Synopsis of Mid-latitude Radio Wave Absorption in Europe

Radio wave absorption data covering almost two years from Europe to Central Asia are presented. They are normalized by relating them to a reference absorption. Every day these normalized data are fitted to a mathematical function of geographical location in order to obtain a daily synopsis of radio wave absorption. A film of these absorption charts was made which is intended to reveal movements of absorption or absorption anomaly. In addition, radiance (temperature) data from the lower D-region are also plotted onto these charts

The Application of Waste Silica Cyclone Powder for the Protective Coating of Steel Billets

The role of a protective coating is to diminish the steel surface scaling during the reheating for hot rolling. The protective coating consists of several components, and the effect of the coating is based on the formation of the modification of Al2O3, amorphous SiO2 and FeO×Al2O3, which all exhibit low permeability to oxygen at temperature up to 1200 °C. The silica sand powder from the cyclone is a waste product in the separation of silica sand. Tests confirmed that waste cyclone powder could replace the silica flour as one of the ingredients in the protective coating. The results of the efficiency of the protective coating after the advanced application of waste cyclone powder on AISI 1059 and AISI 6150 steels are presented. The application of the coating decreased the oxidation and decarburisation of the steel surface during the reheating for hot rolling

The Application of Waste Silica Cyclone Powder for the Protective Coating of Steel Billets

The role of a protective coating is to diminish the steel surface scaling during the reheating for hot rolling. The protective coating consists of several components, and the effect of the coating is based on the formation of the modification of Al2O3, amorphous SiO2 and FeO×Al2O3, which all exhibit low permeability to oxygen at temperature up to 1200 °C. The silica sand powder from the cyclone is a waste product in the separation of silica sand. Tests confirmed that waste cyclone powder could replace the silica flour as one of the ingredients in the protective coating. The results of the efficiency of the protective coating after the advanced application of waste cyclone powder on AISI 1059 and AISI 6150 steels are presented. The application of the coating decreased the oxidation and decarburisation of the steel surface during the reheating for hot rolling

Bite-outs and other depletions of mesospheric electrons

The ionised mesosphere is less understood than other parts of the ionosphere because of the challenges of making appropriate measurements in this complex region. We use rocket borne in situ measurements of absolute electron density by the Faraday rotation technique and accompanying DC-probe measurements to study the effect of particles on the D-region charge balance. Several examples of electron bite-outs, their actual depth as well as simultaneous observations of positive ions are presented. For a better understanding of the various dependencies we use the ratio Β/αi (attachment rate over ion-ion recombination coefficient), derived from the electron and ion density profiles by applying a simplified ion-chemical scheme, and correlate this term with solar zenith angle and moon brightness. The probable causes are different for day and night; recent in situ measurements support existing hypotheses for daytime cases, but also reveal behaviour at night hitherto not reported in the literature. Within the large range of Β/αi values obtained from the analysis of 28 high latitude night flights one finds that the intensity of scattered sunlight after sunset, and even moonlight, apparently can photodetach electrons from meteoric smoke particles (MSP) and molecular anions. The large range of values itself can best be explained by the variability of the MSPs and by occasionally occurring atomic oxygen impacting on the negative ion chemistry in the night-time mesosphere under disturbed conditions

SEM, AES, WDS i korozijsko testiranje oksidnih i nitridnih zaštitnih slojeva oblikovanih toplinskom obradom nerđajućeg čelika

Protective oxide and/or nitride layers on AISI 321 stainless steel were prepared by thermal treatment in air and two controlled atmospheres in a laboratory simulation of an actual technological procedure. Samples’ surface was imaged by Scanning Electron Microscopy (SEM), elemental composition of the substrates was checked by Wavelength Dispersive Spectroscopy (WDS) and depth profiles of the samples were measured by Auger Electron Spectroscopy (AES). Since protective layer thicknesses were found to be of the order of hundreds of nanometers an attempt was made to obtain some fast averaged information about layers composition by Wavelength Dispersive Spectroscopy (WDS) with appropriately adjusted primary beam energy. Electrochemical corrosion testing was also performed on samples.Zaštitne oksidne i/ili nitridne slojeve na AISI 321 nerđajućem čeliku pripremljen toplinskom obradom materijala na zraku i u 2 kontrolirana tipa atmosfera kao laboratorijsku simulaciju stvarnog tehnološkog procesa. Slike površine uzoraka dobijene tehnikom SEM, sastav substrata metodom WDS a za profilnu analizu upotrijebljena je spektroskopija Augerovih elektrona (AES). Kako je ustanovljeno da su debljine formiranih zaštitnih slojeva reda veličine nekoliko stotina nanometara pokušalo se doći do ocjene o prosječnom sastavu unutar sloja upotrijebom tehnike WDS uz odgovarajuće odabranu energiju primarnog elektronskog snopa. Na uzorcima je provjereno i korozijsko testiranje

