron temperatures and densities. A difference was found in the plasma parameters depending on the gas puff location. In the case of a gas puff on the LFS, the plasma parameters changed vastly, mainly in the inner divertor – the plasma potential, the ion saturation-current density and the electron temperature dropped. After the gas puff, the electron temperature changed from 10-15 eV down to within the 5-9 eV range. As a result, the parallel heat-flux density decreased. At the same time, in the outer divertor the plasma parameters remained the same. We thus concluded that using a gas puff on the LFS will facilitate reaching a detachment regime by increasing the density of puffed neutrals. When the deuterium gas puff was on the HFS, the plasma parameters in the divertor region remained almost the same before and during the puff. The electron temperature decreased with just few eV as a result of the increased amount of gas in the vacuum chamber.

scholarly journals Plasma environment of Titan: a 3-D hybrid simulation study

2006 ◽  
Vol 24 (3) ◽  
pp. 1113-1135 ◽  
Author(s):  
S. Simon ◽  
A. Bößwetter ◽  
T. Bagdonat ◽  
U. Motschmann ◽  
K.-H. Glassmeier
Keyword(s):  
Plasma Flow ◽  
Molecular Nitrogen ◽  
Hybrid Simulation ◽  
Spherical Geometry ◽  
Magnetospheric Plasma ◽  
Simulation Code ◽  
Plasma Environment ◽  
Ion Production ◽  
Solar Uv ◽  
Magnetohydrodynamic Models

Abstract. Titan possesses a dense atmosphere, consisting mainly of molecular nitrogen. Titan's orbit is located within the Saturnian magnetosphere most of the time, where the corotating plasma flow is super-Alfvénic, yet subsonic and submagnetosonic. Since Titan does not possess a significant intrinsic magnetic field, the incident plasma interacts directly with the atmosphere and ionosphere. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's interaction with the corotating magnetospheric plasma flow. For this reason, Titan's plasma environment has been studied by using a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The calculations are performed on a curvilinear simulation grid which is adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation; hence, the local ion production rate depends on the solar zenith angle. Because the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. In general, the mechanism giving rise to these structures exhibits similarities to the interaction of the ionospheres of Mars and Venus with the supersonic solar wind. The simulation results are in agreement with data from recent Cassini flybys.

Solving the 3D structure of metal nanoparticles

2007 ◽  
Vol 222 (11/2007) ◽  
Author(s):  
Anatoly Frenkel
Keyword(s):  
Metal Nanoparticles ◽  
Short Range ◽  
Short Range Order ◽  
3D Structure ◽  
Three Dimensional ◽  
X Ray ◽  
Particle Distributions ◽  
Structure Of Metal ◽  
X Ray Absorption

We discuss methods of Extended X-ray Absorption Fine-Structure (EXAFS) analysis that provide three-dimensional structural characterization of metal nanoparticles, both mono- and bi-metallic. For the bimetallic alloys, we use short range order measurements to discriminate between random and non-random inter-particle distributions of atoms. We also discuss the application of EXAFS to heterogeneous nanoparticle systems.

Spatially resolved measurements of energetic neutral particle distributions in the Large Helical Device

2003 ◽  
Vol 74 (3) ◽  
pp. 1873-1877 ◽  
Author(s):  
J. F. Lyon ◽  
P. R. Goncharov ◽  
S. Murakami ◽  
T. Ozaki ◽  
D. E. Greenwood ◽  
...  
Keyword(s):  
Neutral Particle ◽  
Particle Distributions ◽  
Spatially Resolved

scholarly journals Recent Progress in Birdcage RF Coil Technology for MRI System

Diagnostics ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1017
Author(s):  
Sheikh Faisal Ahmad ◽  
Young Cheol Kim ◽  
Ick Chang Choi ◽  
Hyun Deok Kim
Keyword(s):  
Magnetic Resonance ◽  
Recent Progress ◽  
3D Structure ◽  
Larmor Frequency ◽  
High Sensitivity ◽  
Transverse Magnetic ◽  
Rf Coil ◽  
Low Field ◽  
Volume Of Interest ◽  
Magnetic Resonance Imaging Mri

The radio frequency (RF) coil is one of the key components of the magnetic resonance imaging (MRI) system. It has a significant impact on the performance of the nuclear magnetic resonance (NMR) detection. Among numerous practical designs of RF coils for NMR imaging, the birdcage RF coil is the most popular choice from low field to ultra-high field MRI systems. In the transmission mode, it can establish a strong and homogeneous transverse magnetic field B1 for any element at its Larmor frequency. Similarly, in the reception mode, it exhibits extremely high sensitivity for the detection of even faint NMR signals from the volume of interest. Despite the sophisticated 3D structure of the birdcage coil, the developments in the design, analysis, and implementation technologies during the past decade have rendered the development of the birdcage coils quite reasonable. This article provides a detailed review of the recent progress in the birdcage RF coil technology for the MRI system.

