Observations of Mirror Mode Structures in the Dawn‐side Magnetosphere

2020 ◽  
Author(s):  
M. O. Chandler ◽  
S. J. Schwartz ◽  
L. A. Avanov ◽  
V. N. Coffey ◽  
B. L. Giles ◽  
...  
Keyword(s):  
Mirror Mode

First identification of mirror mode waves in Venus' magnetosheath?

2008 ◽  
Vol 35 (12) ◽  
pp. n/a-n/a ◽  
Author(s):  
M. Volwerk ◽  
T. L. Zhang ◽  
M. Delva ◽  
Z. Vörös ◽  
W. Baumjohann ◽  
...  
Keyword(s):  
Mirror Mode

scholarly journals Magnetic Decreases (MDs) and mirror modes: two different plasma β changing mechanisms

2010 ◽  
Vol 17 (5) ◽  
pp. 467-479 ◽  
Author(s):  
B. T. Tsurutani ◽  
G. S. Lakhina ◽  
O. P. Verkhoglyadova ◽  
E. Echer ◽  
F. L. Guarnieri
Keyword(s):  
Free Energy ◽  
Energetic Particle ◽  
Ponderomotive Force ◽  
Interplanetary Space ◽  
The Other ◽  
Characteristic Scale ◽  
Physical Processes ◽  
Scale Size ◽  
Mirror Mode ◽  
Energetic Particle Transport

Abstract. We discuss two different physical processes that create localized high β plasma regions. One is nonlinear wave-steepening, generating magnetic decreases (MDs) by a ponderomotive force. The other is the mirror instability generating alternating high and low β plasma regions. It is demonstrated that MDs and mirror modes are observationally quite different structures. MDs spatially occur in interplanetary space and mirror modes primarily in planetary magnetosheaths. MDs are characterized by: 1) variable (exponentially decreasing number with increasing) angular changes, 2) variable (exponentially decreasing) thicknesses, and 3) no characteristic inter-event spacings. In sharp contrast, mirror modes are characterized by: 1) little or no angular changes across the structures, 2) a characteristic scale size, and 3) are quasiperiodic in nature. Arguments are presented for the recently observed magnetic dips in the heliosheath being mirror mode structures. The sources of free energy for instability are discussed. Both structures are important for energetic particle transport in astrophysical and heliospheric plasmas.

scholarly journals Modelling of mirror mode structures as propagating slow magnetosonic solitons

2009 ◽  
Vol 27 (12) ◽  
pp. 4379-4389 ◽  
Author(s):  
K. Stasiewicz ◽  
C. Z. Cheng
Keyword(s):  
Numerical Modelling ◽  
Excellent Agreement ◽  
Plasma Flow ◽  
Numerical Solutions ◽  
Small Subset ◽  
Instability Condition ◽  
Magnetic Pulsations ◽  
Fluid Theory ◽  
Mirror Mode ◽  
Two Fluid

Abstract. Cluster measurements in the magnetosheath with spacecraft separations of 2000 km indicate that magnetic pulsations interpreted as mirror mode structures are not frozen in plasma flow, but do propagate with speeds of up to ~50 km/s. Properties of these pulsations are shown to be consistent with propagating slow magnetosonic solitons. By using nonlinear two fluid theory we demonstrate that the well known classical mirror instability condition corresponds to a small subset in a continuum of exponentially varying solutions. With the measured plasma moments we have determined parameters of the polybaric pressure model in the region of occurrence of mirror type structures and applied it to numerical modelling of these structures. In individual cases we obtain excellent agreement between observed mirror mode structures and numerical solutions for magnetosonic solitons.

scholarly journals Nonlinear Alfvén waves, discontinuities, proton perpendicular acceleration, and magnetic holes/decreases in interplanetary space and the magnetosphere: intermediate shocks?

2005 ◽  
Vol 12 (3) ◽  
pp. 321-336 ◽  
Author(s):  
B. T. Tsurutani ◽  
G. S. Lakhina ◽  
J. S. Pickett ◽  
F. L. Guarnieri ◽  
N. Lin ◽  
...  
Keyword(s):  
Interplanetary Space ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Reverse Shock ◽  
Propagating Waves ◽  
Mirror Mode ◽  
Interaction Regions ◽  
Electron Holes ◽  
Proton Cyclotron

Abstract. Alfvén waves, discontinuities, proton perpendicular acceleration and magnetic decreases (MDs) in interplanetary space are shown to be interrelated. Discontinuities are the phase-steepened edges of Alfvén waves. Magnetic decreases are caused by a diamagnetic effect from perpendicularly accelerated (to the magnetic field) protons. The ion acceleration is associated with the dissipation of phase-steepened Alfvén waves, presumably through the Ponderomotive Force. Proton perpendicular heating, through instabilities, lead to the generation of both proton cyclotron waves and mirror mode structures. Electromagnetic and electrostatic electron waves are detected as well. The Alfvén waves are thus found to be both dispersive and dissipative, conditions indicting that they may be intermediate shocks. The resultant "turbulence" created by the Alfvén wave dissipation is quite complex. There are both propagating (waves) and nonpropagating (mirror mode structures and MDs) byproducts. Arguments are presented to indicate that similar processes associated with Alfvén waves are occurring in the magnetosphere. In the magnetosphere, the "turbulence" is even further complicated by the damping of obliquely propagating proton cyclotron waves and the formation of electron holes, a form of solitary waves. Interplanetary Alfvén waves are shown to rapidly phase-steepen at a distance of 1AU from the Sun. A steepening rate of ~35 times per wavelength is indicated by Cluster-ACE measurements. Interplanetary (reverse) shock compression of Alfvén waves is noted to cause the rapid formation of MDs on the sunward side of corotating interaction regions (CIRs). Although much has been learned about the Alfvén wave phase-steepening processfrom space plasma observations, many facets are still not understood. Several of these topics are discussed for the interested researcher. Computer simulations and theoretical developments will be particularly useful in making further progress in this exciting new area.

