High-resolution spectroscopic imaging of the Sun with a universal birefringent filter and a Fabry-Perot Interferometer

Summary We describe an optical device consisting of a Universal Birefringent Filter and a Fabry-Perot interferometer used in tandem to obtain monochromatic images of the Sun in the visible spectrum (between 4200 and 7000 ?). The spectral resolving power is about 300000 and the wavelength stability might reach 0.02 m? at 5000 ? (≈1.2 m/s) with an integration time of 1 s. The image is recorded by a CCD camera based on a Thomson THX31159 device with 512×512 square pixels 19 μm in size. A prototype of this instrument was tested at the G. B. Donati Solar Tower of the Arcetri Astrophysical Observatory by obtaining, at fixed time intervals, several series of full disk monochromatic images of the Sun at different wavelengths inside the Fe I 5905.7 ? photospheric line. In this paper we describe the instrument and its characteristics and we give an cccount of the preliminary results obtained by measuring the global velocity field on the solar photosphere. These results show that the instrument is well suited for global oscillation measurements. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

Preparation of a second station for the measurement of solar oscillations of low degree

Summary An observing station to detect low-degree global solar oscillations is already operational at Jet Propulsion Laboratory (Pasadena, CA-USA). In collaboration with Reparto Raggi Cosmici, I.F.S.I.-C.N.R., a second station for continuative measurements of such oscillations has recently been installed and successfully tested in Rome. The high transmission and stability of the magneto-optical filter (MOF) coupled with the lock-in amplifier technique allow analogic and real time detection of oscillation modes with a noise level of only a few cm/s. We show observing runs and estimates of the signal-to-noise ratio in time and frequency domains. Routine observations will establish whether the MOF sensitivity and stability is suitable to detect stellar oscillations. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

Solar probe: a rendezvous with the Sun

Summary A study has been promoted by NASA to evaluate the scientific return and the technological problems of a close-to-the-Sun mission (Solar Probe). It has come out that using current technology it is possible to deliver at 4 solar radii from the Sun's centre a scientific payload with such performances to allow a great improvement of our understanding of the coronal phenomena. The mission concept currently under study uses planetary encounters to reach the required orbit. The final orbit period is 2.5 years, the estimated mission duration about 9 years. The orbit inclination is such as to give the maximum coverage in terms of heliographic latitude. During the perihelion phases a conical structure shields the spacecraft from the intense solar radiation. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

An improved high-resolution solar reference spectrum for earth's atmosphere measurements in the ultraviolet, visible, and near infrared

We have developed an improved solar reference spectrum for use in the analysis of atmospheric spectra from vacuum wavelengths of 200.07 through 1000.99 nm. The spectrum is developed by combining high spectral resolution ground-based and balloon-based solar measurements with lower spectral resolution but higher accuracy irradiance information. The new reference spectrum replaces our previous reference spectrum, and its derivatives, for use in a number of physical applications for analysis of atmospheric spectra, including: wavelength calibration; determination of instrument transfer (slit) functions; Ring effect (Raman scattering) correction; and correction for spectral undersampling of atmospheric spectra, particularly those that are dilute in absorbers. The applicability includes measurements from the GOME, SCIAMACHY, OMI, and OMPS satellite instruments as well as aircraft-, balloon-, and ground-based measurements.     

Observations of energetic particles with EPAC on Ulysses in polar latitudes of the heliosphere

Summary Measurements with the EPAC energetic-charged-particle instrument aboard Ulysses show between −15° and −65° ions and, to some extent, also electrons apparently accelerated by shocks associated with a cororating interaction region (CIR) operating at low latitudes. Particles could have reached Ulysses along magnetic-field lines which connect to the shocks in the more distant heliosphere. Such connections evidently do not exist above −65°. Between the recurrent streams we find the underlying composition to be similar to that of the anomalous component of cosmic rays (ACR). One channel (ELH), sensitive also to high-energy protons (E>210 MeV), shows that, superimposed to the large-scale heliospheric modulation of galactic ions, a 26-day variation of the flux is observed. Such modulation is also observed for the ACR, in phase with the galactic particle modulation, but anticorrelated to the CIR-related low-energy particles. An estimate of the latitudinal and radial gradients of the galactic cosmic rays at 1 GV gives +0.4%/degree and −11%/AU, respectively. Paper presented at the Special Session on the Ulysses mission of the XXIV International Cosmic-Ray Conference, Rome, August 28–September 8, 1995.     

Polarimetry of small bodies of the solar system with large telescopes

During the last 10 years, the FORS instrument of the ESO very large telescope was regularly used to obtain broadband linear polarization measurements of small bodies of the solar system. In particular, FORS was the first (and so far unique) instrument that allowed us to explore polarimetrically objects of the solar system other than planets, moons, asteroids, and active comets. From 2002 to 2010, more than 150 h of telescope time were allocated for the observations of Centaurs, trans-Neptunian objects, and cometary nuclei. With a R magnitude between 16 and 21, these targets are probably the faintest objects of the solar system ever observed in polarimetric mode. In addition to these objects, polarimetric measurements were obtained for asteroids, active comets, Mars, the Saturn moon Iapetus, and the Moon earthshine. Here we present a review of these measurements, from the strategies adopted for the observations to the observational results.     

