Kinetic Physics of the Solar Corona and Solar Wind

Directory of Open Access Journals (Sweden)

Marsch Eckart

2006-07-01

Full Text Available Kinetic plasma physics of the solar corona and solar wind are reviewed with emphasis on the theoretical understanding of the in situ measurements of solar wind particles and waves, as well as on the remote-sensing observations of the solar corona made by means of ultraviolet spectroscopy and imaging. In order to explain coronal and interplanetary heating, the microphysics of the dissipation of various forms of mechanical, electric and magnetic energy at small scales (e.g., contained in plasma waves, turbulences or non-uniform flows must be addressed. We therefore scrutinise the basic assumptions underlying the classical transport theory and the related collisional heating rates, and also describe alternatives associated with wave-particle interactions. We elucidate the kinetic aspects of heating the solar corona and interplanetary plasma through Landau- and cyclotron-resonant damping of plasma waves, and analyse in detail wave absorption and micro instabilities. Important aspects (virtues and limitations of fluid models, either single- and multi-species or magnetohydrodynamic and multi-moment models, for coronal heating and solar wind acceleration are critically discussed. Also, kinetic model results which were recently obtained by numerically solving the Vlasov–Boltzmann equation in a coronal funnel and hole are presented. Promising areas and perspectives for future research are outlined finally.

Magnetic Pumping as a Source of Particle Heating and Power-law Distributions in the Solar Wind

Science.gov (United States)

Lichko, E.; Egedal, J.; Daughton, W.; Kasper, J.

2017-12-01

Based on the rate of expansion of the solar wind, the plasma should cool rapidly as a function of distance to the Sun. Observations show this is not the case. In this work, a magnetic pumping model is developed as a possible explanation for the heating and the generation of power-law distribution functions observed in the solar wind plasma. Most previous studies in this area focus on the role that the dissipation of turbulent energy on microscopic kinetic scales plays in the overall heating of the plasma. However, with magnetic pumping, particles are energized by the largest-scale turbulent fluctuations, thus bypassing the energy cascade. In contrast to other models, we include the pressure anisotropy term, providing a channel for the large-scale fluctuations to heat the plasma directly. A complete set of coupled differential equations describing the evolution, and energization, of the distribution function are derived, as well as an approximate closed-form solution. Numerical simulations using the VPIC kinetic code are applied to verify the model’s analytical predictions. The results of the model for realistic solar wind scenario are computed, where thermal streaming of particles are important for generating a phase shift between the magnetic perturbations and the pressure anisotropy. In turn, averaged over a pump cycle, the phase shift permits mechanical work to be converted directly to heat in the plasma. The results of this scenario show that magnetic pumping may account for a significant portion of the solar wind energization.

Heating and Acceleration of Solar Wind Ions by Turbulent Wave Spectrum in Inhomogeneous Expanding Plasma

Science.gov (United States)

Ofman, Leon; Ozak, Nataly; Vinas, Adolfo F.

2016-01-01

Near the Sun (plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super- Alfvenic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.

Weather-power station. Solar energy, wind energy, water energy

Energy Technology Data Exchange (ETDEWEB)

Schatta, M

1975-10-02

A combined power station is described, which enables one to convert solar energy and wind energy into other forms of energy. The plant consists of a water-filled boiler, in which solar energy heats the water by concentration, solar cells, and finally wind rotors, which transform wind energy into electrical energy. The transformed energy is partly available as steam heat, partly as mechanical or electrical energy. The plant can be used for supplying heating systems or electrolysis equipment. Finally, by incorporating suitable motors, a mobile version of the system can be produced.

THE NEW HORIZONS SOLAR WIND AROUND PLUTO (SWAP) OBSERVATIONS OF THE SOLAR WIND FROM 11–33 au

Energy Technology Data Exchange (ETDEWEB)

Elliott, H. A.; McComas, D. J.; Valek, P.; Weidner, S.; Livadiotis, G. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States); Nicolaou, G., E-mail: helliott@swri.edu [Swedish Institute of Space Physics, Box 812, SE-98128, Kiruna (Sweden)

2016-04-15

The Solar Wind Around Pluto (SWAP) instrument on National Aeronautics and Space Administration's New Horizons Pluto mission has collected solar wind observations en route from Earth to Pluto, and these observations continue beyond Pluto. Few missions have explored the solar wind in the outer heliosphere making this dataset a critical addition to the field. We created a forward model of SWAP count rates, which includes a comprehensive instrument response function based on laboratory and flight calibrations. By fitting the count rates with this model, the proton density (n), speed (V), and temperature (T) parameters are determined. Comparisons between SWAP parameters and both propagated 1 au observations and prior Voyager 2 observations indicate consistency in both the range and mean wind values. These comparisons as well as our additional findings confirm that small and midsized solar wind structures are worn down with increasing distance due to dynamic interaction of parcels of wind with different speed. For instance, the T–V relationship steepens, as the range in V is limited more than the range in T with distance. At times the T–V correlation clearly breaks down beyond 20 au, which may indicate wind currently expanding and cooling may have an elevated T reflecting prior heating and compression in the inner heliosphere. The power of wind parameters at shorter periodicities decreases with distance as the longer periodicities strengthen. The solar rotation periodicity is present in temperature beyond 20 au indicating the observed parcel temperature may reflect not only current heating or cooling, but also heating occurring closer to the Sun.

THE NEW HORIZONS SOLAR WIND AROUND PLUTO (SWAP) OBSERVATIONS OF THE SOLAR WIND FROM 11–33 au

International Nuclear Information System (INIS)

Elliott, H. A.; McComas, D. J.; Valek, P.; Weidner, S.; Livadiotis, G.; Nicolaou, G.

