Preliminary experimental scaling of the helical mirror confinement effectiveness

2020 ◽  
Vol 86 (5) ◽  
Author(s):  
Anton V. Sudnikov ◽  
Aleksey D. Beklemishev ◽  
Anna A. Inzhevatkina ◽  
Ivan A. Ivanov ◽  
Vladimir V. Postupaev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Active Control ◽  
Plasma Density ◽  
Plasma Flow ◽  
Nuclear Physics ◽  
Suppression Ratio ◽  
Experimental Results ◽  
Budker Institute ◽  
The Magnetic Field ◽  
Helical Field

The paper presents experimental results from the SMOLA device that is the first facility with a helical mirror section of the magnetic field. This device is built in the Budker Institute of Nuclear Physics for the verification of the helical mirror confinement idea that is the recently introduced technique of the active control of axial losses from a confinement zone. Theory predicts that with rotating plasma, a helical mirror will provide suppression of the axial plasma flow and, simultaneously, density pinching to the axis. Experiments demonstrated that plasma density at the exit from the transport section is suppressed with activation of the helical field, the effect is significant and highly reproducible. The most pronounced effect is observed on the plasma periphery, where the mirror ratio is the highest. The integral suppression ratio reaches 2–2.5 in the discussed experiments. Experimental results are compared with simplified theoretical estimates. The integral suppression ratio matches the simple theoretical estimates even if the transversal diffusion is neglected.

Localization of the magnetic field in a plasma flow in laboratory simulations of astrophysical jets at the KPF-4-PHOENIX installation

2017 ◽  
Vol 61 (9) ◽  
pp. 775-782 ◽  
Author(s):  
K. N. Mitrofanov ◽  
S. S. Anan’ev ◽  
D. A. Voitenko ◽  
V. I. Krauz ◽  
G. I. Astapenko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Astrophysical Jets ◽  
Laboratory Simulations ◽  
The Magnetic Field

Experimental Research on the Magnetic Field Sensitive Polymeric Actuator

2011 ◽  
Vol 287-290 ◽  
pp. 603-607
Author(s):  
Chun Lin Xia ◽  
Yang Fang Wu ◽  
Qian Qian Lu
Keyword(s):  
Magnetic Field ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Energy Conversion ◽  
Experimental Research ◽  
Experimental Results ◽  
Deformation Characteristics ◽  
Analysis Software ◽  
Element Analysis ◽  
The Magnetic Field

Using domestic MFSP membrane as a medium of energy conversion, a kind of MFSP actuator was designed. The dedicated test equipment was constructed for experimental research, and the experimental results were given. The strip and circular MSFP membrane were analyzed qualitatively to obtain the deformation characteristics of membrane by finite element analysis software.

Influence of the magnetic field of stellar wind on hot jupiter’s envelopes

2019 ◽  
Vol 15 (S354) ◽  
pp. 268-279
Author(s):  
Dmitry V. Bisikalo ◽  
Andrey G. Zhilkin
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Coronal Mass Ejections ◽  
Stellar Wind ◽  
Roche Lobe ◽  
Bow Shock ◽  
Hot Jupiters ◽  
The Magnetic Field ◽  
Alfven Velocity ◽  
Hot Jupiter

AbstractHot Jupiters have extended gaseous (ionospheric) envelopes, which extend far beyond the Roche lobe. The envelopes are loosely bound to the planet and, therefore, are strongly influenced by fluctuations of the stellar wind. We show that, since hot Jupiters are close to the parent stars, magnetic field of the stellar wind is an important factor defining the structure of their magnetospheres. For a typical hot Jupiter, velocity of the stellar wind plasma flow around the atmosphere is close to the Alfvén velocity. As a result stellar wind fluctuations, such as coronal mass ejections, can affect the conditions for the formation of a bow shock around a hot Jupiter. This effect can affect observational manifestations of hot Jupiters.

scholarly journals Nonlinear translational symmetric equilibria relevant to the L–H transition

