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Showing 1 to 20 of 23 for “"separatrix"”.
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Resonances and Mixing in Confined Time-dependent Stokes Flows: The experiments, Numerics, and Analytics
… Stoke Flows are studied: resonances and separatrix crossings. First, I illustrate that the resonances between different components of the original flow and the perturbation may break the invariant surfaces, paving a way to the large-scale mixing. Theoretical estimations are compared …
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Fast photodiode diagnostic on Alcator C-Mod tokamak to study the plasma edge/SOL structure
… peaks at 30 W/m3/ster at I cm outside the separatrix ( ... 1.05) and drops on both sides of the separatrix.
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The Effect of Persistent Vortices on Boundary Layer Behavior in Turbulent Flow along a Kelvin-Stuart Cat's Eyes Wavy Wall
… boundary layer behavior using a von Karman separatrix shaped wavy wall, and Balle [2], who's results showed laminar wall heat fluxes under stationary vortices using the von Karman wavy wall. Based on Dawson's flow visualization, and following Balle's analogy, the separatrix of a …
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Gravitomagnetic effects in compact binary systems : a study of spin-enhanced orbits around Kerr black holes
… homoclinic set of orbits, which lie close to the separatrix dividing stable and unstable orbits. In this thesis we present a study of the spin-induced evolution of inclined, eccentric Kerr black hole orbits. The evolution of the orbital energy, angular momentum, and Carter constant for such orbits …
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Investigation of the shear layer versus the last closed flux surface on TEXT-upgrade
… reconstructions include the x-points and the separatrix. These magnetic flux surface reconstructions and simultaneous data from several Langmuir probes are used to determine the locations of features in the shear layer, specifically the flux surface where Er=0, and of the last closed flux …
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Design of a cusped field plasma thruster
… improvements (including a flat downstream separatrix) that are aimed at increasing performance. In general, plasma thrusters have applications in satellite trajectory adjustment and deep space probes because of their superior fuel efficiency compared to chemical thrusters.
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Quantification of lower hybrid wave absorption in the edge of the Alcator C-Mod Tokamak
… high degree of toroidal symmetry near the plasma separatrix. This indicates absorption occurs just inside the separatrix, or just outside the separatrix over multiple SOL traversals. Measurements of the poloidal distribution of ionization and recombination in the edge were made using a specially …
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Understanding the Mechanisms that Determine the Edge Electron Density Profile in Tokamaks
… model for tokamak operational boundaries. The separatrix operational space (SepOS) model [Eich & Manz, Nuclear Fusion (2021)] predicts boundaries for the L-H transition, the L-mode density limit, and the ideal MHD ballooning limit in terms of plasma quantities evaluated using separatrix …
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Study of recycling impurity retention in Alcator C-mod
… the core impurity level, where they cross the separatrix into the core and where they leave the core. The modeling reproduces within a factor of 2 the experimentally observed compression of Ar in the divertor of Alcator C-Mod. In addition it was found that under attached conditions recycling at …
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Characterization of low-frequency electric potential oscillations near the edge of a plasma confined by a levitated magnetic dipole
… edge fluctuations at field lines near the separatrix. It spans ninety degrees and has 24 probes mounted on it for total probe tip separation of 6.8cm. Bispectral analysis of the fluctuations show that that an inverse cascade of energy is present at times in LDX. The cascade transfers energy …
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Visible spectroscopic imaging on the Alcator C-Mod tokamak
… was found at the location of the secondary separatrix near the inner wall by using these profiles and a kinetic model of the neutrals. 3) Two-dimensional emissivity profiles of visible continuum (420-430nm) have been measured and found to be an order of magnitude too large when compared to …
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Generation and Optimization of Quadrilateral and Hexahedral Meshes
… and devise a new framework that utilizes separatrix based operations along with local and global operations for structure simplification of planar and surface quadrilateral meshes. We also employ an automated singularity movement technique to further simplify the mesh structure. In …
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Experimental studies of magnetic reconnection in 3D geometries
… respect to the background field produces nested separatrix surfaces consisting of field lines that encircle the null coil a certain number of times. The results are, to the best of our knowledge, original and contain features of relevance to the interaction of the Earth's magnetic field with the …
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Analytic calculations of MHD equilibria and of MHD stability boundaries in fusion plasmas
… in a tokamak and spherical tokamak in which a separatrix moves onto the inner surface of the plasma. In the second part, the reliability of the ideal MHD energy principle in fusion grade plasmas is assessed. Six models are introduced, which are constructed to better describe plasma …
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Edge plasma phenomena in the Alcator C-Mod tokamak measured by high resolution X-ray imaging diagnostics
… it is located significantly closer to the separatrix and is often narrower. Both of these differences increase with the safety factor at the edge, q95 . Thus, there is a significant poloidal asymmetry in the impurity density in the H-mode edge region, which increases with q95 . Therefore, …
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Impurity asymmetries in the pedestal region of the Alcator C-Mod Tokamak
… asymmetry in electron density near the separatrix. In contrast to these H-mode results, plasmas with low boundary electron density gradients, such as L-mode and I-mode, exhibit constant impurity density on a flux surface, even if strong electron temperature gradients are present. …
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Study of molybdenum sources and screening in the Alcator C-Mod tokamak
… the molybdenum gross erosion peaks close to the separatrix, the net erosion peaks further away in the target plate. Three surfaces have been identified spectroscopically in C-Mod to be significant sources of molybdenum: the inner wall, the outer divertor and the antenna protection tiles. The …
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Transport Properties of Divertor Edge Plasmas Measured with Multi-Spectral Imaging
… and particle balance. Values of χ⊥ close to the separatrix (ρ < 1.005), and values of D⊥ were consistent with standard modeling practices. However,χ⊥ measurements sufficiently far into the CFR(ρ > 1.005) exceeded typical modeling assumptions by two orders of magnitude. This implies that boundary …
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Experimental classification of divertor detachment
… the X-point and high densities far away from the separatrix occur. This is a situation which is not described by present day theoretical models. Furthermore, it was shown that the conditions of both the inner and outer divertor are strongly coupled and that the inner divertor even influences the …
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A Study of Reconnection Poleward of the Cusp: Cluster and Polar
… boundary layer region near the magnetic separatrix. We identified specific characteristics and compared them to possible generating mechanisms. The most plausible one was kinetic Alfvén waves. Thus, we have provided observational evidence for the structure of the IDR in poleward of the …
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