2016-01-01

The Solar Wind Around Pluto (SWAP) instrument on National Aeronautics and Space Administration's New Horizons Pluto mission has collected solar wind observations en route from Earth to Pluto, and these observations continue beyond Pluto. Few missions have explored the solar wind in the outer heliosphere making this dataset a critical addition to the field. We created a forward model of SWAP count rates, which includes a comprehensive instrument response function based on laboratory and flight calibrations. By fitting the count rates with this model, the proton density (n), speed (V), and temperature (T) parameters are determined. Comparisons between SWAP parameters and both propagated 1 au observations and prior Voyager 2 observations indicate consistency in both the range and mean wind values. These comparisons as well as our additional findings confirm that small and midsized solar wind structures are worn down with increasing distance due to dynamic interaction of parcels of wind with different speed. For instance, the T–V relationship steepens, as the range in V is limited more than the range in T with distance. At times the T–V correlation clearly breaks down beyond 20 au, which may indicate wind currently expanding and cooling may have an elevated T reflecting prior heating and compression in the inner heliosphere. The power of wind parameters at shorter periodicities decreases with distance as the longer periodicities strengthen. The solar rotation periodicity is present in temperature beyond 20 au indicating the observed parcel temperature may reflect not only current heating or cooling, but also heating occurring closer to the Sun

ALFVEN WAVE REFLECTION AND TURBULENT HEATING IN THE SOLAR WIND FROM 1 SOLAR RADIUS TO 1 AU: AN ANALYTICAL TREATMENT

International Nuclear Information System (INIS)

Chandran, Benjamin D. G.; Hollweg, Joseph V.

2009-01-01

We study the propagation, reflection, and turbulent dissipation of Alfven waves in coronal holes and the solar wind. We start with the Heinemann-Olbert equations, which describe non-compressive magnetohydrodynamic fluctuations in an inhomogeneous medium with a background flow parallel to the background magnetic field. Following the approach of Dmitruk et al., we model the nonlinear terms in these equations using a simple phenomenology for the cascade and dissipation of wave energy and assume that there is much more energy in waves propagating away from the Sun than waves propagating toward the Sun. We then solve the equations analytically for waves with periods of hours and longer to obtain expressions for the wave amplitudes and turbulent heating rate as a function of heliocentric distance. We also develop a second approximate model that includes waves with periods of roughly one minute to one hour, which undergo less reflection than the longer-period waves, and compare our models to observations. Our models generalize the phenomenological model of Dmitruk et al. by accounting for the solar wind velocity, so that the turbulent heating rate can be evaluated from the coronal base out past the Alfven critical point-that is, throughout the region in which most of the heating and acceleration occurs. The simple analytical expressions that we obtain can be used to incorporate Alfven-wave reflection and turbulent heating into fluid models of the solar wind.

Astrospheres and Solar-like Stellar Winds

Directory of Open Access Journals (Sweden)

Wood Brian E.

2004-07-01

Full Text Available Stellar analogs for the solar wind have proven to be frustratingly difficult to detect directly. However, these stellar winds can be studied indirectly by observing the interaction regions carved out by the collisions between these winds and the interstellar medium (ISM. These interaction regions are called "astrospheres", analogous to the "heliosphere" surrounding the Sun. The heliosphere and astrospheres contain a population of hydrogen heated by charge exchange processes that can produce enough H I Ly alpha absorption to be detectable in UV spectra of nearby stars from the Hubble Space Telescope (HST. The amount of astrospheric absorption is a diagnostic for the strength of the stellar wind, so these observations have provided the first measurements of solar-like stellar winds. Results from these stellar wind studies and their implications for our understanding of the solar wind are reviewed here. Of particular interest are results concerning the past history of the solar wind and its impact on planetary atmospheres.

Heat flux dropouts in the solar wind and Coulomb scattering effects

International Nuclear Information System (INIS)

Fitzenreiter, R.J.; Ogilvie, K.W.

1992-01-01

Measurements of solar wind electrons at ISEE 3 located 0.01 AU upstream from the Earth indicate periods of time when the flux of antisunward suprathermal electrons decreases suddenly, leaving the velocity distribution nearly isotropic and causing the solar wind heat flux to drop. These heat flux dropouts (HFDs) are usually found in regions of increased plasma density and decreased electron temperature, and they are associated with sector boundaries. It has been suggested that HFDs may be due either to disconnection from the Sun of the magnetic flux tube in which they are found, or to enhanced Coulomb scattering of halo electrons in transit from the Sun to the Earth. Using the vector electron spectrometer on ISEE 1, the authors have found eight intervals of greatly reduced heat flux which appear to be associated with HFDs at ISEE 3. Five of the eight events were delayed by an appropriate convection time and had approximately the same duration as the corresponding ISEE 3 event. Velocity distributions during HFDs at ISEE 1 show that the depletion of halo electrons traveling away from the Sun is most pronounced in the 100-eV range, while there is essentially no depletion in the 1-keV range, and that in four cases the magnitude of the halo depletion and its upper velocity limit both depend on the density increase in the HFD. These results are shown to be in agreement with the υ -3 dependence of the Coulomb collision frequency. Thus the authors conclude that Coulomb scattering effects play a substantial role in at least some heat flux dropout events

CORONAL HEATING BY SURFACE ALFVEN WAVE DAMPING: IMPLEMENTATION IN A GLOBAL MAGNETOHYDRODYNAMICS MODEL OF THE SOLAR WIND

Energy Technology Data Exchange (ETDEWEB)

