VLBI studies of the solar-wind plasma irregularities at 18 and 92 CM wavelengths in 1994–1996

We discuss the capabilities of VLBI studies of irregularities of the solar-wind plasma using multi-element radio interferometric facilities. We analyze the data obtained during international VLBI experiments at decimeter wavelengths (92 and 18 cm) in 1994–1996 and supposed that the irregularities have a “stream” structure. The “streams” are strongly elongated in the solar-wind direction (longitudinal size of about a few hundred thousand kilometers) and have the transverse size of about 0.5–2.0 thousand kilometers. The irregularities inside a single “stream” are almost isotropic. We discuss the restrictions imposed on operation of decimeter VLBI systems due to effects of the interplanetary medium. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 43, No. 3, pp. 197–206, March, 2000     

Possibilities of VLBI observation of solar spike-like events

Modern theoretical and experimental investigations of energy release fragmentation in solar flares show the necessity of observations with high space and time resolution. In this paper, we analyze earlier interferometric observations of solar radio spikes and discuss the first results of the Radiophysical Research Institute of Nizhny Novgorod (NIRFI) in this field. We describe the NIRFI's receiving and analyzing equipment, which is part of the measuring complex for solarflare investigation with high space and time resolution and enables one to analyze the form of the interference signal and its amplitude spectrum with time and frequency resolutions of up to 16.7 sec and 100 Hz, respectively. The prospects for VLBI observation of solar flares with high space resolution are discussed.Radiophysical Research Institute, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 10, pp. 1046–1056, October, 1995.     

Radiointerferometric studies of the fine structure of supercompact extragalactic sources and space media in the decimeter wavelength range

We describe international VLBI experiments at decimeter wavelengths (92 and 18 cm) carried out in 1994–1997. These experiments were organized as a pre-lauch survey of space radio sources for the forthcoming Earth-space radio interferometer “Radioastron.” The experiments were aimed at determination of the list of the sources that can be used in future observations with the space-Earth interferometer, determination of the limits posed by the interplanetary medium on such observations, and study of the physical parameters of irregularities of the solar wind plasma. The first obtained results are reported. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 12, pp. 1127–1135, December 1999.     

大面积染料敏化太阳电池的实验研究

通过对大面积染料敏化太阳电池的实验研究，探讨了串联电阻对大面积染料敏化太阳电池光伏特性的影响问题，给出了解决这一问题的有效方法. 在此基础上制作的大面积条状电池(0.8cm×18cm)光电转换效率达到6.89%，而由此条状电池并联组成的大面积电池(15cm×20cm)的效率接近6%. 使得大面积染料敏化太阳电池的研究工作取得突破性进展，迈出了实用化的关键一步，为其工业化生产及商业化应用提供了理论和实验依据. 关键词： 大面积 染料敏化 太阳电池 串联电阻     

Millimeter-wave Receiver Optics for Korean VLBI Network

Over the past several years the millimeter wave VLBI (Very Long Baseline Interferometry) observations have been intensively performed. However phase fluctuation due to troposphere is one of the key issue in terms of degradation of sensitivity and limits imaging capability in millimeter wave VLBI observations. We describe the details of designed receiver optics for the Korean VLBI Network to calibrate tropospheric phase fluctuation for the millimeter wave VLBI observation. These optics guide beams from one position on sky to 22, 43, 86, and 129 GHz-band receivers simultaneously. Several topics, such as the design principles of imaging and power loss due to phase errors on common ellipsoidal mirrors are discussed.     

Measurement of the solar gravitational deflection of radio waves using geodetic very-long-baseline interferometry data, 1979-1999

We used very-long-baseline interferometry (VLBI) to measure the deflection by the Sun of radio waves emanating from distant compact radio sources. This bending is characterized in the parametrized post-Newtonian formalism by gamma, which is unity in general relativity. Using a large geodetic VLBI data set, we obtained gamma=0.9998(3)+/-0.0004(5) (estimated standard error). We found no systematic biases from our analysis of subgroups of data.     

From polarimetry to helicity: Studies of solar magnetic fields at the Huairou Solar Observing Station

In this paper, we briefly introduce the basic questions in the measurements of solar magnetic fields and the possible error sources due to the approximation of the theory of radiation transfer of spectral lines in the solar atmosphere. We introduce some basic research progress in magnetic field measurement at Huairou Solar Observing Station of National Astronomical Observatories,Chinese Academy of Sciences, especially concerning the non-potentiality in solar active regions, such as the magnetic shear,current and helicity. We also discuss some basic questions for the measurements of the magnetic fields and corresponding challenges for the future studies.     

超高精度的甚长基线干涉相位时延推导法及其在我国的应用前景

文章简要介绍了同波束甚长基线干涉(VLBI)观测法和相位时延推导法,报道了上海-乌鲁木齐基线的误差为0.0005m的差分相位时延的观测结果,介绍了"萤火1号"和"福布斯"探测器的同波束VLBI观测技术及正在研究的相位时延推定新方法,展望了超高精度的VLBI相位时延在中国深空探测中的应用前景.     

