Lightweight (AlGaAs)GaAs/CuInSe2 tandem junction solarcells for space applications

Mechanically stacked tandem cells consisting of GaAs thin-film upper cells and CuInSe₂ thin-film lower cells have been developed to meet the increasing power needs projected for future spacecraft. The authors report the fabrication of the first highly efficient lightweight GaAs/CuInSe₂ tandem cell on a 2-mil thick substrate, update recent performance improvements in thin-film GaAs/CuInSe₂ tandem cells, and discuss their application to space power systems. The efficiency of 4-cm² cells has improved to 21.6% AM0, the highest ever reported for a thin-film photovoltaic cell. Lightweight 4-cm² tandem cells have been successfully fabricated with efficiencies as high as 20.8%. These cells weighed about 180 mg without optimized substrate trimming. Radiation and operating temperature effects on GaAs/CuInSe₂ tandem cells are also discussed, and an interconnect scheme to form a voltage-matched string is described     

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.     

InAsP cells for solar thermophotovoltaic applications

High temperature wide band gap InAsP cells have been specifically designed and fabricated for operating temperatures up 250°C to match with selective emitters operating near 1 μm in a TPV system. An important assumption is that the emitters can be heated up to the range of 1400 K to 2000 K by either solar concentrators or some other heat source. The efficiency of a selective emitter, which can be selected depending on the emitter operating temperatures, will be significantly higher than either a blackbody or a graybody emitter. The key for the TPV success is that the match between the band gap and selective emission must occur at the cell operating temperature. An appropriate cell band gap needs to be carefully selected; so when the band gap shrinks at the operating temperature, the desired match can be achieved. In this paper, two types of InAsP cells were investigated for this concept. The performance of these cells at elevated temperature and energy conversion efficiency are reported in this paper     

One geometrical idea for solar cells

A single analysis shows that it may be possible to take advantage of a geometrical property of one of the regular polygons with which it is possible make a tesselation of a given area with better efficiency     

Spaceflight testing of solar cells and concentrating arrays

The following topics are dealt with: new solar cell performance developments; calibration related developments; solar array concentrator; solar cell efficiency; nighttime power generation     

Ultra-lightweight space power from hybrid thin-film solar cells

The development of hybrid inorganic/organic thin-film solar cells on flexible, lightweight, space-qualified, durable substrates provides an attractive solution for space power generation with high mass specific power (W/kg). The high-volume, low-cost fabrication potential of organic cells will allow for square miles of solar cell production at one-tenth the cost of conventional inorganic materials. Plastic solar cells take a minimum of storage space and can be inflated or unrolled for deployment. We explore a cross-section of NASA in-house and sponsored research efforts that aim to provide new hybrid technologies that include both inorganic and polymer materials as active and substrate materials. For NASA applications, any solar cell or array technology must not only meet weight and AMO efficiency goals, but also must be durable enough to survive launch and space environments. Also, balance of system technologies must be developed to take advantage of ultra-lightweight solar arrays in power generation systems.     

Large area solar cells for future space power systems

Space silicon solar cell technology has matured to the extent that large-area planar silicon cells can be fabricated in sizes up to 8 cm×8 cm with efficiencies up to approximately 15%. In order to achieve substantially higher efficiencies, cells based on GaAs are required. It is shown that, subject to certain boundary conditions, the efficiency of GaAs/Ge cells can reach 24% when used in the dual-junction configuration or approximately 19.5% if the Ge substrate is passive. The electrooptical properties of these cells are reviewed, and prospects for achieving these efficiency goals are presented. Experimental performance data are given     

The space performance of silicon vertical junction solar cells onthe LIPS-III satellite

The authors present the preliminary analysis and results of a space experiment to evaluate the performance of a new generation of silicon vertical junction solar cells and three adhesives for attaching coverglass to the solar cells. Two of the adhesives are used for the first time in coverglass applications in the space environment. The SOLAREX vertical junction solar cells, which are of 10-Ω-cm silicon with back surface fields (BSFs) and back surface reflectors (BSRs) are compared to SOLAREX planar junction cells, also of 10-Ω-cm, BSF, BSR silicon. The results up to 386 days in space indicate that the two types of solar cell show about the same degradation rate in power output. There are no significant differences at this point in the performances of the three different adhesives     