Evans, R. M. [NASA Goddard Space Flight Center, Space Weather Lab, Greenbelt, MD 20771 (United States); Opher, M. [Astronomy Department, Boston University, 675 Commonwealth Avenue, Boston, MA 02215 (United States); Oran, R.; Van der Holst, B.; Sokolov, I. V.; Frazin, R.; Gombosi, T. I. [Center for Space Environment Modeling, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States); Vasquez, A., E-mail: Rebekah.e.frolov@nasa.gov [Instituto de Astronomia y Fisica del Espacio (CONICET-UBA) and FCEN (UBA), CC 67, Suc 28, Ciudad de Buenos Aires (Argentina)

2012-09-10

The heating and acceleration of the solar wind is an active area of research. Alfven waves, because of their ability to accelerate and heat the plasma, are a likely candidate in both processes. Many models have explored wave dissipation mechanisms which act either in closed or open magnetic field regions. In this work, we emphasize the boundary between these regions, drawing on observations which indicate unique heating is present there. We utilize a new solar corona component of the Space Weather Modeling Framework, in which Alfven wave energy transport is self-consistently coupled to the magnetohydrodynamic equations. In this solar wind model, the wave pressure gradient accelerates and wave dissipation heats the plasma. Kolmogorov-like wave dissipation as expressed by Hollweg along open magnetic field lines was presented in van der Holst et al. Here, we introduce an additional dissipation mechanism: surface Alfven wave (SAW) damping, which occurs in regions with transverse (with respect to the magnetic field) gradients in the local Alfven speed. For solar minimum conditions, we find that SAW dissipation is weak in the polar regions (where Hollweg dissipation is strong), and strong in subpolar latitudes and the boundaries of open and closed magnetic fields (where Hollweg dissipation is weak). We show that SAW damping reproduces regions of enhanced temperature at the boundaries of open and closed magnetic fields seen in tomographic reconstructions in the low corona. Also, we argue that Ulysses data in the heliosphere show enhanced temperatures at the boundaries of fast and slow solar wind, which is reproduced by SAW dissipation. Therefore, the model's temperature distribution shows best agreement with these observations when both dissipation mechanisms are considered. Lastly, we use observational constraints of shock formation in the low corona to assess the Alfven speed profile in the model. We find that, compared to a polytropic solar wind model, the wave

TIME-DEPENDENT TURBULENT HEATING OF OPEN FLUX TUBES IN THE CHROMOSPHERE, CORONA, AND SOLAR WIND

Energy Technology Data Exchange (ETDEWEB)

Woolsey, L. N.; Cranmer, S. R., E-mail: lwoolsey@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

2015-10-01

We investigate several key questions of plasma heating in open-field regions of the corona that connect to the solar wind. We present results for a model of Alfvén-wave-driven turbulence for three typical open magnetic field structures: a polar coronal hole, an open flux tube neighboring an equatorial streamer, and an open flux tube near a strong-field active region. We compare time-steady, one-dimensional turbulent heating models against fully time-dependent three-dimensional reduced-magnetohydrodynamic modeling of BRAID. We find that the time-steady results agree well with time-averaged results from BRAID. The time dependence allows us to investigate the variability of the magnetic fluctuations and of the heating in the corona. The high-frequency tail of the power spectrum of fluctuations forms a power law whose exponent varies with height, and we discuss the possible physical explanation for this behavior. The variability in the heating rate is bursty and nanoflare-like in nature, and we analyze the amount of energy lost via dissipative heating in transient events throughout the simulation. The average energy in these events is 10{sup 21.91} erg, within the “picoflare” range, and many events reach classical “nanoflare” energies. We also estimated the multithermal distribution of temperatures that would result from the heating-rate variability, and found good agreement with observed widths of coronal differential emission measure distributions. The results of the modeling presented in this paper provide compelling evidence that turbulent heating in the solar atmosphere by Alfvén waves accelerates the solar wind in open flux tubes.

Intermittent heating of the corona as an alternative to generate fast solar wind flows

International Nuclear Information System (INIS)

Grappin, R.; Mangeney, A.; Schwartz, S.J.; Feldman, W.C.

1999-01-01

We discuss a new alternative to the generation of fast streams which does not require momentum addition beyond the critical point. We consider the consequences on the solar wind of temporally intermittent heat depositions at the base of the wind. With the help of 1d hydrodynamic simulations we show that the instantaneous wind velocity profile fluctuates around an average profile well above the one corresponding to the Parker solution with a coronal temperature equal to the average coronal temperature imposed at the bottom of the numerical domain. The origin of this result lies in a previously overlooked phenomenon, the overexpansion of hot plasma regions in the subsonic wind. copyright 1999 American Institute of Physics

Solar wind acceleration in coronal holes

International Nuclear Information System (INIS)

Kopp, R.A.

1978-01-01

Past attempts to explain the large solar wind velocities in high speed streams by theoretical models of the expansion have invoked either extended nonthermal heating of the corona, heat flux inhibition, or direct addition of momentum to the expanding coronal plasma. Several workers have shown that inhibiting the heat flux at low coronal densities is probably not adequate to explain quantitatively the observed plasma velocities in high speed streams. It stressed that, in order to account for both these large plasma velocities and the low densities found in coronal holes (from which most high speed streams are believed to emanate), extended heating by itself will not suffice. One needs a nonthermal mechanism to provide the bulk acceleration of the high wind plasma close to the sun, and the most likely candidate at present is direct addition of the momentum carried by outward-propagating waves to the expanding corona. Some form of momentum addition appears to be absolutely necessary if one hopes to build quantitatively self-consistent models of coronal holes and high speed solar wind streams

Three-fluid, three-dimensional magnetohydrodynamic solar wind model with eddy viscosity and turbulent resistivity

Energy Technology Data Exchange (ETDEWEB)

Usmanov, Arcadi V.; Matthaeus, William H. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Goldstein, Melvyn L., E-mail: arcadi.usmanov@nasa.gov [Code 672, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2014-06-10

