scholarly journals Magnetospheric plasma boundaries: a test of the frozen-in magnetic field theorem

2005 ◽  
Vol 23 (7) ◽  
pp. 2565-2578 ◽  
Author(s):  
R. Lundin ◽  
M. Yamauchi ◽  
J.-A. Sauvaud ◽  
A. Balogh
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Flux ◽  
Plasma Physics ◽  
Electric Fields ◽  
Measurement Data ◽  
Space Plasma ◽  
Space Plasma Physics ◽  
Macroscopic System ◽  
Ideal Mhd

Abstract. The notion of frozen-in magnetic field originates from H. Alfvén, the result of a work on electromagnetic-hydrodynamic waves published in 1942. After that, the notion of frozen-in magnetic field, or ideal MHD, has become widely used in space plasma physics. The controversy on the applicability of ideal MHD started in the late 1950s and has continued ever since. The applicability of ideal MHD is particularly interesting in regions where solar wind plasma may cross the magnetopause and access the magnetosphere. It is generally assumed that a macroscopic system can be described by ideal MHD provided that the violations of ideal MHD are sufficiently small-sized near magnetic x-points (magnetic reconnection). On the other hand, localized departure from ideal MHD also enables other processes to take place, such that plasma may cross the separatrix and access neighbouring magnetic flux tubes. It is therefore important to be able to quantify from direct measurements ideal MHD, a task that has turned out to be a major challenge. An obvious test is to compare the perpendicular electric field with the plasma drift, i.e. to test if E=–v×B. Yet another aspect is to rule out the existence of parallel (to B) electric fields. These two tests have been subject to extensive research for decades. However, the ultimate test of the "frozen-in" condition, based on measurement data, is yet to be identified. We combine Cluster CIS-data and FGM-data, estimating the change in magnetic flux (δB/δt) and the curl of plasma –v×B(∇×(v×B)), the terms in the "frozen-in equation". Our test suggests that ideal MHD applies in a macroscopic sense in major parts of the outer magnetosphere, for instance, in the external cusp and in the high-latitude magnetosheath. However, we also find significant departures from ideal MHD, as expected on smaller scales, but also on larger scales, near the cusp and in the magnetosphere-boundary layer. We discuss the importance of these findings. Keywords. Magnetospheric physics (Magnetopause, cusp and boundary layers; Solar wind-magnetosphere interactions) – Space plasma physics

scholarly journals Modelling the solar wind interaction with Mercury by a quasi-neutral hybrid model

2003 ◽  
Vol 21 (11) ◽  
pp. 2133-2145 ◽  
Author(s):  
E. Kallio ◽  
P. Janhunen
Keyword(s):  
Solar Wind ◽  
Plasma Physics ◽  
Hybrid Model ◽  
Space Plasma ◽  
Physical Processes ◽  
Space Plasma Physics ◽  
Solar Wind Interaction ◽  
Plasma Parameters ◽  
Advantages And Disadvantages ◽  
Self Consistent

Abstract. Quasi-neutral hybrid model is a self-consistent modelling approach that includes positively charged particles and an electron fluid. The approach has received an increasing interest in space plasma physics research because it makes it possible to study several plasma physical processes that are difficult or impossible to model by self-consistent fluid models, such as the effects associated with the ions’ finite gyroradius, the velocity difference between different ion species, or the non-Maxwellian velocity distribution function. By now quasi-neutral hybrid models have been used to study the solar wind interaction with the non-magnetised Solar System bodies of Mars, Venus, Titan and comets. Localized, two-dimensional hybrid model runs have also been made to study terrestrial dayside magnetosheath. However, the Hermean plasma environment has not yet been analysed by a global quasi-neutral hybrid model. In this paper we present a new quasi-neutral hybrid model developed to study various processes associated with the Mercury-solar wind interaction. Emphasis is placed on addressing advantages and disadvantages of the approach to study different plasma physical processes near the planet. The basic assumptions of the approach and the algorithms used in the new model are thoroughly presented. Finally, some of the first three-dimensional hybrid model runs made for Mercury are presented. The resulting macroscopic plasma parameters and the morphology of the magnetic field demonstrate the applicability of the new approach to study the Mercury-solar wind interaction globally. In addition, the real advantage of the kinetic hybrid model approach is to study the property of individual ions, and the study clearly demonstrates the large potential of the approach to address these more detailed issues by a quasi-neutral hybrid model in the future.Key words. Magnetospheric physics (planetary magnetospheres; solar wind-magnetosphere interactions) – Space plasma physics (numerical simulation studies)

scholarly journals Disturbance of plasma environment in the vicinity of the Astrid-2 microsatellite