scholarly journals Magnetosheath plasma flow model around Mercury

2021 ◽  
Author(s):  
Daniel Schmid ◽  
Ferdinand Plaschke ◽  
Yasuhito Narita ◽  
Martin Volwerk ◽  
Rumi Nakamura ◽  
...  
Keyword(s):  
Solar Wind ◽  
Plasma Flow ◽  
Flow Model ◽  
Outer Boundary ◽  
Solar Wind Plasma ◽  
Bow Shock ◽  
Plasma Parameters ◽  
Upstream Solar Wind ◽  
Planetary Magnetic Field ◽  
Spacecraft Location

Abstract. The magnetosheath is defined as the plasma region between the bow shock, where the super-magnetosonic solar wind plasma is decelerated and heated, and the outer boundary of the intrinsic planetary magnetic field, the so called magnetopause. Based on the Soucek-Escoubet magnetosheath flow model at Earth, we present the first analytical magnetosheath plasma flow model for Mercury. It can be used to estimate the plasma flow magnitude and direction at any given point in the magnetosheath exclusively on the basis of the plasma parameters of the upstream solar wind. The aim of this paper is to provide a tool to back-trace the magnetosheath plasma flow between multiple observation points or from a given spacecraft location to the bow shock.

2D quasi-planar or 3D structures? A comparison between CrBn(n = 2 − 10) wheel-like clusters and their corresponding 3D pyramidal clusters, and their hydrogen storage capability

2015 ◽  
Vol 29 (24) ◽  
pp. 1550172 ◽  
Author(s):  
E. K. Yildirim
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Hydrogen Storage ◽  
Density Functional ◽  
3D Structure ◽  
Planar Geometry ◽  
Functional Theory ◽  
Cluster Interaction ◽  
3D Geometry ◽  
Stable Structures

In this study, we investigated stable structures for a transition metal atom–boron (CrB) wheel-like clusters and compared them with their corresponding 3D counterparts by means of density functional theory (DFT). In addition, hydrogen storage capability of the wheel-like system was investigated. All simulations were performed at the B3LYP/TZVP level of theory. We set out a complete route to the formation of CrB wheel-like clusters. Our results showed that, some of the clusters, investigated in this work (CrBn; n = 4, 6, 7, 8), either prefer to be in a 3D geometry rather than 2D quasi-planar or planar geometry. However, hydrogen doping has an interesting effect on both 2D quasi-planar and 3D geometries of this system. Simply it transforms the 3D structure, first, into a 2D quasi-planar, then a planar geometry. Furthermore, our results show that H–cluster interaction is too high for reversible hydrogen storage for these clusters.

Modeling of neutral particle distributions at the L to H transition in DIII-D

1999 ◽  
Vol 266-269 ◽  
pp. 890-895 ◽  
Author(s):  
L.W. Owen ◽  
B.A. Carreras ◽  
R. Maingi ◽  
P.K. Mioduszewski ◽  
T.N. Carlstrom ◽  
...  
Keyword(s):  
Neutral Particle ◽  
Particle Distributions

scholarly journals Direct 2D-to-3D transformation of pen drawings

2021 ◽  
Vol 7 (13) ◽  
pp. eabf3804 ◽  
Author(s):  
Seo Woo Song ◽  
Sumin Lee ◽  
Jun Kyu Choe ◽  
Na-Hyang Kim ◽  
Junwon Kang ◽  
...  
Keyword(s):  
3D Structure ◽  
Fabrication Technology ◽  
3D Objects ◽  
Surface Initiated Polymerization ◽  
Structural Reinforcement ◽  
Roll To Roll ◽  
3D Geometry ◽  
Monomer Solution ◽  
2D Drawing ◽  
2D To 3D

Pen drawing is a method that allows simple, inexpensive, and intuitive two-dimensional (2D) fabrication. To integrate such advantages of pen drawing in fabricating 3D objects, we developed a 3D fabrication technology that can directly transform pen-drawn 2D precursors into 3D geometries. 2D-to-3D transformation of pen drawings is facilitated by surface tension–driven capillary peeling and floating of dried ink film when the drawing is dipped into an aqueous monomer solution. Selective control of the floating and anchoring parts of a 2D precursor allowed the 2D drawing to transform into the designed 3D structure. The transformed 3D geometry can then be fixed by structural reinforcement using surface-initiated polymerization. By transforming simple pen-drawn 2D structures into complex 3D structures, our approach enables freestyle rapid prototyping via pen drawing, as well as mass production of 3D objects via roll-to-roll processing.

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