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Two fluid continuum theory of incoherent scattering extended to include unequal electron and ion temperatures, considering backscatter power dependency on collision frequencies
A thorough discussion of submillimeter laser Thomson scattering for the measurement of ion temperature in plasmas is presented. This technique is very promising and work is being actively pursued on the high power lasers and receivers necessary for its implementation. In this report we perform an overall system analysis of the Thomson scattering technique aimed to: (1) identify problem areas; (2) establish specifications for the main components of the apparatus; (3) study signal processing alternatives and identify the optimum signal handling procedure. Because of its importance for the successful implementation of this technique, we also review the work presently being carried out on the optically pumped submillimeter CH3F and D2O lasers.
Geomagnetic equatorial ionospheric ion temperature, comparing incoherent scatter radar and OGO-D retarding potential analyzer values
The Schunk and Sojka (1981a, b) high latitude ionospheric model is improved through the inclusion of thermal conduction and diffusion terms in the ion energy equation, permitting the study of daytime, high latitude F layer temperature variations in a region poleward of the auroral oval. It is found that ion temperature variation with solar cycle, season and geomagnetic activity closely follows the neutral atomic oxygen variation, and that meridional electric fields of more than 40 mV/m can cause larger ion temperature changes than those due to solar cycle, seasonal or geomagnetic activity variations. In the presence of meridional electric fields, there is an upward flow of heat from the lower ionosphere that also acts to raise ion temperatures at high altitudes. Zonal electric fields affect ion temperature indirectly, through electron density changes.
A procedure for analyzing low-energy (less than approximately 100 eV) ion data from the plasma composition experiment on ISEE 1 is set forth. The method is based on a derived analytic expression for particle flux to a limited aperture retarding potential analyzer (RPA) in the thin sheath approximation, which makes allowance for some effects of a charged spacecraft on plasma particle trajectories. Calculations using simulated data are employed in testing the efficacy and accuracy of the technique. On the basis of an analysis of these calculation results and the mathematical model, the method is seen as being able to provide accurate ion temperatures from all good plasmaspheric RPA data. It is noted that corresponding densities and spacecraft potentials should be accurate when spacecraft potentials are negative but that they are subject to error for positive spacecraft potentials, particularly when ion Mach numbers are much less than 1. An analysis of data from a representative ISEE 1 pass produces a plasmasphere temperature profile that is consistent in overall structure with previous observations.
Modified Nielsen-type ion source produces temperatures up to 1500 degrees C and permits obtaining a plasma from low vapor-pressure materials. Design minimizes thermal stresses. Dual-filament discharge chamber achieves the high temperature and provides independent control of the heating and electron emission functions.
The present invention includes an apparatus, system and method for stochastic sensing of an analyte to a protein pore. The protein pore may be an engineer protein pore, such as an ion channel at temperatures above 55.degree. C. and even as high as near 100.degree. C. The analyte may be any reactive analyte, including chemical weapons, environmental toxins and pharmaceuticals. The analyte covalently bonds to the sensor element to produce a detectable electrical current signal. Possible signals include change in electrical current. Detection of the signal allows identification of the analyte and determination of its concentration in a sample solution. Multiple analytes present in the same solution may also be detected.
Elektron-2 measurements of upper limits of ion temperatures between 7000 and 30,000 km
Study of deviations from thermal equilibrium among the ions in the ionosphere by considering that the 'light' ions H(+) and He(+) may be at a different temperature from the 'heavy' ion O(+). In particular, the case in which thermal protons are observed to be flowing relative to the assumed static ambient oxygen ions is considered. The proton flow is assumed to be along the direction of the magnetic field. Of the cases tested, it is found that the measured proton temperature is from one to ten times the measured oxygen ion temperature. Such temperature enhancements may be expected both because of the energy transfer associated with the ion flow and as a consequence of the preferential energy coupling from the light-ion distribution in the exosphere.
