Measurements Of Electron Concentration Research Articles

Double Probe Measurements of Electron Temperatures in a Shock Tube

The measurement of electron temperatures and concentration in shock- generated plasmas by Langmuir probes generally is not reproducible. A double probe is designed with a hairpin geometry for easier cleaning by means of an electric current passed through the probe between shocks. Measurements are very reproducible for this probe, and some measurements are compared with expected values.

Analysis of results of simultaneous measurements of electron concentration in the ionosphere by ionosphere stations and rockets

Calculated height-frequency curves are compared with actual characteristic curves obtained at an ionosphere station in the neighborhood of the rocket's firing point. It is shown that the calculated curves are close to the actual curves and, in particular, have the same height breaks. The closeness of the height-frequency curves obtained from rocket measurements of the electron concentration distribution to height-frequency curves obtained by ionospheric sounding from the earth confirms the reliability of the rocket measurements and the correctness of the conclusions that the region of the ionosphere at altitudes of 100-300 kin is a medium with a steady rise in the electron concentration and does not break down into separate layers. (C.E.S.)

Measurements of electron concentration in the ionosphere up to altitudes of 420–470 km, carried out during the international geophysical year by means of radio-wave transmissions from the geophysical rockets of the academy of sciences U.S.S.R.

Problems relating to methods for measuring radio-wave dispersion and the Faraday effect, as employed in the determination of the electron concentration, are examined. Results of measurements carried out during the launching of 3 geophysical rockets to 450 to 470 km altitude, in l958, are presented. Measurements were performed at different times of the day and year, over the same geographicaI point, and by the same method. The n/sub e/ distribution with altitude was determined for the outer ionosphere. (L.N.N.)

Measurements of electron concentration in the ionosphere up to altitudes of 420–470 km, carried out during the International Geophysical Year by means of radio-wave transmissions from the geophysical rockets of the Academy of Sciences U.S.S.R.: K. I. Gringauz and V. A. Rudakov (pp. 48–62)

LISA Pathfinder is an ESA mission due to be launched in the next two years. The gravity gradiometer onboard has the sensitivity required to test predictions by gravitational theories proposed as alternatives to Dark Matter such as TeVeS. Within the Solar System measurable effects are predicted only in the vicinity of gravitational saddle points (SP). For this reason it has been proposed to fly LPF by the Earth–Sun SP, at some 259,000 km from Earth. This could be done in an extension to the nominal mission which uses a Lissajous orbit about the Earth–Sun L1 point. The responsibility for LPF mission design lies with ESA/ESOC, who have designed the transfer trajectories, orbits about L1, and station keeping strategies. This article describes an analysis performed by Astrium to support a suggestion for a possible mission extension to a saddle point crossing. With only very limited fuel availability, reaching the saddle point is a significant challenge. In this article, we present recent advances in the work on trajectory design. It is demonstrated that reaching the SP is feasible once the LPF mission is completed. Furthermore, in a significant enhancement, it is demonstrated that trajectories including more than one SP flyby are possible, thus improving the science return for this proposed mission extension.

Suggested origin of the anomalous line-reversal temperatures in the reaction zone of hydrocarbon flames

Measurements of electron concentrations by the method of cyclotron resonance, and of non-thermal iron line intensities in emission, as a function of composition and dilution in the reaction zone of low-pressure acetylene-oxygen-argon mixtures, reveal a marked similarity in behaviour of these two quantities. On this and other circumstantial evidence, the possible causes of the anomalous line reversals can be narrowed down to two, neither of which can, however, be considered objection-free until further experimental evidence reveals in even more detail the nature of certain of the reaction steps proposed. One of these schemes involves postulating the bimolecular production of an excited species Y∗ by the mechanism also responsible for electron production. Species Y∗ must be sufficiently energetic, and be present in sufficient quantity, to produce excited metal atom M∗ by energy transfer with M. The other—a more specific scheme—involves reaction between M+ and e− to produce M∗ the emitted radiation being discrete. Although there is experimental evidence for all the important steps involved in this second scheme, this scheme, too, can fail if the cross sections for capture of e− by M+ prove to be too small. Schemes so far postulated involving termolecular reactions are eliminated as not satisfying the experimental observations presented.

Rocket measurements of electron concentration in the ionosphere, using an ultra-shortwave dispersion interferometer: K. I. Gringauz: (pp. 62–66)

Rocket measurements of electron concentration in the ionosphere, using an ultra-shortwave dispersion interferometer: K. I. Gringauz: (pp. 62–66)

New Experimental Results for Plasma Electron Oscillations†

ABSTRACT This paper contains an account of some experimental investigations of plasma electron oscillations in low-pressure mercury vapour discharges with plane oxide coated cathodes. The appearances of some of the discharges are described. The primary electrons were deviated laterally in or near the meniscus-shaped region of ionized gas brighter than the surrounding plasma, which appeared a few millimetres from the cathode. Variation of anode-cathode separation was found to have a marked effect on both the appearance of the deflected beams and the meniscus, and on the high-frequency oscillatory properties of the discharges. Measurements of plasma electron concentration and temperature were made simultaneously with measurements of oscillation intensity and frequency. A strong tendency was found for the oscillations to grow in amplitude when the beam of primary electrons moved down a concentration gradient and to die out when the beam moved up a gradient. The frequency of the oscillation was found to agree...