scholarly journals Magnetometer in-flight offset accuracy for the BepiColombo spacecraft

2020 ◽  
Vol 38 (4) ◽  
pp. 823-832 ◽  
Author(s):  
Daniel Schmid ◽  
Ferdinand Plaschke ◽  
Yasuhito Narita ◽  
Daniel Heyner ◽  
Johannes Z. D. Mieth ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Measurements ◽  
Observation Time ◽  
Space Environment ◽  
Method Performance ◽  
Mode Method ◽  
Magnetometer Data ◽  
Mirror Mode ◽  
Fluctuation Method

Abstract. Recently the two-spacecraft mission BepiColombo launched to explore the plasma and magnetic field environment of Mercury. Both spacecraft, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO, also referred to as Mio), are equipped with fluxgate magnetometers, which have proven to be well-suited to measure the magnetic field in space with high precision. Nevertheless, accurate magnetic field measurements require proper in-flight calibration. In particular the magnetometer offset, which relates relative fluxgate readings into an absolute value, needs to be determined with high accuracy. Usually, the offsets are evaluated from observations of Alfvénic fluctuations in the pristine solar wind, if those are available. An alternative offset determination method, which is based on the observation of highly compressional fluctuations instead of incompressible Alfvénic fluctuations, is the so-called mirror mode technique. To evaluate the method performance in the Hermean environment, we analyze four years of MESSENGER (MErcury Surface, Space ENvironment, GEophysics and Ranging) magnetometer data, which are calibrated by the Alfvénic fluctuation method, and compare it with the accuracy and error of the offsets determined by the mirror mode method in different plasma environments around Mercury. We show that the mirror mode method yields the same offset estimates and thereby confirms its applicability. Furthermore, we evaluate the spacecraft observation time within different regions necessary to obtain reliable offset estimates. Although the lowest percentage of strong compressional fluctuations are observed in the solar wind, this region is most suitable for an accurate offset determination with the mirror mode method. 132 h of solar wind data are sufficient to determine the offset to within 0.5 nT, while thousands of hours are necessary to reach this accuracy in the magnetosheath or within the magnetosphere. We conclude that in the solar wind the mirror mode method might be a good complementary approach to the Alfvénic fluctuation method to determine the (spin-axis) offset of the Mio magnetometer.

scholarly journals Observational support for the electron mirror mode: AMPTE-IRM and Equator-S measurements in the magnetosheath

2018 ◽  
Author(s):  
Rudolf A. Treumann ◽  
Wolfgang Baumjohann
Keyword(s):  
High Temperature ◽  
Collisionless Plasma ◽  
Recent Theory ◽  
Dayside Magnetopause ◽  
Mirror Mode

Abstract. Based on AMPTE-IRM and Equator-S observations in the magnetosheath near the dayside magnetopause, we provide observational support for a recent theory by Noreen et al. (2017) of the contribution of the electron mirror instability to the evolution of mirror modes in the high-temperature anisotropic collisionless plasma of the magnetosheath.

scholarly journals Nonlinear Mirror and Weibel modes: peculiarities of quasi-linear dynamics

2010 ◽  
Vol 28 (12) ◽  
pp. 2161-2167 ◽  
Author(s):  
O. A. Pokhotelov ◽  
R. Z. Sagdeev ◽  
M. A. Balikhin ◽  
V. N. Fedun ◽  
G. I. Dudnikova
Keyword(s):  
Distribution Function ◽  
Mode Coupling ◽  
Nonlinear Evolution ◽  
Particle Interaction ◽  
Velocity Distribution Function ◽  
Larmor Radius ◽  
Initial Stage ◽  
Plasma State ◽  
Bgk Modes ◽  
Mirror Mode

Abstract. A theory for nonlinear evolution of the mirror modes near the instability threshold is developed. It is shown that during initial stage the major instability saturation is provided by the flattening of the velocity distribution function in the vicinity of small parallel ion velocities. The relaxation scenario in this case is accompanied by rapid attenuation of resonant particle interaction which is replaced by a weaker adiabatic interaction with mirror modes. The saturated plasma state can be considered as a magnetic counterpart to electrostatic BGK modes. After quasi-linear saturation a further nonlinear scenario is controlled by the mode coupling effects and nonlinear variation of the ion Larmor radius. Our analytical model is verified by relevant numerical simulations. Test particle and PIC simulations indeed show that it is a modification of distribution function at small parallel velocities that results in fading away of free energy driving the mirror mode. The similarity with resonant Weibel instability is discussed.

scholarly journals Mirror mode structures in the asymmetric Hermean magnetosheath: Hybrid simulations

2013 ◽  
Vol 118 (1) ◽  
pp. 405-417 ◽  
Author(s):  
David Herčík ◽  
Pavel M. Trávníček ◽  
Jay R. Johnson ◽  
Eun-Hwa Kim ◽  
Petr Hellinger
Keyword(s):  
Mirror Mode ◽  
Hybrid Simulations

Magnetic Holes in the Solar Wind and Their Relation to Mirror-Mode Structures

1995 ◽  
pp. 201-204
Author(s):  
D. Winterhalter ◽  
M. Neugebauer ◽  
B. E. Goldstein ◽  
E. J. Smith ◽  
B. T. Tsurutani ◽  
...  
Keyword(s):  
Solar Wind ◽  
Mirror Mode
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