He++ behavior on the an interplanetary shock wave

<p>In our study we analyzing the fine structure of interplanetary shock wave fronts recorded by the BMSW experiment, installed onboard the SPEKTR-R satellite. The high time resolution of the spectrometer (0.031 s for the plasma flux magnitude and direction and 1.5 s for velocity, temperature, and density) makes it possible to study the internal structure of the IPs front.</p><p>BMSW experiment registered 55 IPs waves from 2011 to 2019. For 21 events (where the temperature was not very high), the parameters of twice-ionized helium (He++ or α-particles) - density (absolute value and relative to protons content in the solar wind plasma), velocity, temperature. It is shown that the speed of He++ is slightly less (for about 5%) than the speed of protons, the relative density of He++ rarely exceeds 10%, and the temperature of He++ is about 2 times higher than the temperature of protons.</p><p>On the IPs front, short-term and significant (up to 20%) jumps in the relative density of He++ were detected in several events. No dependence was found between Mms/proton beta and He++ density changing after IPs front. However, we detected that the lower Qbn parameter is, the more the relative density of He++ falls behind the IPs front.</p>

Fluid model of the plasma flow in the magnetic tail of a planet

<p>All planets of the solar system with an active internal dynamo have a their magnetic dipole oriented perpendicularly or nearly perpendicularly to the solar wind during all or part of their orbit  around the Sun. If, in addition, the planetary rotation is slow, or if the angle between dipole and rotation axis is large, planetary field lines crossing the antisolar axis can become stretched to large distances downstream of the planet. Examples where this may occur are Mercury and Uranus at solstice time, respectively. </p><p>Inspired by these examples, we present a tentative one-dimensional magnetohydrodynamic model of the plasma flowing along the antisolar direction. </p><p>Assuming that the radius of curvature R(z) of the planetary field lines is defined locally as R=D/D', where D(z) is a characteristic  transverse scale of the magnetosphere at a distance z downstream of the planet,  we obtain that the plasma velocity u(z) obeys to a Hugoniot type equation  (M<sup>2</sup>-1) u'/u =  D'/D,  where M=u/v<sub>A</sub> is the Alfvén Mach number. </p><p>The solution for a typical profile D(z) will be discussed. </p>

The electrodynamic influence of thermospheric winds in the daytime ionosphere.

<p>The electrodynamic influence of thermospheric winds is an effect thought to dominate the development of<span> </span>the daytime low-latitude ionosphere, through the generation of dynamo currents and associated vertical plasma drifts. Until recently, observations of the thermospheric and ionopsheric state variables have mainly been defined and compared on climatological time scales, due to their collection from separate observatories with disparate measurement capabilities.<span>  </span>These datasets are inadequate for investigation of the actual action of thermospheric drivers as they modify the ionospheric state, as the response clearly changes on 24-hour timescales, and shorter when viewed in the a constant-local-time frame<span> </span>of reference. New observatiions of thermospheric winds, uninterrupted over the 90-300 km altitude range, are now provided by the Ionospheric Connection Explorer along with simultaneous plasma velocity and density measurments. These observations are directly comparable to the wind measurements in crossings of the magnetic equator, where the winds are magnetically conjugate to the drift measurements. Investigation of the noon-sector drifts vs wind drivers is presented. We find that the local driver is clearly evident in the noon-time vertical plasma drifts under all conditions.</p><p> </p>

Control of ionospheric plasma velocities by thermospheric winds

Earth’s equatorial ionosphere exhibits significant and unpredictable day-to-day variations in density and morphology . This presents difficulties in preparing for adverse impacts on technological systems even 24 hours in advance . This behavior is now theoretically understood as a manifestation of thermospheric weather, where conditions in the upper atmosphere respond strongly to changes in the spectrum of atmospheric waves that propagate into space from the lower and middle atmosphere, modifying the electrodynamic environment that exerts control over the creation of plasma . The NASA Ionospheric Connection Explorer (ICON) makes the first coordinated space-based observations of the wind-driven dynamo and the plasma state to understand the relation of the plasma environment to the thermospheric weather below. Here we show the first direct measurements of the effects of a wind-driven dynamo in space, where a clear relationship is found between the vertical plasma velocities measured at the magnetic equator near 600 km and the thermospheric winds much farther below, with substantial correlations found between the plasma velocity and thermospheric winds during each of several successive precession cycles of the observatory’s orbit. Prediction of thermospheric winds in the 100 – 150 km range emerges as a key to improved prediction of the Earth’s plasma environment.

