scholarly journals The on-axis magnetic well and Mercier's criterion for arbitrary stellarator geometries

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
P. Kim ◽  
R. Jorge ◽  
W. Dorland
Keyword(s):  
Magnetic Field ◽  
Original Work ◽  
Three Dimensional ◽  
Radial Distance ◽  
Analytical Form ◽  
One Dimensional ◽  
Modern Notation ◽  
Magnetic Well ◽  
First Time ◽  
Dimensional Integral

A simplified analytical form of the on-axis magnetic well and Mercier's criterion for interchange instabilities for arbitrary three-dimensional magnetic field geometries is derived. For this purpose, a near-axis expansion based on a direct coordinate approach is used by expressing the toroidal magnetic flux in terms of powers of the radial distance to the magnetic axis. For the first time, the magnetic well and Mercier's criterion are then written as a one-dimensional integral with respect to the axis arclength. When compared with the original work of Mercier, the derivation here is presented using modern notation and in a more streamlined manner that highlights essential steps. Finally, these expressions are verified numerically using several quasisymmetric and non-quasisymmetric stellarator configurations including Wendelstein 7-X.

Hybrid-Vlasov modelling of three-dimensional dayside magnetopause reconnection

2021 ◽  
Author(s):  
Yann Pfau-Kempf ◽  
Minna Palmroth ◽  
Andreas Johlander ◽  
Lucile Turc ◽  
Markku Alho ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Three Dimensional ◽  
Meridional Plane ◽  
Kinetic Behavior ◽  
Dayside Magnetopause ◽  
Field Junction ◽  
First Time ◽  
Kinetic Instabilities ◽  
Magnetopause Reconnection

<p>Dayside magnetic reconnection at the magnetopause, which is a major driver of space weather, is studied for the first time in a three-dimensional (3D) realistic setup using the Vlasiator hybrid-Vlasov kinetic model. A noon–midnight meridional plane simulation is extended in the dawn–dusk direction to cover 7 Earth radii. The southward interplanetary magnetic field causes magnetic reconnection to occur at the subsolar magnetopause. Perturbations arising from kinetic instabilities in the magnetosheath appear to modulate the reconnection. Its characteristics are consistent with multiple, bursty, and patchy magnetopause reconnection. It is shown that the kinetic behavior of the plasma, as simulated by the model, has consequences on the applicability of methods such as the four-field junction to identify and analyse magnetic reconnection in 3D kinetic simulations.</p>

scholarly journals Magnetohydrodynamic evolution of magnetic skeletons

2007 ◽  
Vol 463 (2080) ◽  
pp. 1097-1115 ◽  
Author(s):  
Andrew L Haynes ◽  
Clare E Parnell ◽  
Klaus Galsgaard ◽  
Eric R Priest
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Three Dimensional ◽  
Heating Process ◽  
Initial State ◽  
Fundamental Building Block ◽  
New Type ◽  
Field Lines ◽  
First Time ◽  
The Magnetic Field

The heating of the solar corona is probably due to reconnection of the highly complex magnetic field that threads throughout its volume. We have run a numerical experiment of an elementary interaction between the magnetic field of two photospheric sources in an overlying field that represents a fundamental building block of the coronal heating process. The key to explaining where, how and how much energy is released during such an interaction is to calculate the resulting evolution of the magnetic skeleton. A skeleton is essentially the web of magnetic flux surfaces (called separatrix surfaces) that separate the coronal volume into topologically distinct parts. For the first time, the skeleton of the magnetic field in a three-dimensional numerical magnetohydrodynamic experiment is calculated and carefully analysed, as are the ways in which it bifurcates into different topologies. A change in topology normally changes the number of magnetic reconnection sites. In our experiment, the magnetic field evolves through a total of six distinct topologies. Initially, no magnetic flux joins the two sources. Then, a new type of bifurcation, called a global double-separator bifurcation , takes place. This bifurcation is probably one of the main ways in which new separators are created in the corona (separators are field lines at which three-dimensional reconnection takes place). This is the first of five bifurcations in which the skeleton becomes progressively more complex before simplifying. Surprisingly, for such a simple initial state, at the peak of complexity there are five separators and eight flux domains present.

Ballooning Modes in Three-dimensional MHD Equilibria with Shear

1978 ◽  
Vol 33 (7) ◽  
pp. 789-791 ◽  
Author(s):  
D. Correa-Restrepo
Keyword(s):  
Magnetic Field ◽  
Eigenvalue Problem ◽  
Field Line ◽  
Magnetic Field Line ◽  
Three Dimensional ◽  
One Dimensional ◽  
Ideal Mhd ◽  
Mhd Equilibria

Stability with respect to ballooning modes in arbitrary, three-dimensional, ideal MHD equilibria with shear is studied. The destabilizing perturbations considered here have finite gradients along the field and are localized around a closed magnetic field line, the localization being weaker on the surface than transversally to it. This kind of localization allows the problem of stability to be reduced to the solution of a one-dimensional eigenvalue problem.