Broadband laser amplifier based on gas-phase dimer molecules pumped by the Sun

We report the design and experimental realization of a solar-pumped dimer gas-laser amplifier. The amplifying medium is Te(2) gas, which is capable of amplifying laser signals over a broad spectral range. A gain of 42% was measured at a wavelength of 632.8 nm. We also present studies of the material characteristics and a brief review of the study of other candidate materials for solar pumping.     

Thin-film polycrystalline Si solar cells on foreign substrates: film formation at intermediate temperatures (700–1300 °C)

We give an overview and analysis of research on thin-film polycrystalline Si solar cells on foreign substrates, with layers formed at intermediate temperatures (700–1300 °C), covering substrates, deposition techniques and solar cell processing. The main deposition techniques that have been investigated are solution growth (SG) and chemical vapour deposition (CVD). Insufficient nucleation on foreign substrates is an important problem with SG, which could be solved with appropriate surface preparation techniques and growth conditions. With CVD, continuous layers are achieved routinely, but the electronic quality of the material is usually very low. Solar cell performance appears to be limited by a very large recombination activity of grain boundaries. Improvement can be achieved reducing the grain boundary density and recombination activity, and experimental examples are given. Devices have been demonstrated with efficiencies up to 5.5%. PACS 73.40.Lq; 73.50.Gr; 84.60.It     

Results of theoretical and experimental studies of solar wind and active galactic nuclei on LFVN VLBI network using S2 recording system

We discuss the results of two sessions of observations at the Low-Frequency VLBI Network (LFVN), carried out in 1999 (INTAS99.4) and 2000 (INTAS00.3) at a wavelength of 18 cm using the S2 recording system and processed using the correlator system in Pentictone, Canada. In different configurations of the experiments on studying the solar wind and active galactic nuclei, the antennas at the following sites were employed: Medvezhji Ozera (RT-64, Special Engineering Bureau of Moscow Power Engineering Institute, Russia), Pushchino (RT-22, Pushchino Radio Astronomy Observatory, Russia), Hartebeesthoek (RT-25, South Africa), Noto (RT-32, Italy), Shanghai (RT-25, China), Pune (RT-45, India), Svetloe (RT-32, Institute of Applied Astronomy RAS, Russia). The work resulted in successful testing of the method of radio probing of the solar-wind plasma by radiation of extragalactic sources, supplemented with the method of radio interferometric reception. Spectral analysis of the obtained data allowed us to estimate the index of spatial spectrum of the electron number density.uctuations and the transfer velocity of the solar-wind inhomogeneities on the sounding path. We present and discuss the retrieved images of STA-102 quasar and the BL Lacertae object 1418+546 with millisecond angular resolution and demonstrate the results of modeling the structure of these sources. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 4, pp. 275–299, April 2007     

Electron injection dynamics in dye-sensitized semiconductor nanocrystalline films

We have summarized recent ultrafast spectroscopic studies on phenomena associated with dye-sensitization of semiconductor metal oxide nanoparticles, especially TiO₂ nanocrystalline film from a surface science perspective with a strong relation to mechanism of electron injection in dye-sensitized solar cells, which are attracting much interest from both viewpoints of pure science and applied science.A lot of chemical and physical processes are involved in this solar cell, such as light harvesting by molecules and nanostructures, interfacial electron transfer, charge migration in solid and electrolyte, degradation of the materials, and so on. Among them, the very primary process initiated by photoabsorption by sensitizing dye molecules; that is, electron injection from excited adsorbates into the conduction band of semiconductor metal oxides is significantly important, because this process must be 100% efficient with a minimum driving force for high current and voltage generation.We have first focused on details of experimental methods used in this research area, and then in the following Sections, have organized this review by concentrating on each parameter that influences dynamics of electron injection in dye-sensitized semiconductors. Finally we have emphasized it is important to measure actual DSSCs for the precise comparison between electron injection dynamics and device performance.     

Solar neutrino decay

We re-examine the neutrino decay solution to the solar neutrino problem in light of the new data from GALLEX II and Kamiokande III. We compare the experimental data with the solar models of Bahcall and Pinsonneault and Turck-Chieze and find that neutrino decay is ruled out as a solution to the solar neutrino problem at better than the 98% CL even when solar model uncertainties are taken into account.     

