Ultra triple-junction high-efficiency solar cells

Solar cells suitable for the space environment must combine high-efficiency, high energy density, and radiation hardness in a manufacturable design. As improvement in one performance parameter usually results in degradation in one or more of the remaining parameters, careful optimization is required to enhance overall performance. The ultra triple-junction cell developed builds upon the established success of the fully qualified improved triple-junction cell currently in production. In the ultra triple-junction cell configuration, improved robustness and efficiency after radiation exposure augment a cell design expected to deliver 28% beginning-of-life efficiency in production.     

Discrete energy release in microwave emission in the preflare stage

Examples of solar microwave precursors and estimates of their energetic characteristics are discussed based on spectral investigations of the preflare activity.     

Ionization and recombination processes determining plasma density at the initial stage of artificial cloud injection

The initial reduction of the electron density after the injection explosion is shown to be associated with recombination at the adiabatic cooling under the cloud expansion. Primordial thermal ions can disappear in triple collisions almost entirely. Nevertheless, a minor amount of ions is conserved due to the freezing effect. The further rapid increase in the electron concentration may be attributed to the secondary ionization process. It is shown that the cumulative electronic ionization can account for the observed electron density elevation. The modified two-stream instability can provide a longitudinal (anomalous) resistance for the longitudinal electric field required for an avalanche. The electric field and longitudinal currents arise owing to the polarization with ions entrained by the neutral gas across the magnetic field and magnetized electrons moving along the field.     

Nature's efficient energy production, storage, and data processing

Converting the solar energy received on the surface of the Earth has not been practical with heat engines because of the low density of this energy. On a clear bright day in the summer, the sun generally delivers less than 80 W per square foot. Also, heat engines are prohibited from exceeding the Carnot-cycle efficiency limit. On the other hand, plants perform their energy conversion electrochemically, and, hence, are not limited by the Carnot-cycle. They use solar energy to produce useful fuels that range from corn-cobs and maple syrup to pitch and firewood. However, they have an extremely complicated process control that uses blue and red parts of the visible solar spectrum to extract hydrogen from water and carbon from carbon dioxide to make hydrocarbons. They do not need precious-metal catalysts; however they run complex data processing programs in which stored instructions control electrochemical reactions and also cause growth and production of needed products to occur when needed.     

PWM full-bridge converter with natural input power factor correction

A pulsewidth modulated (PWM) full-bridge converter that simultaneously performs input power factor correction (PFC) and DC-DC conversion is proposed. The converter is the same as the standard voltage-fed PWM full-bridge converter with a diode-bridge low-pass filter front end, but with a slight modification that results in an improvement in power factor that is sufficient to satisfy the EN61000-3-2 requirements for electrical equipment. The operation of the converter is explained and analyzed, and the results of the analysis are used to determine the converter's steady-state characteristics, which are discussed in detail. A design procedure for the selection of components is then derived and demonstrated with an example. The feasibility of the converter and its ability to satisfy EN61000-3-2 requirements on electrical equipment is shown with results obtained from an experimental prototype.     

Observations of Magnetospheric Waves and their Relation to Precipitation

Magnetospheric wave observations are discussed from the viewpoint of their potential importance for precipitation of charged particles into the auroral zones. While wave processes are a fundamental part of magnetospheric plasma physics, occurring most of the time in most of the magnetospheric regions, their direct role in and relative importance for auroral precipitation are not easy to assess. The role of the waves varies from one spatial region to another and is very different for electrons and ions. Furthermore, the distinction between wave processes and other precipitation mechanisms is not at all straightforward. This review focuses on four main topics: The problem of diffuse electron precipitation, the recent surprise on the detailed structure of broad-banded electrostatic noise in the plasma sheet boundary layer, ion precipitation through electromagnetic ion cyclotron waves, and the role of low-altitude waves in precipitation. It is concluded that, while the observational status of high-altitude ion cyclotron waves is reasonably good, in most areas more thorough studies of existing data as well as refined observations are very much needed. Successful observational studies are to be carried out jointly with theoretical work as well as with studies on the large-scale context of the often localized wave processes. This is especially important when interests are moving toward more nonlinear phenomena, such as shocks, double layers, or strong quasi-static gradients, where a strict adherence to classical wave concepts is becoming more and more diffuse and less motivated.     

Radiation biodosimetry: applications for spaceflight.

The multiparametric dosimetry system that we are developing for medical radiological defense applications could be adapted for spaceflight environments. The system complements the internationally accepted personnel dosimeters and cytogenetic analysis of chromosome aberrations, considered the best means of documenting radiation doses for health records. Our system consists of a portable hematology analyzer, molecular biodosimetry using nucleic acid and antigen-based diagnostic equipment, and a dose assessment management software application. A dry-capillary tube reagent-based centrifuge blood cell counter (QBC Autoread Plus, Becton [correction of Beckon] Dickinson Bioscience) measures peripheral blood lymphocytes and monocytes, which could determine radiation dose based on the kinetics of blood cell depletion. Molecular biomarkers for ionizing radiation exposure (gene expression changes, blood proteins) can be measured in real time using such diagnostic detection technologies as miniaturized nucleic acid sequences and antigen-based biosensors, but they require validation of dose-dependent targets and development of optimized protocols and analysis systems. The Biodosimetry Assessment Tool, a software application, calculates radiation dose based on a patient's physical signs and symptoms and blood cell count analysis. It also annotates location of personnel dosimeters, displays a summary of a patient's dosimetric information to healthcare professionals, and archives the data for further use. These radiation assessment diagnostic technologies can have dual-use applications supporting general medical-related care.     

National paper of the Russian Federation

Despite its straightened circumstances and doubts about how much political support it receives, Russia's space programme continues — and continues to plan for new activities and applications. This edited version of the National Paper of the Russian Federation, presented at Unispace III in July 1999, details some of the country's major achievements in space in recent years and sets out the main areas it intends to pursue for the early twentieth-first century. While emphasis is placed on communications, remote sensing, navigation and space science, the commitment to manned flight remains.     

Population dynamics of transgenic microorganisms in the different microecosystem conditions.

The role of key environmental factors in adaptation of spore-forming and non-spore-forming transgenic microorganisms (TM) have been studied in model ecosystems. Model TM Escherichia coli Z905 (bearing plasmid genes of bacterial luminescence Ap (r) Lux+) has been found to have a higher adaptation potential than TM Bacillus subtilis 2335/105 (bearing genes of human alpha 2-interferon Km (r) Inf+), planned for employment as a living vaccine under varying environmental conditions. Effects of abiotic factors on migration of natural and recombinant plasmids between microorganisms under model ecosystem conditions has been estimated. The transgenic microorganisms with low copy number survived better under introduction conditions in the microcosms studied. This trend has been shown to be independent of the microcosm type and its complexity. Grant numbers: 99-04-96017, 25, 00-07-9011.