3D heliospheric simulations of cosmic rays in the light of Ulysses

Summary Recent Ulysses observations in the polar regions of the heliosphere have provided fundamental new insights into the modes of cosmic-ray transport in the heliosphere. Ulysses discovered variations in the magnetic field which are large enough to produce significant cosmic-ray effects, and which are consistent with a previous prediction. In addition to impeding the inward, radial diffusive and drift access of cosmic rays over the poles as discussed previously, the magnetic fluctuations imply a significantly larger latitudinal diffusion. These effects directly lead to both a much reduced latitudinal gradient and significant 27-day time variations near the pole. We conclude that the general picture of cosmic-ray transport and modulation developed over the past decade, with reasonable parameters, can account for most of the observed global, large-scale phenomena. Paper presented at the Special Session on the Ulysses mission of the XXIV International Cosmic-Ray Conference, Rome, August 28–September 8, 1995.     

A high-resolution spectroscopic study of the gamma radiation from the decay of96Nb

The decay of 24h⁹⁶Nb has been studied with a Ge(Li) spectrometer and with a Ge(Li)-NaI(Tl) coincidence spectrometer. A total of 27 gamma-ray transitions were observed, their energies and intensities measured. All but one of these have been incorporated into the level scheme of⁹⁶Mo. The level at 1,625.9 keV reported recently in (n _th, γ) work on⁹⁵Nb has also been observed through the decay of⁹⁶Nb. No experimental evidence has been found for previously proposed levels at 2,657 and 2,791 keV in⁹⁶Mo.     

太阳能与生物质能耦合供能系统的应用研究

介绍了太阳能与生物质能溴化锂吸收式制冷机的工作原理,分析了太阳能集热器及溴化锂制冷机组的热效率,利用生物质汽化炉余热弥补太阳能不稳定的缺陷,证明了利用清洁能源作为溴化锂吸收式中央空调热源问题的可行性。     

Dust in the planetary system: Dust interactions in space plasmas of the solar system

Cosmic dust particles are small solid objects observed in the solar planetary system and in many astronomical objects like the surrounding of stars, the interstellar and even the intergalactic medium. In the solar system the dust is best observed and most often found within the region of the orbits of terrestrial planets where the dust interactions and dynamics are observed directly from spacecraft. Dust is observed in space near Earth and also enters the atmosphere of the Earth where it takes part in physical and chemical processes. Hence space offers a laboratory to study dust–plasma interactions and dust dynamics. A recent example is the observation of nanodust of sizes smaller than 10 nm. We outline the theoretical considerations on which our knowledge of dust electric charges in space plasmas are founded. We discuss the dynamics of the dust particles and show how the small charged particles are accelerated by the solar wind that carries a magnetic field. Finally, as examples for the space observation of cosmic dust interactions, we describe the first detection of fast nanodust in the solar wind near Earth orbit and the first bi-static observations of PMSE, the radar echoes that are observed in the Earth ionosphere in the presence of charged dust.     

A high-resolution 19F NMR spectroscopic study of barium fluorozirconate glasses and related crystals

Fluorozirconate glasses have attracted considerable attention not only for their transparency in the infrared, but also due to their high fluorine ion conductivities and extreme fragility in the viscosity-temperature relationship. We report on structural studies of binary BaF2-ZrF4 glasses with 58-78 mol% ZrF4 using high-resolution magic-angle-spinning 19F NMR. High-speed 19F MAS NMR allows us to resolve at least three unique fluorine environments in these binary glasses. These fluorine environments are attributed to one type of bridging fluorine, between corner-sharing Zr-F coordination polyhedra, and two types of non-bridging fluorine (NBF), one of which is bonded to one Zr and one Ba atom while the other is bonded to one Zr and two Ba atoms. The concentration of the first type of NBF increases with decreasing ZrF4 concentration, while that of the second type is essentially independent of glass composition. These assignments have been made on the basis of detailed 19F NMR studies of a wide variety of crystalline fluorozirconates with known crystal structures. A comparison between the glass and crystal 19F NMR spectra rules out any significant concentration of edge-shared Zr-F polyhedra in these binary glasses. The Zr atoms in all glasses are found to be coordinated to approximately 7.8+/-0.2F atoms.     

The ACE-FTS atlas of the infrared solar spectrum

The ACE-FTS is a space-borne Fourier transform spectrometer onboard SCISAT-1. The satellite was launched in August 2003 and since February 2004 the ACE-FTS has been performing solar occultation measurements in order to infer the chemical composition of the terrestrial atmosphere. The individual spectra recorded at the highest limb tangent altitudes (above 160 km) are by definition “high sun” spectra and contain no atmospheric contribution. In this work, an empirical solar spectrum covering the 700 to 4430 cm⁻¹ spectral range has been constructed from an average of 224,782 individual ACE-FTS solar spectra. Line assignments have been made for about 12,000 lines. The spectrum and two line lists are provided in the supplemental material attached to this work. Due to the excellent noise level achieved in the ACE-FTS solar atlas presented here, numerous weak absorption features are assigned which were not detectable in the ATMOS solar observations.     