2001 ◽  
Vol 19 (6) ◽  
pp. 655-666 ◽  
Author(s):  
N. Ivchenko ◽  
L. Facciolo ◽  
P. A. Lindqvist ◽  
P. Kekkonen ◽  
B. Holback
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Space Plasma ◽  
Plasma Potential ◽  
Space Plasma Physics ◽  
Plasma Environment ◽  
Density Enhancement ◽  
Instruments And Techniques ◽  
Field Lines ◽  
Plasma Depletion

Abstract. The presence of a satellite disturbs the ambient plasma. The charging of the spacecraft creates a sheath around it, and the motion of the satellite creates a wake disturbance. This modification of the plasma environment introduces difficulties in measuring electric fields and plasma densities using the probe technique. We present a study of the structure of the sheath and wake around the Astrid-2 microsatellite, as observed by the probes of the EMMA and LINDA instruments. Measurements with biased LINDA probes, as well as current sweeps on the EMMA probes, show a density enhancement upstream of the satellite and a plasma depletion behind the satellite. The electric field probes detect disturbances in the plasma potential on magnetic field lines connected to the satellite.Key words. Space plasma physics (spacecraft sheaths, wakes, charging; instruments and techniques)

scholarly journals EMMA - the Electric and Magnetic Monitor of the Aurora on Astrid-2

2004 ◽  
Vol 22 (1) ◽  
pp. 115-123 ◽  
Author(s):  
L. G. Blomberg ◽  
G. T. Marklund ◽  
P.-A. Lindqvist ◽  
F. Primdahl ◽  
P. Brauer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Physics ◽  
Electrical Contact ◽  
Digital Signal ◽  
Space Plasma ◽  
Separation Distance ◽  
Fluxgate Magnetometer ◽  
Space Plasma Physics ◽  
Fluxgate Sensor ◽  
Signal Processors

Abstract. The Astrid-2 mission has dual primary objectives. First, it is an orbiting instrument platform for studying auroral electrodynamics. Second, it is a technology demonstration of the feasibility of using micro-satellites for innovative space plasma physics research. The EMMA instrument, which we discuss in the present paper, is designed to provide simultaneous sampling of two electric and three magnetic field components up to about 1kHz. The spin plane components of the electric field are measured by two pairs of opposing probes extended by wire booms with a separation distance of 6.7m. The probes have titanium nitride (TiN) surfaces, which has proved to be a material with excellent properties for providing good electrical contact between probe and plasma. The wire booms are of a new design in which the booms in the stowed position are wound around the exterior of the spacecraft body. The boom system was flown for the first time on this mission and worked flawlessly. The magnetic field is measured by a tri-axial fluxgate sensor located at the tip of a rigid, hinged boom extended along the spacecraft spin axis and facing away from the Sun. The new advanced-design fluxgate magnetometer uses digital signal processors for detection and feedback, thereby reducing the analogue circuitry to a minimum. The instrument characteristics as well as a brief review of the science accomplished and planned are presented. Key words. Ionosphere (auroral ionosphere). Magnetospheric physics (magnetosphere-ionosphere interactions). Space plasma physics (instruments and techniques)

scholarly journals First results of electric field and density observations by Cluster EFW based on initial months of operation

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1219-1240 ◽  
Author(s):  
G. Gustafsson ◽  
M. André ◽  
T. Carozzi ◽  
A. I. Eriksson ◽  
C.-G. Fälthammar ◽  
...  
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Electric Fields ◽  
Field Data ◽  
Space Plasma ◽  
Space Plasma Physics ◽  
First Results ◽  
High Coherence ◽  
Very High