Interdisciplinary summary of solar/interplanetary events during August 1972

The solar/interplanetary events in early August 1972 are summarized in Section 1 (Introduction), Section 2 (August 1972 Events in the Solar Cycle 20), Section 3 (Evolution of Solar Active Region: McMath region No. 11976 and its flare-activity), Section 4 (Radio, X-ray, and Proton Characteristics of Four Major Solar Flares: F-1 at 0316 UT on 2 August, F-2 at 1958 UT on 2 August, F-3 at 0626 UT on 4 August, and F-4 at 1522 UT on 7 August), Section 5 (Interplanetary Shock Waves: observations of the shock waves generated from the four major solar flares at several points in interplanetary space, the Earth, Pioneer-9, Pioneer-10, etc.; interplanetary scintillations; shock trajectories in the heliosphere), Section 6 (Variations of Solar and Galactic Cosmic Rays: four solar proton events observed in the vicinity of the earth and at the Pioneer-9 location in the course of interplanetary disturbances; Forbush decreases of cosmic ray intensity; the spikeshaped variation in solar and galactic cosmic rays on 5 August), and Section 7 (Conclusions).     

Mechanical properties of multi-scale germanium specimens from space solar cells under electron irradiation

During long-term service in space, Gallium Arsenide(GaAs) solar cells are directly exposed to electron irradiation which usually causes a dramatic decrease in their performance. In the multilayer structure of solar cells, the germanium(Ge) layer occupies the majority of the thickness as the substrate. Due to the intrinsic brittleness of semiconductor material, there exist various defects during the preparation and assembly of solar cells, the influences of which tend to be intensified by the irr...     

A solar extreme ultraviolet telescope and spectrograph for Shuttle/Spacelab

An instrument for advanced studies of the solar corona is described. Its optical system provides nearly stigmatic imaging of selected portions of the Sun over the spectral range from 22.5 to 44.0 nm. Both spectroheliograms and emission line profiles of coronal features will be obtained over a wide range of coronal temperatures.Proceedings of the Conference Solar Physics from Space, held at the Swiss Federal Institute of Technology Zurich (ETHZ), 11–14 November 1980.This paper was presented at the conference by U. Feldman.     

太阳能火箭发动机吸热/推力室流场及性能计算

首先对某大型太阳能火箭发动机(Solar Thermal Propulsion:STP)的实验情况,进行了结构分析和基本实验条件估算.然后利用FLUENT计算软件,采用等壁温模型,对其吸热/推力室的内部流动、传 热情况,以及STP的性能特征等进行了计算,计算结果与实验数据一致,这对STP的设计有重要的指导意义.     

Kinetic properties of heavy ions in the solar wind from SWICS/Ulysses

The kinetic properties of heavy ions in the solar wind are known to behave in a well organized way under most solar wind flow conditions: Their speeds are all equal and faster than that of hydrogen by about the local Alfvén speed, and their kinetic temperatures are proportional to their mass. The simplicity of these properties points to a straightforward physical interpretation; wave-particle interactions with Alfvén waves are the probable cause. With the SWICS sensor on board Ulysses, it is now possible to investigate the kinetic properties of many more ion species than before. Furthermore, the transition of Ulysses into the fast stream emanating from the south polar coronal hole since 1992 allows us to study these properties both in the slow, interstream solar wind, as well as in an unambiguously identified fast stream. We present data from SWICS/Ulysses on the dominant ions of He, C, O, Ne, and Mg. As a result we find that, both in the slow wind and in fast streams, the isotachic property is obeyed even better than it could be determined by the ICI instrument on ISEE-3. The mass proportionality ofT _kin is also shown to hold for these ions, including the newly identified C and Mg.     