Quasi-6-day wave effects in ionospheric E and F region during the recent solar maximum 2014–2015

We show the statistical characteristics of quasi-6-day wave (Q6DW) absolute amplitude in foE and foF2 during 2014–2015 by using six ionosondes at different latitudes. The results show that foE perturbations maximized at mid-latitudes during equinoxes, and the maximum amplitude of Q6DW in foF2 occurred near the northern crest of equatorial ionospheric anomaly (EIA). In addition, the absolute amplitude of Q6DW in foF2 increased with increasing solar activity. Our observations suggest that the dissipative Q6DW-like oscillations in the lower thermosphere may cause variations in the thermospheric neutral density via mixing effect and further result in foE disturbances in Q6DW events. Furthermore, the E region wind dynamo could also be modulated by the 6-day wave, thus leading to the disturbances in vertical plasma velocity via E × B drifts and F region electron density. Our observational investigation provides evidence of thermosphere–ionosphere coupling in the mid- and low-latitude region.

The Role of Field-Aligned Current Closure on the E and F-Region Coupled Thermosphere-Ionosphere

<p>In this study, the behaviour of both E and F-region neutral winds are examined in the vicinity of intense R1 and R2 field-aligned currents (FACs), measured by AMPERE. This is achieved through the dual sampling of both the green (557.5nm) and red (630nm) auroral emissions, sequentially, from a ground based Scanning Doppler Imager (SDI) located in Alaska.</p><p>With the addition of plasma velocity data from the Super Dual Auroral Radar Network (SuperDARN) and ionospheric parameters from the Poker Flat Incoheerent Scatter Radar (PFISR), we assess how the large closure of Pedersen currents (implied by the strong FACs) modifies the spatial and temporal structure of the neutral wind at different altitudes. We find that the thermosphere becomes significantly height dependent, which could indicate a broader altitude range where the Pedersen conductivity is more important during intense FAC closure.</p>

Локальные измерения флуктуаций радиальной скорости плазмы в токамаке ФТ-2 с помощью экваториального усиленного рассеяния

The possibility of local measurements of the level of the radial plasma velocity fluctuations by the equatorial enhanced scattering of a narrow microwave beam in the upper hybrid resonance in the core plasma of a tokamak is demonstrated. The limitations of the proposed method are clarified at the periphery of the plasma, where the amplitude of density fluctuations grows and small-angle scattering of microwaves on them along the path to the upper hybrid resonance and back becomes significant.

Investigations of Atmospheric Waves in the Earth Lower Ionosphere by Means of the Method of the Creation of the Artificial Periodic Irregularities of the Ionospheric Plasma

We present results of the studies of internal gravity waves based on altitude-time dependences of the temperature and the density of the neutral component and the velocity of the vertical plasma motion at altitudes of the lower ionosphere (60–130 km). The vertical plasma velocity, which in the specified altitude range is equal to the velocity of the neutral component, the temperature, and the density of the neutral atmosphere are determined by the method of the resonant scattering of radio waves by artificial periodic irregularities (APIs) of the ionosphere plasma. We have developed an API technique and now we are evolving it for studying the ionosphere and the neutral atmosphere using the Sura heating facility (56.1 N; 46.1 E), Nizhny Novgorod, Russia. An advantage of the API technique is the opportunity to determine the parameters of the undisturbed natural environment under a disturbance of the ionosphere by a field of powerful high frequency radio waves. Analysis of altitude-time variations of the neutral temperature, the density, and the vertical plasma velocity allows one to estimate periods of atmospheric waves propagation. Wavelike variations with a period from 5 min to 3 h and more are clearly determined.