We have developed a three-fluid, three-dimensional magnetohydrodynamic solar wind model that incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating. The solar wind plasma is described as a system of co-moving solar wind protons, electrons, and interstellar pickup protons, with separate energy equations for each species. Numerical steady-state solutions of Reynolds-averaged solar wind equations coupled with turbulence transport equations for turbulence energy, cross helicity, and correlation length are obtained by the time relaxation method in the corotating with the Sun frame of reference in the region from 0.3 to 100 AU (but still inside the termination shock). The model equations include the effects of electron heat conduction, Coulomb collisions, photoionization of interstellar hydrogen atoms and their charge exchange with the solar wind protons, turbulence energy generation by pickup protons, and turbulent heating of solar wind protons and electrons. The turbulence transport model is based on the Reynolds decomposition and turbulence phenomenologies that describe the conversion of fluctuation energy into heat due to a turbulent cascade. In addition to using separate energy equations for the solar wind protons and electrons, a significant improvement over our previous work is that the turbulence model now uses an eddy viscosity approximation for the Reynolds stress tensor and the mean turbulent electric field. The approximation allows the turbulence model to account for driving of turbulence by large-scale velocity gradients. Using either a dipole approximation for the solar magnetic field or synoptic solar magnetograms from the Wilcox Solar Observatory for assigning boundary conditions at the coronal base, we apply the model to study the global structure of the solar wind and its three-dimensional properties, including embedded turbulence, heating, and acceleration throughout the heliosphere. The model results are

Solar-wind predictions for the Parker Solar Probe orbit. Near-Sun extrapolations derived from an empirical solar-wind model based on Helios and OMNI observations

Science.gov (United States)

Venzmer, M. S.; Bothmer, V.

2018-03-01

Context. The Parker Solar Probe (PSP; formerly Solar Probe Plus) mission will be humanitys first in situ exploration of the solar corona with closest perihelia at 9.86 solar radii (R⊙) distance to the Sun. It will help answer hitherto unresolved questions on the heating of the solar corona and the source and acceleration of the solar wind and solar energetic particles. The scope of this study is to model the solar-wind environment for PSPs unprecedented distances in its prime mission phase during the years 2018 to 2025. The study is performed within the Coronagraphic German And US SolarProbePlus Survey (CGAUSS) which is the German contribution to the PSP mission as part of the Wide-field Imager for Solar PRobe. Aim. We present an empirical solar-wind model for the inner heliosphere which is derived from OMNI and Helios data. The German-US space probes Helios 1 and Helios 2 flew in the 1970s and observed solar wind in the ecliptic within heliocentric distances of 0.29 au to 0.98 au. The OMNI database consists of multi-spacecraft intercalibrated in situ data obtained near 1 au over more than five solar cycles. The international sunspot number (SSN) and its predictions are used to derive dependencies of the major solar-wind parameters on solar activity and to forecast their properties for the PSP mission. Methods: The frequency distributions for the solar-wind key parameters, magnetic field strength, proton velocity, density, and temperature, are represented by lognormal functions. In addition, we consider the velocity distributions bi-componental shape, consisting of a slower and a faster part. Functional relations to solar activity are compiled with use of the OMNI data by correlating and fitting the frequency distributions with the SSN. Further, based on the combined data set from both Helios probes, the parameters frequency distributions are fitted with respect to solar distance to obtain power law dependencies. Thus an empirical solar-wind model for the inner

Alfvén wave heating of heavy ions in the expanding solar wind: Hybrid simulations

Czech Academy of Sciences Publication Activity Database

Hellinger, Petr; Velli, M.; Trávníček, Pavel; Gary, S. P.; Goldstein, B. E.; Liewer, P. C.

2005-01-01

Roč. 110, - (2005), A12109/1-A12109/11 ISSN 0148-0227 R&D Projects: GA AV ČR IAA3042403 Institutional research plan: CEZ:AV0Z30420517 Keywords : Alfvén waves * solar wind heating * microinstabilities Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.784, year: 2005

Transition region, coronal heating and the fast solar wind

Science.gov (United States)

Li, Xing

2003-07-01

It is assumed that magnetic flux tubes are strongly concentrated at the boundaries of supergranule convection cells. A power law spectrum of high frequency Alfvén waves with a spectral index -1 originating from the sun is assumed to supply all the energy needed to energize the plasma flowing in such magnetic flux tubes. At the high frequency end, the waves are eroded by ions due to ion cyclotron resonance. The magnetic flux concentration is essential since it allows a sufficiently strong energy flux to be carried by high frequency ion cyclotron waves and these waves can be readily released at the coronal base by cyclotron resonance. The main results are: 1. The waves are capable of creating a steep transition region, a hot corona and a fast solar wind if both the wave frequency is high enough and the magnetic flux concentration is sufficiently strong in the boundaries of the supergranule convection zone. 2. By primarily heating alpha particles only, it is possible to produce a steep transition region, a hot corona and a fast solar wind. Coulomb coupling plays a key role in transferring the thermal energy of alpha particles to protons and electrons at the corona base. The electron thermal conduction then does the remaining job to create a sharp transition region. 3. Plasma species (even ions) may already partially lose thermal equilibrium in the transition region, and minor ions may already be faster than protons at the very base of the corona. 4. The model predicts high temperature alpha particles (Talpha ~ 2 x 107 K) and low proton temperatures (Tp solar radii, suggesting that hydrogen Lyman lines observed by UVCS above coronal holes may be primarily broadened by Alfvén waves in this range.

Effect of Alfvenic fluctuations on the solar wind

International Nuclear Information System (INIS)

Chien, T.H.

