Coronal fast wave trains of the decimetric type IV radio event observed during the decay phase of the June 6, 2000 flare

The 22 min long decimetric type IV radio event observed during the decay phase of the June 6, 2000 flare simultaneously by the Brazilian Solar Spectroscope (BSS) and the Ond?ejov radiospectrograph in frequency range 1200–4500 MHz has been analyzed. We have found that the characteristic periods of about 60 s belong to the long-period spectral component of the fast wave trains with a tadpole pattern in their wavelet power spectra. We have detected these trains in the whole frequency range 1200–4500 MHz. The behavior of individual wave trains at lower frequencies is different from that at higher frequencies. These individual wave trains have some common as well as different properties. In this paper, we focus on two examples of wave trains in a loop segment and the main statistical parameters in their wavelet power and global spectra are studied and discussed.     

Nonclassical Transport and Particle-Field Coupling: from Laboratory Plasmas to the Solar Wind

Understanding transport of thermal and suprathermal particles is a fundamental issue in laboratory, solar-terrestrial, and astrophysical plasmas. For laboratory fusion experiments, confinement of particles and energy is essential for sustaining the plasma long enough to reach burning conditions. For solar wind and magnetospheric plasmas, transport properties determine the spatial and temporal distribution of energetic particles, which can be harmful for spacecraft functioning, as well as the entry of solar wind plasma into the magnetosphere. For astrophysical plasmas, transport properties determine the efficiency of particle acceleration processes and affect observable radiative signatures. In all cases, transport depends on the interaction of thermal and suprathermal particles with the electric and magnetic fluctuations in the plasma. Understanding transport therefore requires us to understand these interactions, which encompass a wide range of scales, from magnetohydrodynamic to kinetic scales, with larger scale structures also having a role. The wealth of transport studies during recent decades has shown the existence of a variety of regimes that differ from the classical quasilinear regime. In this paper we give an overview of nonclassical plasma transport regimes, discussing theoretical approaches to superdiffusive and subdiffusive transport, wave–particle interactions at microscopic kinetic scales, the influence of coherent structures and of avalanching transport, and the results of numerical simulations and experimental data analyses. Applications to laboratory plasmas and space plasmas are discussed.     

Application of the graph-analytical method of tree risk assessment to study survivability of small trust liquid rocket engines

The present paper discusses a need to develop a methodology of predicting the reliability of small thrust liquid rocket engines with a flow section made of composite materials under actual operating conditions for their successful practical use in the propulsion systems.     

Potential Effects of Surface Temperature Variations and Disturbances and Thermal Convection on the Mars InSight HP<Superscript>3</Superscript> Heat-Flow Determination

The HP³ instrument on the InSight lander mission will measure subsurface temperatures and thermal conductivities from which heat flow in the upper few meters of the regolith at the landing site will be calculated. The parameter to be determined is steady-state conductive heat flow, but temperatures may have transient perturbations resulting from surface temperature changes and there could be a component of thermal convection associated with heat transport by vertical flow of atmospheric gases over the depth interval of measurement. The experiment is designed so that it should penetrate to a depth below which surface temperature perturbations are smaller than the required measurement precision by the time the measurements are made. However, if the measurements are delayed after landing, and/or the probe does not penetrate to the desired depth, corrections may be necessary for the transient perturbations. Thermal convection is calculated to be negligible, but these calculations are based on unknown physical properties of the Mars regolith. The effects of thermal convection should be apparent at shallow depths where transient thermal perturbations would be observed to deviate from conductive theory. These calculations were required during proposal review and their probability of predicting a successful measurement a prerequisite for mission approval. However, their uncertainties lies in unmeasured physical parameters of the Mars regolith.     

Space–Time Structure of Energetic Electron Precipitations according to the Data of Balloon Observations and Polar Satellite Measurements on February 1–6, 2015

Cosmic Research - The results of an analysis of the space–time characteristics and dynamics of precipitations of magnetospheric electrons with energies in the range from 0.1 to 0.7 MeV are...     

Comparison of ionospheric F2 peak parameters foF2 and hmF2 with IRI2001 at Hainan

Monthly median values of foF2, hmF2 and M(3000)F2 parameters, with quarter-hourly time interval resolution for the diurnal variation, obtained with DPS4 digisonde at Hainan (19.5°N, 109.1°E; Geomagnetic coordinates: 178.95°E, 8.1°N) are used to investigate the low-latitude ionospheric variations and comparisons with the International Reference Ionosphere (IRI) model predictions. The data used for the present study covers the period from February 2002 to April 2007, which is characterized by a wide range of solar activity, ranging from high solar activity (2002) to low solar activity (2007). The results show that (1) Generally, IRI predictions follow well the diurnal and seasonal variation patterns of the experimental values of foF2, especially in the summer of 2002. However, there are systematic deviation between experimental values and IRI predictions with either CCIR or URSI coefficients. Generally IRI model greatly underestimate the values of foF2 from about noon to sunrise of next day, especially in the afternoon, and slightly overestimate them from sunrise to about noon. It seems that there are bigger deviations between IRI Model predictions and the experimental observations for the moderate solar activity. (2) Generally the IRI-predicted hmF2 values using CCIR M(3000)F2 option shows a poor agreement with the experimental results, but there is a relatively good agreement in summer at low solar activity. The deviation between the IRI-predicted hmF2 using CCIR M(3000)F2 and observed hmF2 is bigger from noon to sunset and around sunrise especially at high solar activity. The occurrence time of hmF2 peak (about 1200 LT) of the IRI model predictions is earlier than that of observations (around 1500 LT). The agreement between the IRI hmF2 obtained with the measured M(3000)F2 and the observed hmF2 is very good except that IRI overestimates slightly hmF2 in the daytime in summer at high solar activity and underestimates it in the nighttime with lower values near sunrise at low solar activity.     

Cluster observations showing the indication of the formation of a modified-two-stream instability in the geomagnetic tail

This study presents several observations of the Cluster spacecraft on September 24, 2003 around 15:10 UT, which show necessary prerequisites and consequences for the formation of the so-called modified-two-stream instability (MTSI). Theoretical studies suggest that the plasma is MTSI unstable if (1) a relative drift of electrons and ions is present, which exceeds the Alfvèn speed, and (2) this relative drift or current is in the cross-field direction. As consequences of the formation of a MTSI one expects to observe (1) a field-aligned electron beam, (2) heating of the plasma, and (3) an enhancement in the B-wave spectrum at frequencies in the range of the lower-hybrid-frequency (LHF). In this study we use prime parameter data of the CIS and PEACE instruments onboard the Cluster spacecraft to verify the drift velocities of ions and electrons, FGM data to calculate the expected LHF and Alfvèn velocity, and the direction of the current. The B-wave spectrum is recorded by the STAFF instrument of Cluster. Finally, a field aligned beam of electrons is observed by 3D measurements of the IES instrument of the RAPID unit. Observations are verified using a theoretical model showing the build-up of a MTSI under the given circumstances.     

Are small-scale field-aligned currents and magnetosheath-like particle precipitation signatures of the same low-altitude cusp?

We examined some 75 observations from the low-altitude Earth orbiting DMSP, Ørsted and CHAMP satellites which were taken in the region of the nominal cusp. Our objective was to determine whether the actually observed cusp locations as inferred from magnetosheath-like particle precipitation (“particle cusp”) and intense small-scale magnetic field variations (“current cusp”), respectively, were identical and were consistent with the statistically expected latitude of the cusp derived from a huge number of charged particle spectrograms (“statistical cusp”).