Abstract. Highlights are presented from studies of the electric field data from various regions along the Cluster orbit. They all point towards a very high coherence for phenomena recorded on four spacecraft that are separated by a few hundred kilometers for structures over the whole range of apparent frequencies from 1 mHz to 9 kHz. This presents completely new opportunities to study spatial-temporal plasma phenomena from the magnetosphere out to the solar wind. A new probe environment was constructed for the CLUSTER electric field experiment that now produces data of unprecedented quality. Determination of plasma flow in the solar wind is an example of the capability of the instrument.Key words. Magnetospheric physics (electric fields) – Space plasma physics (electrostatic structures; turbulence)

SP4GATEWAY: a Space Plasma Physics Payload Package conceptual design for the Deep Space Gateway Lunar Orbital Platform

2020 ◽  
Author(s):  
Iannis Dandouras ◽  
Pierre Devoto ◽  
Johan De Keyser ◽  
Yoshifumi Futaana ◽  
Ruth Bamford ◽  
...  
Keyword(s):  
Solar Wind ◽  
Plasma Physics ◽  
Conceptual Design ◽  
Lunar Surface ◽  
Space Plasma ◽  
The Moon ◽  
Deep Space ◽  
Space Plasma Physics ◽  
Plasma Environment ◽  
Technical Requirements

<p>The Deep Space Gateway is a crewed platform that will be assembled and operated in the vicinity of the Moon by ESA and its international partners in the early 2020s and will offer new opportunities for fundamental and applied scientific research. The Moon is a unique location to study the deep space plasma environment, due to the absence of a substantial intrinsic magnetic field and the direct exposure to the solar wind, galactic cosmic rays (GCRs) and solar energetic particles (SEPs). However, 5-6 days each orbit, the Moon crosses the tail of the terrestrial magnetosphere facilitating the in-situ study of the terrestrial magnetotail plasma environment as well as atmospheric escape from the ionosphere. When back outside of the magnetosphere, a variety of these and other phenomena, e.g. those driving solar-terrestrial relationships, can be investigated through remote sensing using a variety of imaging techniques. Most importantly, the lunar environment offers a unique opportunity to study the interaction of the solar wind and the magnetosphere with the lunar surface and the lunar surface-bounded exosphere. In preparation of the scientific payload of the Deep Space Gateway, we have undertaken a conceptual design study for a Space Plasma Physics Payload Package onboard the Gateway (SP4GATEWAY). The main goal is first to provide a science rationale for hosting space plasma physics instrumentation on the Gateway and to translate that into a set of technical requirements. A conceptual payload design, that identifies a strawman payload and is compatible with the technical requirements, is then put forward. The final outcome of this project, which is undertaken following an ESA AO, is an implementation plan for this space plasma physics payload package.</p>

A Case for Magneto Hydro Dynamics (MHD)

2001 ◽  
Author(s):  
Haim H. Bau
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Lorentz Force ◽  
Electric Fields ◽  
Biological Fluids ◽  
Fluid Volume ◽  
Chaotic Advection ◽  
Complex Flows ◽  
Electric Currents

Abstract In this paper, I review some of our work on the use of magneto hydrodynamics (MHD) for pumping, controlling, and stirring fluids in microdevices. In many applications, one operates with liquids that are at least slightly conductive such as biological fluids. By patterning electrodes inside flow conduits and subjecting these electrodes to potential differences, one can induce electric currents in the liquid. In the presence of a magnetic field, a Lorentz force is generated in a direction that is perpendicular to both the magnetic and electric fields. Since one has a great amount of freedom in patterning the electrodes, one can induce forces in various directions so as to generate complex flows including “guided” flows in virtual, wall-less channels. The magnetic flux generators can be either embedded in the device or be external. Despite their unfavorable scaling (the magnitude of the forces is proportional to the fluid volume), MHD offers many advantages such as the flexibility of applying forces in any desired direction and the ability to adjust the magnitude of the forces by adjusting either the electric and/or magnetic fields. We provide examples of (i) MHD pumps; (ii) controlled networks of conduits in which each conduit is equipped with a MHD actuator and by controlling the voltage applied to each actuator, one can direct the liquid to flow in any desired way without a need for valves; and (iii) MHD stirrers including stirrers that exhibit chaotic advection.

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