2012 ◽  
Vol 79 (3) ◽  
pp. 257-265 ◽  
Author(s):  
Ap. KUIROUKIDIS ◽  
G. N. THROUMOULOPOULOS
Keyword(s):  
Magnetic Field ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Plasma Flow ◽  
Sufficient Condition ◽  
Sheared Flow ◽  
Equilibrium Configurations ◽  
Shafranov Equation ◽  
The Impact ◽  
The Magnetic Field

AbstractNonlinear z-independent solutions to a generalized Grad–Shafranov equation (GSE) with up to quartic flux terms in the free functions and incompressible plasma flow non-parallel to the magnetic field are constructed quasi-analytically. Through an ansatz, the GSE is transformed to a set of three ordinary differential equations and a constraint for three functions of the coordinate x, in Cartesian coordinates (x,y), which then are solved numerically. Equilibrium configurations for certain values of the integration constants are displayed. Examination of their characteristics in connection with the impact of nonlinearity and sheared flow indicates that these equilibria are consistent with the L–H transition phenomenology. For flows parallel to the magnetic field, one equilibrium corresponding to the H state is potentially stable in the sense that a sufficient condition for linear stability is satisfied in an appreciable part of the plasma while another solution corresponding to the L state does not satisfy the condition. The results indicate that the sheared flow in conjunction with the equilibrium nonlinearity plays a stabilizing role.

Magnetohydrodynamic Equilibria

2020 ◽  
Author(s):  
Thomas Wiegelmann
Keyword(s):  
Magnetic Field ◽  
Boundary Conditions ◽  
Lorentz Force ◽  
Plasma Flow ◽  
Plasma Pressure ◽  
Mhd Equations ◽  
The Sun ◽  
Planetary Magnetospheres ◽  
Mhd Equilibria ◽  
The Magnetic Field

Magnetohydrodynamic equilibria are time-independent solutions of the full magnetohydrodynamic (MHD) equations. An important class are static equilibria without plasma flow. They are described by the magnetohydrostatic equations j×B=∇p+ρ∇Ψ,∇×B=μ0j,∇·B=0. B is the magnetic field, j the electric current density, p the plasma pressure, ρ the mass density, Ψ the gravitational potential, and µ0 the permeability of free space. Under equilibrium conditions, the Lorentz force j×B is compensated by the plasma pressure gradient force and the gravity force. Despite the apparent simplicity of these equations, it is extremely difficult to find exact solutions due to their intrinsic nonlinearity. The problem is greatly simplified for effectively two-dimensional configurations with a translational or axial symmetry. The magnetohydrostatic (MHS) equations can then be transformed into a single nonlinear partial differential equation, the Grad–Shafranov equation. This approach is popular as a first approximation to model, for example, planetary magnetospheres, solar and stellar coronae, and astrophysical and fusion plasmas. For systems without symmetry, one has to solve the full equations in three dimensions, which requires numerically expensive computer programs. Boundary conditions for these systems can often be deduced from measurements. In several astrophysical plasmas (e.g., the solar corona), the magnetic pressure is orders of magnitudes higher than the plasma pressure, which allows a neglect of the plasma pressure in lowest order. If gravity is also negligible, Equation 1 then implies a force-free equilibrium in which the Lorentz force vanishes. Generalizations of MHS equilibria are stationary equilibria including a stationary plasma flow (e.g., stellar winds in astrophysics). It is also possible to compute MHD equilibria in rotating systems (e.g., rotating magnetospheres, rotating stellar coronae) by incorporating the centrifugal force. MHD equilibrium theory is useful for studying physical systems that slowly evolve in time. In this case, while one has an equilibrium at each time step, the configuration changes, often in response to temporal changes of the measured boundary conditions (e.g., the magnetic field of the Sun for modeling the corona) or of external sources (e.g., mass loading in planetary magnetospheres). Finally, MHD equilibria can be used as initial conditions for time-dependent MHD simulations. This article reviews the various analytical solutions and numerical techniques to compute MHD equilibria, as well as applications to the Sun, planetary magnetospheres, space, and laboratory plasmas.