The most important investigations leading to the International Reference Ionosphere 1990 (IRI-90) are overviewed, and the latest version of the model is described. The shortcomings and limitations of the IRI-90 are pointed out, together with the ways of overcoming them. The list of studies that the IRI group has yet to carry out includes the investigations of magnetic storm effects as the highest priority. This paper discusses determinations of and the available data on the electron density, plasma temperatures, ion composition, and ion drift in the ionosphere, together with future improvements needed on these parameters.
The effects of the grid transparency and finite collector size on the values of thermal ion density and temperature determined by the standard RPA (retarding potential analyzer) analysis method are investigated. The current-voltage curves calculated for varying RPA parameters and a given ion mass, temperature, and density are analyzed by the standard RPA method. It is found that only small errors in temperature and density are introduced for an RPA with typical dimensions, and that even when the density error is substantial for nontypical dimensions, the temperature error remains minimum.
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The analysis of ion data from retarding potential analyzers (RPA's) is generally done under the planar approximation, which assumes that the grid transparency is constant with angle of incidence and that all ions reaching the plane of the collectors are collected. These approximations are not valid for situations in which the ion thermal velocity is comparable to the vehicle velocity, causing ions to enter the RPA with high average transverse velocity. To investigate these effects, the current-voltage curves for H+ at 4000 K were calculated, taking into account the finite collector size and the variation of grid transparency with angle. These curves are then analyzed under the planar approximation. The results show that only small errors in temperature and density are introduced for an RPA with typical dimensions; and that even when the density error is substantial for non-typical dimensions, the temperature error remains minimal.
Average proton parameters in the magnetosheath downstream from the quasi-perpendicular shock (the quasi-perpendicular magnetosheath) for high solar wind dynamic pressure conditions are observed to vary continuously from high-beta, low-temperature anisotropy to low-beta, high-temperature anisotropy. Observations and theory have shown that this inverse correlation is a direct consequence of pitch angle scattering by electromagnetic ion cyclotron (EMIC) waves, which regulate the anisotropy, restoring the plasma toward marginal stability. ALthough the previously documented spectral characteristics of EMIC waves are not evident downstream of the quasi-parallel bow shock, the inverse anisotropy-beta relation found in the quasi-perpendicular magnetosheath also holds in the quasi-parallel magnetosheath. This indicates that the EMIC instability regulates the ion anisotropy regardless of the shock geometry.
The high correlation of Pc 1 events with magnetospheric compressions is known. A mechanism is proposed which leads to the generation of Pc 1 waves. The interaction of a dynamic pressure pulse with the earth's bow shock leads to the formation of a weak fast-mode shock propagating into the magnetoshealth. The shock wave can pass right through a tangential discontinuity (magnetopause) and into the magnetosphere, without disturbing either of the structures. In a quasiperpendicular geometry, the shock wave exhibits anisotropic heating. This anisotropy drives unstable ion-cyclotron waves which can contribute to the generation of the Pc 1 waves which are detected. The viability of the mechanism is demonstrated with simulations. This mechanism could explain the peak in the occurrence of observed Pc 1 waves in the postnoon sector where a field-aligned discontinuity in the solar wind would most often be parallel to the magnetopause surface due to the average Parker-spiral magnetic-field configuration.
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Two fluid continuum theory of Thomson scattering extended to uniform DC magnetic field and electron drift, finding backscattered power dependent on magnetism
Four electrostatic analyzers with channel electron multipliers as detectors were used to measure solar wind ionic flow. The axes of the fields of vision of two of these analyzers were directed along the axis of the automatic interplanetary station, oriented towards the Sun, while the other two were turned in one plane at angles of +15 deg and -15 deg. The full hemisphere of the angular diagram of each analyzer was approximately 5 deg. The energetic resolution was approximately 6%, and the geometric energy was 0.002 sq cm ave. keV. Each analyzer covered an energetic range of approximately 10 in eight energetic intervals. Spectral distributions were processed in order to obtain the velocity and temperature of the protons. Tabular data show the hour interval (universal time) and the average solar wind velocity in kilometers per second.