1974-01-01

The major source of microscale fluctuations in the interplanetary medium due to the outwardly propagating Alfven waves is considered. The effect of the Alfven waves on the supersonic expansion of the solar wind is studied under the assumption that the motion of the interplanetary medium can be resolved physically into a comparatively smooth and slowly varying mesoscale flow and field with very irregular disordered incompressible microscale Alfvenic fluctuations superposed on it. The important features of the solar wind such as heat conduction flux, spiral interplanetary magnetic field, and proton thermal anisotropy are included in the theory. For inviscid, steady state, spherically symmetrical model of the solar wind, the two-fluid formulation of the background mesoscale MHD equations is obtained. The results show that during the expansion process, fluctuation energy is converted into the kinetic energy of the solar wind. Due to the presence of the Alfvenic fluctuations, the velocity of the solar wind is about 5 percent higher than that without considering the fluctuations. (U.S.)

Simulation study of solar wind push on a charged wire: basis of solar wind electric sail propulsion

Directory of Open Access Journals (Sweden)

P. Janhunen

2007-03-01

Full Text Available One possibility for propellantless propulsion in space is to use the momentum flux of the solar wind. A way to set up a solar wind sail is to have a set of thin long wires which are kept at high positive potential by an onboard electron gun so that the wires repel and deflect incident solar wind protons. The efficiency of this so-called electric sail depends on how large force a given solar wind exerts on a wire segment and how large electron current the wire segment draws from the solar wind plasma when kept at a given potential. We use 1-D and 2-D electrostatic plasma simulations to calculate the force and present a semitheoretical formula which captures the simulation results. We find that under average solar wind conditions at 1 AU the force per unit length is (5±1×10−8 N/m for 15 kV potential and that the electron current is accurately given by the well-known orbital motion limited (OML theory cylindrical Langmuir probe formula. Although the force may appear small, an analysis shows that because of the very low weight of a thin wire per unit length, quite high final speeds (over 50 km/s could be achieved by an electric sailing spacecraft using today's flight-proved components. It is possible that artificial electron heating of the plasma in the interaction region could increase the propulsive effect even further.

Turbulent Transport in a Three-dimensional Solar Wind

Energy Technology Data Exchange (ETDEWEB)

Shiota, D. [Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Aichi 464-8601 (Japan); Zank, G. P.; Adhikari, L.; Hunana, P. [Center for Space Plasma and Aeronomic Research (CSPAR), Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Telloni, D. [INAF—Astrophysical Observatory of Torino, Via Osservatorio 20, I-10025 Pino Torinese (Italy); Bruno, R., E-mail: shiota@isee.nagoya-u.ac.jp [INAF-IAPS Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy)

2017-03-01

Turbulence in the solar wind can play essential roles in the heating of coronal and solar wind plasma and the acceleration of the solar wind and energetic particles. Turbulence sources are not well understood and thought to be partly enhanced by interaction with the large-scale inhomogeneity of the solar wind and the interplanetary magnetic field and/or transported from the solar corona. To investigate the interaction with background inhomogeneity and the turbulence sources, we have developed a new 3D MHD model that includes the transport and dissipation of turbulence using the theoretical model of Zank et al. We solve for the temporal and spatial evolution of three moments or variables, the energy in the forward and backward fluctuating modes and the residual energy and their three corresponding correlation lengths. The transport model is coupled to our 3D model of the inhomogeneous solar wind. We present results of the coupled solar wind-turbulence model assuming a simple tilted dipole magnetic configuration that mimics solar minimum conditions, together with several comparative intermediate cases. By considering eight possible solar wind and turbulence source configurations, we show that the large-scale solar wind and IMF inhomogeneity and the strength of the turbulence sources significantly affect the distribution of turbulence in the heliosphere within 6 au. We compare the predicted turbulence distribution results from a complete solar minimum model with in situ measurements made by the Helios and Ulysses spacecraft, finding that the synthetic profiles of the turbulence intensities show reasonable agreement with observations.

Ion acoustic waves in the solar wind

International Nuclear Information System (INIS)

Gurnett, D.A.; Frank, L.A.

1978-01-01

Plasma wave measurements on the Helios I and 2 spacecraft have revealed the occurrence of electric field turbulence in the solar wind at frequencies between the electron and ion plasma frequencies. Wavelength measurements with the Imp 6 spacecraft now provide strong evidence that these waves are short-wavelength ion acoustic waves which are Doppler-shifted upward in frequency by the motion of the solar wind. Comparison of the Helios results with measurements from the earth-orbiting Imp 6 and 8 spacecraft shows that the ion acoustic turbulence detected in interplanetary space has characteristics essentially identical to those of bursts of electrostatic turbulence generated by protons streaming into the solar wind from the earth's bow shock. In a few cases, enhanced ion acoustic wave intensities have been observed in direct association with abrupt increases in the anisotropy of the solar wind electron distribution. This relationship strongly suggests that the ion acoustic waves detected by Helios far from the earth are produced by an electron heat flux instability, as was suggested by Forslund. Possible related mechanisms which could explain the generation of ion acoustic waves by protons streaming into the solar wind from the earth's bow shock are also considered

RECONSTRUCTING THE SOLAR WIND FROM ITS EARLY HISTORY TO CURRENT EPOCH

Energy Technology Data Exchange (ETDEWEB)

Airapetian, Vladimir S.; Usmanov, Arcadi V., E-mail: vladimir.airapetian@nasa.gov, E-mail: avusmanov@gmail.com [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

2016-02-01

Stellar winds from active solar-type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass-loss rates cannot be directly derived from observations. We employed a three-dimensional magnetohydrodynamic Alfvén wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass-loss rate, terminal velocity, and wind temperature at 0.7, 2, and 4.65 Gyr. Our model treats the wind thermal electrons, protons, and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electron temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfvén wave amplitude, and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constrains. Our model results show that the velocity of the paleo solar wind was twice as fast, ∼50 times denser and 2 times hotter at 1 AU in the Sun's early history at 0.7 Gyr. The theoretical calculations of mass-loss rate appear to be in agreement with the empirically derived values for stars of various ages. These results can provide realistic constraints for wind dynamic pressures on magnetospheres of (exo)planets around the young Sun and other active stars, which is crucial in realistic assessment of the Joule heating of their ionospheres and corresponding effects of atmospheric erosion.