2,3-Dihydro-7,8-dihydroxy-3-[(4-methoxyphenyl)methylene]-4H-1-benzopyran-4-one

2006 ◽  
Vol 62 (4) ◽  
pp. o1254-o1256 ◽  
Author(s):  
Suchada Chantrapromma ◽  
Sompong Boonsri ◽  
Hoong-Kun Fun ◽  
Shazia Anjum ◽  
Akkharawit Kanjana-opas
Keyword(s):  
Hydrogen Bonds ◽  
Intermolecular Interactions ◽  
Title Compound ◽  
Three Dimensional ◽  
Molecular Network ◽  
Pyran Ring ◽  
Intramolecular Hydrogen Bonds ◽  
One Dimensional ◽  
Intramolecular Hydrogen ◽  
First Time

The title compound, also known as intricatinol, C17H14O5, is a homoisoflavanoid that was isolated for the first time from the twigs and stems of Caesalpinia digyna Rottler. The pyran ring is in an envelope form. O—H...O intramolecular hydrogen bonds are observed. Symmetry-related molecules are linked via O—H...O intermolecular interactions to form infinite one-dimensional chains. These chains are interconnected to form a three-dimensional molecular network.

Parametric instability in the expanding solar wind

2021 ◽  
Author(s):  
Andrea Verdini ◽  
Roland Grappin ◽  
Francesco Malara ◽  
Leonardo Primavera ◽  
Luca Del Zanna
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Parametric Instability ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Total Magnetic Field ◽  
One Dimensional ◽  
Preliminary Results ◽  
Dimensional Spectrum ◽  
N Wave

<p>Recent measurments of Parker Solar Probe show that alfvenic fluctuations in the solar wind often appear in the form of swithcback with constant total magnetic field. Our aim is to understand if and how such fluctuations can contribute to the heating or acceleration of the solar wind, via the Parametric Instability. The intability of one dimensional Alfvénic fluctuations has been extensively studied in both homogenoeus plasma and in the expanding solar wind, less so for the two-dimensional case which is closer to expected three-dimensional nature of switchbacks. In this work we study under which condition an Alfvén wave with a two dimensional spectrum (as introduced in Primavera et al ApJ 2019) can decay in the expanding solar wind and we will present preliminary results.</p>

Three‐dimensional transient electromagnetic responses for a grounded source

Geophysics ◽  
1986 ◽  
Vol 51 (11) ◽  
pp. 2117-2130 ◽  
Author(s):  
Brian M. Gunderson ◽  
Gregory A. Newman ◽  
Gerald W. Hohmann
Keyword(s):  
Magnetic Field ◽  
Half Space ◽  
Time Derivative ◽  
Three Dimensional ◽  
The Body ◽  
Vertical Magnetic Field ◽  
Horizontal Magnetic Field ◽  
One Dimensional ◽  
Transient Electromagnetic ◽  
Electromagnetic Responses

When the current in a grounded wire is terminated abruptly, currents immediately flow in the Earth to preserve the magnetic field. Initially the current is concentrated near the wire, with a broad zone of return currents below. The electric field maximum broadens and moves downward with time. Currents are channeled into a conductive three‐dimensional body, resulting in anomalous magnetic fields. At early times, when the return currents are channeled into the body, the vertical magnetic field is less than the half‐space field on the far side of the body but is greater than the half‐space field between the source and the body. Later the current in the body reverses; the vertical field is enhanced on the far side of the body and decreased between the source and the body. The horizontal magnetic field has a well‐defined maximum directly over the body at late times, and is a better indicator of the position of the body. The vertical magnetic field and its time derivative change sign with time at receiver locations near the source if a three‐dimensional body is present. These sign reversals present serious problems for one‐dimensional inversion, because decay curves for a layered earth do not change sign. At positions away from the source, the decay curves exhibit no sign reversals—only decreases and enhancements relative to one‐dimensional decay curves. In such cases one‐dimensional inversions may provide useful information, but they are likely to result in fictitious layers and erroneous interpretations.

Synthesis and physical properties of quasi-one-dimensional magnetic material Ca3LiRuO6

2015 ◽  
Vol 08 (04) ◽  
pp. 1550039 ◽  
Author(s):  
Dapeng Wu ◽  
Yang Qi
Keyword(s):  
Single Crystals ◽  
Magnetic Order ◽  
Three Dimensional ◽  
Complex Nature ◽  
Crystallographic Structure ◽  
Flux Method ◽  
Weiss Temperature ◽  
One Dimensional ◽  
Measurement Results ◽  
First Time

Ca 3 LiRuO 6 single crystals were grown using the flux method, magnetic properties measurement results along different directions of needle-like single crystals are reported for the first time and show Ca 3 LiRuO 6 occurs a paramagnetic (PM)-weak ferromagnetic (FM) transition at a temperature Tc = 120 K , also the magnetic moment aligns in the ab plane. Although Ca 3 LiRuO 6 is characterized by one-dimensional configuration in crystallographic structure, it has three-dimensional (3D) magnetic order, the value of Tc is far below the magnitude of Curie–Weiss temperature. Θcw ≈ -306 K indicates complex nature of the magnetism is in this compound.

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