scholarly journals Plasma Flow and Solar Wind Acceleration in Non-Radial Coronal Magnetic Fields

1983 ◽  
Vol 102 ◽  
pp. 473-477
Author(s):  
H. Biernat ◽  
N. Kömle ◽  
H. Rucker
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Plasma Flow ◽  
Coronal Holes ◽  
Expansion Velocity ◽  
The Sun ◽  
Solar Wind Acceleration ◽  
Coronal Magnetic Fields ◽  
Field Lines ◽  
The Magnetic Field

In the vicinity of the Sun — especially above coronal holes — the magnetic field lines show strong non-radial divergence and considerable curvature (see e.g. Kopp and Holzer, 1976; Munro and Jackson, 1977; Ripken, 1977). In the following we study the influence of these characteristics on the expansion velocity of the solar wind.

scholarly journals Observations of vortex-like structure in the cusp-magnetosheath region during northward IMF orientation

2008 ◽  
Vol 26 (11) ◽  
pp. 3375-3387 ◽  
Author(s):  
O. Tkachenko ◽  
J. Šafránková ◽  
Z. Němeček ◽  
J. Šimůnek ◽  
L. Přech
Keyword(s):  
Magnetic Field ◽  
High Altitude ◽  
Plasma Flow ◽  
Alternative Explanation ◽  
Regular Feature ◽  
Hot Plasma ◽  
Large Vortex ◽  
Small Structure ◽  
The Magnetic Field ◽  
Statistical Results

Abstract. Two-point observations made by the Interball spacecraft pair unveiled a presence of a large vortex-like structure filled by slow and heated plasma in the outer cusp during periods of the positive BZ interplanetary magnetic field (IMF) component. We have observed the rotation of the magnetic field and the decrease of its magnitude connected with the presence of a hot plasma population inside the vortex. The structure starts with a clear reversal of the plasma flow caused by reconnection tailward of the cusp that turns a part of the magnetosheath plasma into the cusp. We compare the observations of two spacecraft in detail, discuss the differences between them and suggest the way of a formation such structure. Moreover, the statistical results have confirmed that this phenomenon is probably a regular feature of the high-altitude cusp, however, this relatively small structure cannot be observed too often. The alternative explanation of presented observations as a flapping of the magnetopause is taken into account and discussed.

scholarly journals Rotation of the magnetic field in Earth's magnetosheath by bulk magnetosheath plasma flow

2006 ◽  
Vol 24 (1) ◽  
pp. 339-354 ◽  
Author(s):  
M. Longmore ◽  
S. J. Schwartz ◽  
E. A. Lucek
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Plasma Flow ◽  
Mean Value ◽  
Flow Coupling ◽  
Parker Spiral ◽  
Magnetic Field Model ◽  
Field Lines ◽  
The Magnetic Field

Abstract. Orientations of the observed magnetic field in Earth's dayside magnetosheath are compared with the predicted field line-draping pattern from the Kobel and Flückiger static magnetic field model. A rotation of the overall magnetosheath draping pattern with respect to the model prediction is observed. For an earthward Parker spiral, the sense of the rotation is typically clockwise for northward IMF and anticlockwise for southward IMF. The rotation is consistent with an interpretation which considers the twisting of the magnetic field lines by the bulk plasma flow in the magnetosheath. Histogram distributions describing the differences between the observed and model magnetic field clock angles in the magnetosheath confirm the existence and sense of the rotation. A statistically significant mean value of the IMF rotation in the range 5°-30° is observed in all regions of the magnetosheath, for all IMF directions, although the associated standard deviation implies large uncertainty in the determination of an accurate value for the rotation. We discuss the role of field-flow coupling effects and dayside merging on field line draping in the magnetosheath in view of the evidence presented here and that which has previously been reported by Kaymaz et al. (1992).

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