RECONSTRUCTING THE SOLAR WIND FROM ITS EARLY HISTORY TO CURRENT EPOCH

International Nuclear Information System (INIS)

Airapetian, Vladimir S.; Usmanov, Arcadi V.

2016-01-01

Stellar winds from active solar-type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass-loss rates cannot be directly derived from observations. We employed a three-dimensional magnetohydrodynamic Alfvén wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass-loss rate, terminal velocity, and wind temperature at 0.7, 2, and 4.65 Gyr. Our model treats the wind thermal electrons, protons, and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electron temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfvén wave amplitude, and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constrains. Our model results show that the velocity of the paleo solar wind was twice as fast, ∼50 times denser and 2 times hotter at 1 AU in the Sun's early history at 0.7 Gyr. The theoretical calculations of mass-loss rate appear to be in agreement with the empirically derived values for stars of various ages. These results can provide realistic constraints for wind dynamic pressures on magnetospheres of (exo)planets around the young Sun and other active stars, which is crucial in realistic assessment of the Joule heating of their ionospheres and corresponding effects of atmospheric erosion

Solar-wind minor ions: recent observations

International Nuclear Information System (INIS)

Bame, S.J.

1982-01-01

During the years following the Solar Wind Four Conference at Burghausen our knowledge of the solar wind ion composition and dynamics has grown. There have been some surprises, and our understanding of the evolution of the solar wind has been improved. Systematic studies have shown that the minor ions generally travel with a common bulk speed and have temperatures roughly proportional to their masses. It has been determined that the 3 He ++ content varies greatly; 3 He ++ / 4 He ++ ranges from as high as 10 2 values to below 2 x 10 - 4 . In some solar wind flows which can be related to energetic coronal events, the minor ions are found in unusual ionization states containing Fe 16 + as a prominent ion, showing that the states were formed at unusually high temperatures. Unexpectedly, in a few flows substantial quantities of 4 He + have been detected, sometimes with ions identifiable as O 2 + and O 3 + . Surprisingly, in some of these examples the ionization state is mixed showing that part of the plasma escaped the corona without attaining the usual million-degree temperatures while other parts were heated more nearly in the normal manner. Additionally, detailed studies of the minor ions have increased our understanding of the coronal expansion. For example, such studies have contributed to identifying near equatorial coronal streamers as the source of solar wind flows between high speed streams

ANALYSIS OF MEASURED AND MODELED SOLAR RADIATION AT THE TARS SOLAR HEATING PLANT IN DENMARK

DEFF Research Database (Denmark)

Tian, Zhiyong; Perers, Bengt; Furbo, Simon

2017-01-01

, such as solar radiation, inlet and outlet temperature for the solar collector field, flow rate and pressure, ambient temperature, Wind speed and wind direction were measured. Global horizontal radiation, direct normal irradiation (DNI) and total radiation on the tilted collector plane of the flat plate...... collector field have been measured in Tars solar heating plant. To determine the accuracy of modeled and measured solar radiation in Tars solar heating plant, monthly comparisons of measured and calculated radiation using 6 empirical models have been carried out. Comparisons of measured and modeled total......A novel combined solar heating plant with tracking parabolic trough collectors (PTC) and flat plate collectors (FPC) has been constructed and put into operation in Tars, 30 km north of Aalborg, Denmark in August 2015. To assess the operation performance of the plant, detailed parameters...

DISSIPATION OF PARALLEL AND OBLIQUE ALFVÉN-CYCLOTRON WAVES—IMPLICATIONS FOR HEATING OF ALPHA PARTICLES IN THE SOLAR WIND

Energy Technology Data Exchange (ETDEWEB)

Maneva, Y. G.; Poedts, Stefaan [Centre for Mathematical Plasma Astrophysics, KU Leuven, B-3001 Leuven (Belgium); Viñas, Adolfo F.; Moya, Pablo S.; Wicks, Robert T., E-mail: yana.maneva@wis.kuleuven.be [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2015-11-20

We perform 2.5D hybrid simulations with massless fluid electrons and kinetic particle-in-cell ions to study the temporal evolution of ion temperatures, temperature anisotropies, and velocity distribution functions in relation to the dissipation and turbulent evolution of a broadband spectrum of parallel and obliquely propagating Alfvén-cyclotron waves. The purpose of this paper is to study the relative role of parallel versus oblique Alfvén-cyclotron waves in the observed heating and acceleration of alpha particles in the fast solar wind. We consider collisionless homogeneous multi-species plasma, consisting of isothermal electrons, isotropic protons, and a minor component of drifting α particles in a finite-β fast stream near the Earth. The kinetic ions are modeled by initially isotropic Maxwellian velocity distribution functions, which develop nonthermal features and temperature anisotropies when a broadband spectrum of low-frequency nonresonant, ω ≤ 0.34 Ω{sub p}, Alfvén-cyclotron waves is imposed at the beginning of the simulations. The initial plasma parameter values, such as ion density, temperatures, and relative drift speeds, are supplied by fast solar wind observations made by the Wind spacecraft at 1 AU. The imposed broadband wave spectra are left-hand polarized and resemble Wind measurements of Alfvénic turbulence in the solar wind. The imposed magnetic field fluctuations for all cases are within the inertial range of the solar wind turbulence and have a Kraichnan-type spectral slope α = −3/2. We vary the propagation angle from θ = 0° to θ = 30° and θ = 60°, and find that the heating of alpha particles is most efficient for the highly oblique waves propagating at 60°, whereas the protons exhibit perpendicular cooling at all propagation angles.