South‐North Hemispheric Asymmetry of the FAE Distribution Around the Cusp Region: Cluster Observation

Cluster data from late July to early October were used to study the distribution of field‐aligned electron (FAE) events around the two cusps. An FAE event was defined as electron parallel flux >3 × 108 (cm2 s)−1. The total number of FAE events around the two cusps was basically identical, but downward FAE events prevailed in the south and upward FAE events in the north. In the southern cusp, the peak of the FAE events distribution versus altitude was about 1.3 RE higher and the peak of the FAE events distribution versus invariant latitude (ILAT) was about 4° ILAT lower. Only the downward FAEs around the southern cusp had a second ILAT peak, which was located about 11° higher than the main peak. The normalized number of FAEs showed nearly the same features as the unnormalized number of the FAEs events. These results indicated a north‐south asymmetry of the FAE distribution around the two cusps. Some causes for the asymmetry are discussed, the main ones being the asymmetry of the magnetospheric configuration resulting from geomagnetic dipolar tilt and solar wind flows, the interplanetary magnetic field asymmetry related to the magnetosphere, and the difference of ionospheric conductivity in the two hemispheres. Various solar wind‐magnetosphere interaction processes, such as quasi‐viscous interaction and reconnection, are responsible for the asymmetry, too. The second distribution peak (at higher ILAT) of the downward FAE events around the southern cusp corresponded to high solar wind speed and may be associated with the northward interplanetary magnetic field Bz field‐aligned current at low altitude. This requires further studies, however

Impact of the solar wind dynamic pressure on the field‐aligned currents in the magnetotail: Cluster observation

We statistically investigate the influence of the solar wind dynamic pressure (SW Pdyn) on the field-aligned currents (FACs) in the magnetotail with 1492 FAC cases from July to October in 2001 and 2004, which covers 74 Cluster crossings of the plasma sheet boundary layer (PSBL) in both storm time and non-storm time. The FAC density in the magnetotail is derived from the magnetic field data with the four-point measurement of Cluster, and the SW Pdyn is taken from ACE data. The results indicate the FAC density becomes stronger with increasing SW Pdyn. The statistics show that the FAC occurrence increased monotonically with SW Pdyn in the three levels (Weak: SW Pdyn5 nPa). The FAC density increased with increasing SW Pdyn, while its footprint (invariant latitude, ILAT) in the polar region decreased with increasing SW Pdyn. The response of the FAC to SW Pdyn in the magnetotail had a north-south hemispheric asymmetry. The FAC density had a better correlation with SW Pdyn in the Northern hemisphere, while the footprint had a better correlation with SW Pdyn in the Southern hemisphere. Possible underlying mechanisms for our results are analyzed and discussed. However, it requires more observations and simulation studies to find out the mechanism of north-south asymmetry

The ECOMA 2007 campaign: Rocket observations and numerical modelling of aerosol particle charging and plasma depletion in a PMSE/NLC layer

The ECOMA series of rocket payloads use a set of aerosol particle, plasma, and optical instruments to study the properties of aerosol particles and their interaction with the ambient plasma environment in the polar mesopause region. In August 2007 the ECOMA-3 payload was launched into a region with Polar Mesosphere Summer Echoes (PMSE) and noctilucent clouds (NLC). An electron depletion was detected in a broad region between 83 and 88 km, coincident with enhanced density of negatively charged aerosol particles. We also find evidence for positive ion depletion in the same region. Charge neutrality requires that a population of positively charged particles smaller than 2 nm and with a density of at least 2×108 m−3 must also have been present in the layer, undetected by the instruments. A numerical model for the charging of aerosol particles and their interaction with the ambient plasma is used to analyse the results, showing that high aerosol particle densities are required in order to explain the observed ion density depletion. The model also shows that a very high photoionisation rate is required for the particles smaller than 2 nm to become positively charged, indicating that these may have a lower work function than pure water ice