Interaction of non-perpendicular/parallel solar wind shock waves with the earth's magnetosphere

The interaction of travelling interplanetary shock waves with the bow shock-magnetosphere system is considered. We consider the general case when the interplanetary magnetic field is oblique to the Sun-planetary axis, thus, the interplanetary shock is neither parallel nor perpendicular. We find that an ensemble of shocks are produced after the interaction for a representative range of shock Mach numbers. First, we find that the system S ₊ R _– CS _– S ₊ appears after the collision of travelling fast shock waves S ₊ (Mach number M = 2 to 7) with the bow shock. Here, S _– and R _– represent the slow shock wave and slow rarefaction wave, and C represents the contact surface. It is shown that in the presence of an interplanetary field that is inclined by 45° to the radial solar wind velocity vector, the waves R _– and S _– are weak waves and, to the first degree of approximation, the situation is similar to the previously studied normal perpendicular case. The configuration, R ₊ C _m S _– S ₊ or R ₊ C _m R _– S ₊ where C _m is the magnetopause, appears as the result of the fast shock wave's collision with the magnetopause. In this case the waves S _– and R _– are weak. The fast rarefaction wave reflected from the magnetosphere is developed similar to the case for the collision of a perpendicular shock. The shock wave intensity is varied for Mach numbers from 2 to 10. Thus, in the limits of the first approximation, the validity of the one-dimensional consideration of the nonstationary interaction of travelling interplanetary shock waves with the bow shock-magnetosphere system is proved. The appearance of the fast rarefaction wave, R ₄, decreasing the pressure on the magnetosphere of the Earth after the abrupt shock-like contraction, is proved. A possible geomagnetic effect during the global perturbation of the SSC or SI⁺ type is discussed.An invited paper presented at STIP Workshop on Shock Waves in the Solar Corona and Interplanetary Space, 15–19 June, 1980, Smolenice, Czechoslovakia.     

Total solar irradiance measurements by ERB/Nimbus-7. A review of nine years

The advent of reliable extraterrestrial solar irradiance measurements from satellites has supplied the impetus for new research in solar physics and solar-terrestrial relationships. The records for the principal experiments now extend beyond nine years. The Nimbus-7 measurements began in November 1978 and the Solar Maximum Mission (SMM) results started in February 1980. Both the ERB experiment of Nimbus-7 and the ACRIM experiment of SMM are still operational as of this writing (June 1988). We describe the nine-year Nimbus-7 total solar irradiance data set and compare it with similar data sets from the SMM and other satellite solar monitoring programs. Long-term downward trends of less than 0.02 % per year had been noted during the decaying portion of solar cycle 21 with indications that a leveling off and possible reversal of the trend was being experienced as we enter the new cycle. It had been demonstrated that fluctuations in the data over shorter periods corresponded to solar activity, from a primary discovery of irradiance depletions in times of building large sunspot groups to more subtle effects on the scale of solar rotation. Studies of the frequency spectra of the measurements have advanced the interest in helioseismology or mode analysis. Studies of photospheric activity have advanced by modelling of the sunspot blocking and photospheric brightening versus the measured irradiance. The theories are being extended to longer time-scales which indicate that solar irradiance is higher near solar cycle maximum, as defined by activity, and somewhat lower during the period between cycles. While measurements of total solar irradiance, the solar constant, alone cannot be employed to answer all of the questions of solar physics or helioclimatology, these long-term, high-precision data sets are valuable to both disciplines. The continuation of such measurements to more meaningful, longer time-scales should have a high priority in the international space community.     

轻小型太阳能/氢能无人机发展综述

轻小型无人机（UAV）在军民领域都有着广泛的用途,电动无人机由于其振动低、无污染、无排放等优势,已经成为无人机领域的发展热点。为了提高轻小型电动无人机的航时,清洁、高能量密度的太阳能和氢能成为非常可行的技术途径之一。本文总结了轻小型太阳能、氢能无人机的发展历程;梳理了相关的关键技术,并对太阳能、氢能无人机的总体设计方法和能源动力系统的发展进行了较为深入的探讨;最后,展望了该类无人机的发展趋势,并对所面临的挑战进行了预测。     

Ulysses-Voyager study of energetic particles associated with the intense solar activity of March/June 1991

The intense solar activity centered in March and June 1991 produced some of the largest interplanetary disturbances over the past several solar cycles. For these events the Ulysses EPAC energetic particle observations near 3 AU are compared with those of the Voyager 2 CRS experiment near 35 AU. At Voyager 2 there is a single long-lived event extending over a period of some 6 months while the Ulysses data shows the imprint of individual events as well as the formative stages of the longer lived structure. The average intensity gradient is –17% AU between the 2 spacecraft. At both locations the energy spectra can be represented by an exponential in momentum. The characteristic momentum for protons, (P_o)_H is on the average 4–5 times larger at 35 AU than at 3 AU and there is a significant change in the (P_o)_He/(P_o)_H ratio. However the average H to He ratio is in the range 20–25 for both sets of measurements.     