DISSIPATION OF PARALLEL AND OBLIQUE ALFVÉN-CYCLOTRON WAVES—IMPLICATIONS FOR HEATING OF ALPHA PARTICLES IN THE SOLAR WIND

International Nuclear Information System (INIS)

Maneva, Y. G.; Poedts, Stefaan; Viñas, Adolfo F.; Moya, Pablo S.; Wicks, Robert T.

2015-01-01

We perform 2.5D hybrid simulations with massless fluid electrons and kinetic particle-in-cell ions to study the temporal evolution of ion temperatures, temperature anisotropies, and velocity distribution functions in relation to the dissipation and turbulent evolution of a broadband spectrum of parallel and obliquely propagating Alfvén-cyclotron waves. The purpose of this paper is to study the relative role of parallel versus oblique Alfvén-cyclotron waves in the observed heating and acceleration of alpha particles in the fast solar wind. We consider collisionless homogeneous multi-species plasma, consisting of isothermal electrons, isotropic protons, and a minor component of drifting α particles in a finite-β fast stream near the Earth. The kinetic ions are modeled by initially isotropic Maxwellian velocity distribution functions, which develop nonthermal features and temperature anisotropies when a broadband spectrum of low-frequency nonresonant, ω ≤ 0.34 Ω p , Alfvén-cyclotron waves is imposed at the beginning of the simulations. The initial plasma parameter values, such as ion density, temperatures, and relative drift speeds, are supplied by fast solar wind observations made by the Wind spacecraft at 1 AU. The imposed broadband wave spectra are left-hand polarized and resemble Wind measurements of Alfvénic turbulence in the solar wind. The imposed magnetic field fluctuations for all cases are within the inertial range of the solar wind turbulence and have a Kraichnan-type spectral slope α = −3/2. We vary the propagation angle from θ = 0° to θ = 30° and θ = 60°, and find that the heating of alpha particles is most efficient for the highly oblique waves propagating at 60°, whereas the protons exhibit perpendicular cooling at all propagation angles

Simulation study of solar wind push on a charged wire: basis of solar wind electric sail propulsion

Directory of Open Access Journals (Sweden)

P. Janhunen

2007-03-01

Full Text Available One possibility for propellantless propulsion in space is to use the momentum flux of the solar wind. A way to set up a solar wind sail is to have a set of thin long wires which are kept at high positive potential by an onboard electron gun so that the wires repel and deflect incident solar wind protons. The efficiency of this so-called electric sail depends on how large force a given solar wind exerts on a wire segment and how large electron current the wire segment draws from the solar wind plasma when kept at a given potential. We use 1-D and 2-D electrostatic plasma simulations to calculate the force and present a semitheoretical formula which captures the simulation results. We find that under average solar wind conditions at 1 AU the force per unit length is (5±1×10⁻⁸ N/m for 15 kV potential and that the electron current is accurately given by the well-known orbital motion limited (OML theory cylindrical Langmuir probe formula. Although the force may appear small, an analysis shows that because of the very low weight of a thin wire per unit length, quite high final speeds (over 50 km/s could be achieved by an electric sailing spacecraft using today's flight-proved components. It is possible that artificial electron heating of the plasma in the interaction region could increase the propulsive effect even further.

Colliding winds: Interaction regions with strong heat conduction

International Nuclear Information System (INIS)

Imamura, J.N.; Chevalier, R.A.

1984-01-01

The interaction of fast stellar wind with a slower wind from previous mass loss gives rise to a region of hot, shocked gas. We obtain self-similar solutions for the interaction region under the assumptions of constant mass loss rate and wind velocity for the two winds, conversion of energy in the shock region, and either isothermal electrons and adiabatic ions or isothermal electrons ad ions in the shocked region. The isothermal assumption is intended to show the effects of strog heat conduction. The solutions have no heat conduction through the shock waves and assume that the electron and ion temperatures are equilibriated in the shock waves. The one-temperature isothermal solutions have nearly constant density through the shocked region, while the two-temperature solutions are intermediate between the one-temperature adiabatic and isothermal solutions. In the two-temperature solutions, the ion temperature goes to zero at the point where the gas comoves with the shocked region and the density peaks at this point. The solution may qualitatively describe the effects of heat conduction on interaction regions in the solar wind. It will be important to determine whether the assumption of no thermal waves outside the shocked region applies to shock waves in the solar wind

The 1991 Japan Solar Energy Society. Japan Wind Energy Association Joint Conference

Science.gov (United States)

1991-09-01

Thie paper summarizes the lectures presented at the research presentation conference held by the Japan Solar Energy Society and the Japan Wind Energy Association. The contents include a lecture relating to photovoltaic cells intended for efficiency improvement; a lecture relating to a light power generation system including the field test reports, improvements on peripheral devices and output characteristics; a lecture relating to optical chemistry; a lecture relating to heat pumps utilizing solar heat and well water; a lecture relating air conditioning utilizing photovoltaic cells; a lecture relating to heat systems utilizing solar heat directly; a lecture relating to heat collection; a lecture relating to cold heat for cooling using earth tubes; a lecture relating to direct utilization of ground water heat and solar heat; a lecture relating to underground heat storage; a lecture relating to accumulation of cold heat and hot heat; a lecture relating to insolation on the amount of insolation and spectroscopy; a lecture relating to light collection intended of energy saving; a lecture relating to improving materials including light collecting plates and thin films; a lecture relating to development and characteristics of solar cars; and a lecture relating to wind energy.

