T. D. Carozzi

Observations of auroral broadband emissions by CLUSTER

We present the results of a study based on several events of broadband ULF/ELF emissions observed in the auroral region by the CLUSTER multi-spacecraft at distances around 4-5 R E . These emissions, observed below the ion plasma frequency, are similar to the broadband emissions observed at lower altitudes (800-4000 km) by rockets (e.g. AMICIST) and satellites (e.g. FREJA and FAST). As successive passages of the four CLUSTER satellites through nearly the same regions show, the intensity of the emissions depend on the thermal properties of the plasma and gradients thereof. The total Poynting flux is downward and is comparable to energy fluxes observed at lower altitudes. We believe the broadband emissions are the result of dispersed Alfven waves (DAW), which propagates down the magnetic field lines, and emits higher frequency ion plasma wave modes.

Temporal evolution of HF-excited plasma waves, measured at different pump frequencies by stimulated electromagnetic emission (SEE)

Experimental results concerning the growth and decay times of different spectral components of stimulated electromagnetic emission (SEE) are presented. A new method of measurement, employing a spec ...

Full polarimetry measurements of stimulated electromagnetic emissions: First results

A theory and technique for the measurement of the full state of polarization (SOP) for wideband electromagnetic HF emissions from the ionosphere are introduced. The technique was employed in a recent experiment at the Sura ionospheric HF pumping facility near Nizhniy Novgorod, Russia, to measure the full SOP of stimulated electromagnetic emissions (SEE) in their steady state. Measurements were made for O-mode polarized pump waves at two different frequencies: one below and one slightly above the fourth electron gyroharmonic frequency. The wideband spectral parameters measured in this experiment include the horizontal intensity, the degree of horizontal circular polarization, the degree of horizontal polarization and the tilt angle of the horizontal polarization ellipse. Evaluation of the data collected demonstrates that the technique can be used for HF polarimetry and that, in particular, such measurements provide useful new diagnostics for SEE. Among the most important results regarding the polarimetry of SEE were low degrees of circular polarization in the frequency range between the peak of the broad upshifted maximum and the pump; some SEE features had degree of circularity and tilt angle values that were consistent with slightly oblique waves indicative of a distributed SEE source region; and the pump was found to have changed from an initial left-handed polarized state to a right-handed polarized state during steady state.

Experimental studies of wave-particle interactions in space using particle correlators: Results and future developments

The technique of particle correlation measures directly electron modulations that result from naturally occurring and actively stimulated wave-particle interactions in space plasmas. In the past this technique has been used for studies of beam-plasma interactions, caused by both natural auroral electron beams via sounding rockets and by artificially generated electron beams on Space Shuttle missions (STS-46, STS-75). It has also been applied to studies of how electrons become energised by waves injected from in-situ transmitters (e.g OEDIPUS-C sounding rocket). All four ESA Cluster-II spacecraft launched in 2000 to study the outer magnetosphere, cusp, and bow shock were implemented with electron correlators. Here the prevalent weaker wave-particle interactions have been more difficult to extract, however, the application of new statistical algorithms has permitted these correlators to provide a novel insight into the plasma turbulence that occurs. Present work involves technical improvements to both sensor design and correlator implementation that enable many electron energy-angle combinations to be simultaneously monitored for wave-particle interactions. A broad energy-angle range spectrograph connected to a multi-channel, multi-frequency range FPGA implemented array of correlators is scheduled to fly early 2004. Neural network techniques previously flown on STS-46 and STS-75, and statistical tests developed for Cluster-II will be used on-board to select data to be transmitted.

On the similarity of information energy to dark energy

Information energy is shown here to have properties similar to those of dark energy. The energy associated with each information bit of the universe is found to be defined identically to the characteristic energy of a cosmological constant. Two independent methods are used to estimate the universe information content of 1091 bits, a value that provides an information energy total comparable to that of dark energy. Information energy is also found to have a significantly negative equation‐of‐state parameter, w < −0.4, and thus exerts a negative pressure, similar to dark energy.Information energy is shown here to have properties similar to those of dark energy. The energy associated with each information bit of the universe is found to be defined identically to the characteristic energy of a cosmological constant. Two independent methods are used to estimate the universe information content of ~10^91 bits, a value that provides an information energy total comparable to that of the dark energy. Information energy is also found to have a significantly negative equation of state parameter, w<-0.4, and thus exerts a negative pressure, similar to dark energy.

Parallel processing speed increase of the one-bit auto-correlation function in hardware

Recently, a serial implementation of the one-bit auto- and cross-correlation functions (ACF and CCF respectively) in a field programmable gate array (FPGA) has been developed, based on asynchronous delay elements and counters, known as the counterbased correlation. This paper proposes a method of parallelizing this otherwise serial process, offering significant improvements in the applicability of this approach to more types of ACF. Furthermore, the possibility of obtaining lag results from a parallel data sequence without first shifting the entire sequence has been realized, hence decreasing the number of clock cycles necessary for the calculation of the ACF. A synchronous design was preferred here for reasons of stability and portability, the technology of choice again being an FPGA. The advantages offered by the counterbased implementation in terms of device area usage and speed still apply. A practical implementation in the instrumentation of an upcoming space mission is also discussed.