Spacecraft Doppler tracking with a VLBI antenna

Summary Accurate measurements of the Doppler shift of the Voyager 2 spacecraft (26 A. U.) have been performed in the period 23/7/88-12/8/88 with the 32m VLBI antenna at Medicina (BO). The device which allows the use of VLBI instrumentation for precision Doppler tracking is basically an open-loop receiver and is called digital tone extractor (DTE). Simultaneous measurements were performed at NASA's Deep Space Network (DSN) stations of the Madrid complex, using a different technique (closed loop). In the most interesting tracking configuration, the signal was transmitted inS-band (2.1 GHz) from the 70 m DSN station at Canberra (Australia), retransmitted back coherently from the spacecraft inX-band (8.4 GHz–19 W) and received 7h 6min later at Medicina and Madrid. The main purpose of the experiment was to test the capabilities of this new system and to characterize its performances. This taks has been successfully accomplished with the acquisition of high-quality data, which are presently under analysis. We plan also to compare and correlate the data with the ones acquired at Madrid stations, in order to separate out different noise contributions to the measured signal. The use of Medicina antenna as a listen-only station is planned for the gravitational wave experiment of the Ulysses spacecraft (ESA), in 1992. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

Applications of same-beam VLBI in the orbit determination of multi-spacecrafts in a lunar sample-return mission

Same-beam VLBI means that two spacecrafts with small separation angles that transmit multi-frequency signals specially designed are observed simultaneously through the main beam of receiving antennas. In same-beam VLBI,the differential phase delay between the two spacecrafts and the two receiving antennas can be obtained within a small error of several picoseconds. As a successful application,the short-arc orbit determination of several hours for Rstar and Vstar,which are two small sub-spacecrafts of SELENE,has been much improved by using the same-beam VLBI data together with the Doppler and range data. The long-arc orbit determination of several days has also been accomplished within an error of about 10 m with the same-beam VLBI data incorporated. These results show the value of the same-beam VLBI for the orbit determination of multi-spacecrafts. This paper introduces the same-beam VLBI and Doppler observations of SELENE and the orbit determination results. In addition,this paper introduces how to use the same-beam VLBI for a lunar sample-return mission,which usually consists of an orbiter,a lander and a return unit. The paper also offers the design for the onboard radio sources in the lunar sample-return mission,and introduces applications of S-band multi-frequency same-beam VLBI in lunar gravity exploration and applications during all stages in the position/orbit determinations such as orbiting,landing,sampling,ascending,and docking.     

Laser Sintering of a Porous TiO2 Film in Dye-Sensitized Solar Cells

We investigate the possibility of modifying the porous structure of TiO₂ films in dye-sensitized solar cells (DSSC) in its sintering by a pulsed Nd:YAG laser (wavelength 1064 nm) to improve their parameters and characteristics. Sintering at various pulse energies enabled a porosity within the range of 0.45 to 0.20. The efficiency of the energy conversion in experimental DSSC specimens with TiO₂ films sintered by an optimum laser-radiation pulse energy of 150 mJ was 20–25% higher than that of commercial solar cells.     

Closed-form expression for the current/ voltage characteristics of <Emphasis Type="Italic">pin</Emphasis> solar cells

A closed-form expression for the current–voltage relationship of pin diodes and pin solar cells is obtained. The model considers drift and diffusion currents, and assumes a uniform electric field in the intrinsic layer, equal diffusion lengths for electrons and holes and a homogeneous generation rate. We show that both drift and diffusion currents must be taken into account to describe the current over a wide range of applied voltage. The inclusion of both transport mechanisms results in diode ideality factors between 1.8 at low, and 1.2 at high applied voltages. Comparisons of current/voltage characteristics and solar cell output parameters obtained from our model with experimental data of thin-film silicon solar cells show that our model accurately explains the output characteristics of pin solar cells. PACS 84.60.Jt; 85.60.Bt     

Direct measurement of the 7Be solar neutrino flux with 192 days of borexino data

We report the direct measurement of the 7Be solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso. The interaction rate of the 0.862 MeV 7Be neutrinos is 49+/-3stat+/-4syst counts/(day.100 ton). The hypothesis of no oscillation for 7Be solar neutrinos is inconsistent with our measurement at the 4sigma C.L. Our result is the first direct measurement of the survival probability for solar nu(e) in the transition region between matter-enhanced and vacuum-driven oscillations. The measurement improves the experimental determination of the flux of 7Be, pp, and CNO solar nu(e), and the limit on the effective neutrino magnetic moment using solar neutrinos.     

On the variability of the transmission coefficient of the atmospheric optical window

Summary We use experimental data to show that the amplitudeA of the oscillations impressed upon upper atmospheric electrons by the electric field vectors of incident solar radiation increases with the solar energy wavelength λ over the visible spectrum. Calculations based upon experimental data show that the transmission coefficientT of the upper atmosphere for incident solar energy (say at intensityI ₀) also increases with λ over the visible spectrum, implying thatT increases withA over the latter range. Finally we show thatI ₀ ^1/2 λ² bears a positive linear relationship withT over the visible solar spectrum. The latter conclusion, which confirms theoretical results contained in a recent paper, is then used to show that the 100 000 year eccentricity cycle effectively causes a maximum change in the total solar energy reaching the lower atmosphere of approximately 4.5% which is enough to trigger an ice age.