Optical inspection system with tunable exposure unit for micro-crack detection in solar wafers

Micro-cracks are a major cause of wafer breakage in the solar wafer manufacturing process. Furthermore, the existence of micro-cracks may lead to electrical failure in the post-fabrication inspection of solar cells and solar modules. Thus, the reliable detection of micro-cracks is an important concern in the photovoltaic industry. Accordingly, the present study proposes a novel micro-crack inspection system comprising a near infrared light source, a CCD camera and a tunable exposure unit. In the proposed system, the intensity of the light transmitted through the wafer is sensed by a photodetector and the exposure time of the CCD camera is tuned accordingly in order to maximize the contrast of the CCD image; thereby improving the performance of the crack detection process. The experimental results show that the proposed system enables the reliable detection of micro-cracks in solar wafers with a thickness of up to 240 μm within 1 s. In other words, the system provides an ideal solution for on-line micro-crack inspection applications in the photovoltaic industry.     

A solar concentrator with two reflection mirrors designed by using a ray tracing method

Solar concentrators with two reflection mirrors are numerically designed by using a ray-tracing method to obtain higher concentration ratio when the concentrator tracing error is existed. The primary reflection mirror adopts paraboloidal mirror; the secondary mirror adopts hyperboloidal or ellipsoidal mirror. The optimal designed shape parameters for hyperboloidal and ellipsoidal cases are obtained, respectively. It is found that, when the concentrator tracing errors are 0°, 0.5° and 1°, the concentration ratios for hyperboloidal case are about 5837, 1954 and 1127 at f-number₁=0.22 and NA₂=0.62 and the one for ellipsoidal case are about 5860, 1993 and 1193 at f-number₁=0.25 and NA₂=0.62, respectively. Obviously, the concentrator with the ellipsoidal mirror is slightly better than the one with the hyperboloidal mirror.     

A study on the aluminum fire-through to a-SiNx:H thin film for crystalline solar cells

The relationship between aluminum fire-through and the properties of a-SiN_x:H thin films was investigated to aid their use as dielectric layers in rear side and front passivation layers in crystalline solar cells. Aluminum fire-through was shown to depend on the refractive index and the deposition rate of the films.Refractive index, density and deposition rate increased with increasing SiH₄/NH₃ ratio, while the etching rate decreased. Aluminum fire-through occurred in a sample of refractive index 2.0 during fast deposition but not when the deposition rate was slow. Aluminum fire-through occurred during extended firing, despite it not occurring during normal firing by RTP. The results of this work demonstrate that refractive index was the major determinant of aluminum fire-through, and that the aluminum and the a-SiN_x:H thin film reacted immediately at the beginning of firing at a rate determined by the deposition rate.     

太阳能两级喷射式制冷系统性能的模拟及其分析

讨论了一种新型的太阳能制冷系统——带回热器的太阳能两级喷射式制冷系统.该系统最大的特点是将两个喷射器串联在一起,以提高整个太阳能制冷系统的性能系数.分别采用R134a、R152a、R245ca和R227ea为制冷工质下系统性能系数COP随两级间总压比分配度不同的变化关系.这四种制冷剂的两级压缩比的变化对总喷射系数的影响各有不同,并提出了气体喷射器的总压缩比1.2-2.8之间两级压缩比的不均匀分配原则.     

Evolution of the Alfvénic correlation in the solar wind

Summary The radial evolution of Alfvénic correlation is such that its value decreases with increasing heliocentric distance. So far this behaviour has been interpreted as an increase in the local production of ?inward? modes interacting destructively with the ?outward? modes. This work, which deals with largescale turbulence, shows that local generation phenomena are not commonly found in the solar wind and that the Alfvénic character of the fluctuations mainly depend on the ?outward? modes alone. The interaction of these modes with density and/or magnetic-field structures convected by the wind causes their destruction and a consequent depletion of the Alfvénic correlation. The same effect would be obtained if ?inward? modes were really present. Our conclusions are that large-scale ?inward? modes are the spectral counterpart of non-propagating field and plasma structures convected by the solar wind and identified as both compression regions and pressure balance structures. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

Nonlinear oblique propagation of magnetohydrodynamic waves in the solar wind

Summary Oblique propagating magnetohydrodynamic waves with various wave forms and amplitudes are observed both at the Earth's foreshock and at comets. The possibility of interpreting some observational results in terms of nonlinear evolution of one- and two-dimensional hydromagnetic waves is investigated. For this purpose both analytical and numerical techniques are employed. It is found that an initial monochromatic wave changes its polarization giving origin to magnetosonic shocks and rotational discontinuities; the time evolution of density-magnetic-field correlation is studied, as a function of the plasma parameters and of the propagation angle. In the two-dimensional case both a transverse instability and a self-focusing effect may take place. Moreover, a two-dimensional magnetosonic solution is found, in which the density fluctuations are driven by the total pressure fluctuation as in a one-dimensional simple wave. These theoretical predictions compare well with the features observed in the solar-wind waves. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.