An improved numerical method for constructing Halo/Lissajous orbits in a full solar system model

An improved numerical method that can construct Halo/Lissajous orbits in the vicinity of collinear libration points in a full solar system model is investigated. A full solar system gravitational model in the geocentric rotating coordinate system with a clear presentation of the angular velocity relative to the inertial coordinate system is proposed. An alternative way to determine patch points in the multiple shooting method is provided based on a dynamical analysis with Poincare′sections. By employing the new patch points and sequential quadratic programming, Halo orbits for L_1, L_2, and L_3 points as well as Lissajous orbits for L_1 and L_2 points in the EarthMoon system are generated with the proposed full solar system gravitational model to verify the effectiveness of the proposed method.     

Magnetic turbulence at the magnetopause, a key problem for understanding the solar wind/ magnetosphere exchanges

According to ideal MHD, the magnetopause boundary should split the terrestrial environment in two disconnected domains: outside, the solar wind (including its shocked part, the magnetosheath), and inside, the magnetosphere. This view is at variance with the experimental data, which show that the magnetopause is not tight and that a net transfer of matter exists from the solar wind to the magnetosphere; it implies that the frozen-in condition must break down on the magnetopause, either over the whole boundary or at some points. In the absence of ordinary collisions, only short scale phenomena (temporal and/or spatial) can be invoked to explain this breakdown, and the best candidates in this respect appear to be the ULF magnetic fluctuations which show very strong amplitudes in the vicinity of the magnetopause boundary. It has been shown that these fluctuations are likely to originate in the magnetosheath, probably downstream of the quasi-parallel shock region, and that they can get amplified by a propagation effect when crossing the magnetopause. When studying the propagation across the magnetopause boundary, several effects are to be taken into account simultaneously to get reliable results: the magnetopause density gradient, the temperature effects, and the magnetic field rotation can be introduced while remaining in the framework of ideal MHD. In these conditions, the magnetopause amplification has been interpreted in term of Alfvén and slow resonances occurring in the layer. When, in addition, one takes the ion inertia effects into account, by the way of the Hall-MHD equations, the result appears drastically different: no resonance occurs, but a strong Alfvén wave can be trapped in the boundary between the point where it is converted from the incident wave and the point where it stops propagating back, i.e., the point where k _\|=0, which can exist thanks to the magnetic field rotation. This effect can bring about a new interpretation to the magnetopause transfers, since the Hall effect can allow reconnection near this particular point. The plasma transfer through the magnetopause could then be interpreted in terms of a reconnection mechanism directly driven by the magnetosheath turbulence, which is permanent, rather than due to any local instability of the boundary, for instance of the tearing type, which should be subject to an instability threshold and thus, as far as it exists, more sporadic.     

Tandem solar cells with 31% (AM0) and 37% (AM1.5D) energyconversion efficiencies

The authors demonstrate that the efficiency of GaAs satellite solar cells can be increased to 31% (AM0) with two straightforward modifications. First, the wire grid reflection losses on the GaAs cell can be eliminated by attaching and aligning a thin grooved cover slide. The grooves in this cover slide deflect the incident light rays away from the wire grid lines into the cell active area, increasing the efficiency from 22% to 24%. The second modification involves making the GaAs cell transparent to the infrared energy that normally is wasted and then placing an infrared sensitive GaSb booster cell behind the GaAs cell. This increases the AM0 solar energy conversion efficiency from 24% to 31%. The GaAs/GaSb tandem solar cells have conversion efficiencies of 37% if used for terrestrial (AM1.5) rather than space (AM0) solar electric power systems, high enough that utility-scale solar electric power may someday be economical