The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN Spacecraft

We analyzed 44 passes of the MAVEN spacecraft through the magnetosphere, arranged by the angle between electric field vector and the projection of spacecraft position radius vector in the YZ plane in MSE coordinate system (${\theta}$ E ). All passes were divided into 3 angular sectors near 0{\deg}, 90{\deg} and 180{\deg} ${\theta}$ E angles in order to estimate the role of IMF direction in plasma and magnetic properties of dayside Martian magnetosphere. The time interval chosen was from January 17 through February 4, 2016 when MAVEN was crossing the dayside magnetosphere at SZA ~ 70{\deg}. Magnetosphere as the region with prevailing energetic planetary ions is always found between the magnetosheath and the ionosphere. 3 angular sectors of dayside interaction region in MSE coordinate system with different orientation of the solar wind electric field vector E = -1/c V x B showed that for each sector one can find specific profiles of the magnetosheath, the magnetic barrier and the magnetosphere. Plume ions originate in the northern MSE sector where motion electric field is directed from the planet. This electric field ejects magnetospheric ions leading to dilution of magnetospheric heavy ions population, and this effect is seen in some magnetospheric profiles. Magnetic barrier forms in front of the magnetosphere, and relative magnetic field magnitudes in these two domains vary. The average height of the boundary with ionosphere is ~530 km and the average height of the magnetopause is ~730 km. We discuss the implications of the observed magnetosphere structure to the planetary ions loss mechanism.Comment: 24 pages, 13 figure

Accelerated Electrons in Cassiopeia A: An Explanation for the Hard X-ray Tail

We propose a model for the hard X-ray (> 10 keV) emission observed from the supernova remnant Cas A. Lower hybrid waves are generated in strong (mG) magnetic fields, generally believed to reside in this remnant, by shocks reflected from density inhomogeneities. These then accelerate electrons to energies of several tens of keV. Around 4% of the x-ray emitting plasma electrons need to be in this accelerated distribution, which extends up to electron velocities of order the electron Alfven speed, and is directled along magnetic field lines. Bremsstrahlung from these electrons produces the observed hard x-ray emission. Such waves and accelerated electrons have been observed in situ at Comet Halley, and we discuss the viability of the extrapolation from this case to the parameters relevant to Cas A.Comment: 20 pages, 3 figures, aasTeX502, accepted in Ap

On Collisionless Electron-Ion Temperature Equilibration in the Fast Solar Wind

We explore a mechanism, entirely new to the fast solar wind, of electron heating by lower hybrid waves to explain the shift to higher charge states observed in various elements in the fast wind at 1 A.U. relative to the original coronal hole plasma. This process is a variation on that previously discussed for two temperature accretion flows by Begelman & Chiueh. Lower hybrid waves are generated by gyrating minor ions (mainly alpha-particles) and become significant once strong ion cyclotron heating sets in beyond 1.5 R_sun. In this way the model avoids conflict with SUMER electron temperature diagnostic measurements between 1 and 1.5 R_sun. The principal requirement for such a process to work is the existence of density gradients in the fast solar wind, with scale length of similar order to the proton inertial length. Similar size structures have previously been inferred by other authors from radio scintillation observations and considerations of ion cyclotron wave generation by global resonant MHD waves.Comment: 32 pages including 11 figures, 4 tables, accepted by Ap

Initial observations of fine plasma structures at the flank magnetopause with the complex plasma analyzer SCA-1 onboard the Interball Tail Probe

International audienceThe fast plasma analyzer EU-1 of the SCA-1 complex plasma spectrometer is installed onboard the Interball Tail Probe (Interball-1). It provides fast three-dimensional measurements of the ion distribution function on the low-spin-rate Prognoz satellite (about 2min). The EU-1 ion spectrometer with virtual aperture consists of two detectors with 16 E/Q narrow-angle analyzers and electrostatic scanners. This configuration allows one to measure the ion distribution function in three dimensions (over 15 energy steps in 50 eV/Q?5.0 keV/Q energy range in 64 directions) in 7.5 s, which makes it independent of the slow rotation speed of the satellite. A description of the instrument and its capabilities is given. We present here the preliminary results of measurements of ions for two cases of the dawn low- and mid-latitude magnetopause crossings. The properties of observed ion structures and their tentative explanation are presented. The 12 September 1995 pass at low latitude at about 90° solar-zenith angle on the dawn side of the magnetosphere is considered in more detail. Dispersive ions are seen at the edge of the magnetopause and at the edges of subsequently observed plasma structures. Changes in ion velocity distribution in plasma structures observed after the first magnetopause crossing suggest that what resembles multiple magnetopause crossings may be plasma blobs penetrating the magnetosphere. Observed variations of plasma parameters near magnetopause structures suggest nonstationary reconnection as the most probable mechanism for observed structures

Theory of differential inclusions and its application in mechanics

The following chapter deals with systems of differential equations with discontinuous right-hand sides. The key question is how to define the solutions of such systems. The most adequate approach is to treat discontinuous systems as systems with multivalued right-hand sides (differential inclusions). In this work three well-known definitions of solution of discontinuous system are considered. We will demonstrate the difference between these definitions and their application to different mechanical problems. Mathematical models of drilling systems with discontinuous friction torque characteristics are considered. Here, opposite to classical Coulomb symmetric friction law, the friction torque characteristic is asymmetrical. Problem of sudden load change is studied. Analytical methods of investigation of systems with such asymmetrical friction based on the use of Lyapunov functions are demonstrated. The Watt governor and Chua system are considered to show different aspects of computer modeling of discontinuous systems

Hot flow anomalies at Venus

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95474/1/jgra21752.pd