Understanding non-equilibrium collisional and expansion effects in the solar wind with Parker Solar Probe

Science.gov (United States)

Korreck, K. E.; Klein, K. G.; Maruca, B.; Alterman, B. L.

2017-12-01

The evolution of the solar wind from the corona to the Earth and throughout the heliosphere is a complex interplay between local micro kinetics and large scale expansion effects. These processes in the solar wind need to be separated in order to understand and distinguish the dominant mechanism for heating and acceleration of the solar wind. With the upcoming launch in 2018 of Parker Solar Probe and the launch of Solar Orbiter after, addressing the local and global phenomena will be enabled with in situ measurements. Parker Solar Probe will go closer to the Sun than any previous mission enabling the ability to examine the solar wind at an early expansion age. This work examines the predictions for what will be seen inside of the 0.25 AU (54 solar radii) where Parker Solar Probe will take measurements and lays the groundwork for disentangling the expansion and collisional effects. In addition, methods of thermal plasma data analysis to determine the stability of the plasma in the Parker Solar Probe measurements will be discussed.

Solar wind modulation of the Martian ionosphere observed by Mars Global Surveyor

Directory of Open Access Journals (Sweden)

J.-S. Wang

2004-06-01

Full Text Available Electron density profiles in the Martian ionosphere observed by the radio occultation experiment on board Mars Global Surveyor have been analyzed to determine if the densities are influenced by the solar wind. Evidence is presented that the altitude of the maximum ionospheric electron density shows a positive correlation to the energetic proton flux in the solar wind. The solar wind modulation of the Martian ionosphere can be attributed to heating of the neutral atmosphere by the solar wind energetic proton precipitation. The modulation is observed to be most prominent at high solar zenith angles. It is argued that this is consistent with the proposed modulation mechanism.

Magnetic pumping as a source of particle heating in the solar wind

Science.gov (United States)

Lichko, E. R.; Egedal, J.; Daughton, W. S.; Kasper, J. C.

2017-12-01

Magnetic pumping is a means of heating plasmas for both fusion and astrophysical applications. In this study a magnetic pumping model is developed as a possible explanation for the heating and the generation of power-law distribution functions observed in the solar wind plasma. In most previous studies turbulent energy is only dissipated at microscopic kinetic scales. In contrast, magnetic pumping energizes the particles through the largest scale turbulent fluctuations, thus bypassing the energy cascade. Kinetic simulations are applied to verify these analytic predictions. Previous results for the one-dimensional model, as well as initial results for a two-dimensional model which includes the effects of trapped and passing particles are presented. Preliminary results of the presence of this mechanism in the bow shock region, using spacecraft data from the Magnetospheric Multiscale mission, are presented as well.

Verification of high-speed solar wind stream forecasts using operational solar wind models

DEFF Research Database (Denmark)

Reiss, Martin A.; Temmer, Manuela; Veronig, Astrid M.

2016-01-01

and the background solar wind conditions. We found that both solar wind models are capable of predicting the large-scale features of the observed solar wind speed (root-mean-square error, RMSE ≈100 km/s) but tend to either overestimate (ESWF) or underestimate (WSA) the number of high-speed solar wind streams (threat......High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate...... high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the Advanced Composition Explorer (ACE) spacecraft for the years 2011 to 2014. While the ESWF makes use of an empirical relation...

Voyager observations of solar wind proton temperature - 1-10 AU

Science.gov (United States)

Gazis, P. R.; Lazarus, A. J.

1982-01-01

Simultaneous measurements are made of the solar wind proton temperatures by the Voyager 1 and 2 spacecraft, far from earth, and the IMP 8 spacecraft in earth orbit. This technique permits a separation of radial and temporal variations of solar wind parameters. The average value of the proton temperature between 1 and 9 AU is observed to decrease as r (the heliocentric radius) to the -(0.7 + or - 0.2). This is slower than would be expected for adiabatic expansion. A detailed examination of the solar wind stream structure shows that considerable heating occurs at the interface between high and low speed streams.

Heliospheric pick-up ions influencing thermodynamics and dynamics of the distant solar wind

Directory of Open Access Journals (Sweden)

H. J. Fahr

2002-01-01

Full Text Available Neutral interstellar H-atoms penetrate into the inner heliosphere and upon the event of ionization are converted into pick-up ions (PUIs. The magnetized solar wind flow incorporates these ions into the plasma bulk and enforces their co-motion. By nonlinear interactions with wind-entrained Alfvén waves, these ions are then processed in the comoving velocity space. The complete pick-up process is connected with forces acting back to the original solar wind ion flow, thereby decelerating and heating the solar wind plasma. As we show here, the resulting deceleration cannot be treated as a pure loading effect, but requires adequate consideration of the action of the pressure of PUI-scattered waves operating by the PUI pressure gradient. Hereby, it is important to take into proper account the stochastic acceleration which PUIs suffer from at their convection out of the inner heliosphere by quasi-linear interactions with MHD turbulences. Only then can the presently reported VOYAGER observations of solar wind decelerations and heatings in the outer heliosphere be understood in view of the most likely values of interstellar gas parameters, such as an H-atom density of 0.12 cm-3 . Solar wind protons (SWPs appear to be globally heated in their motion to larger solar distances. Ascribing the needed heat transfer to the action of suprathermal PUIs, which drive MHD waves that are partly absorbed by SWPs, in order to establish the observed SWP polytropy, we can obtain a quantitative expression for the solar wind proton pressure as a function of solar distance. This expression clearly shows the change from an adiabatic to a quasi-polytropic SWP behaviour with a decreasing polytropic index at increasing distances. This also allows one to calculate the average percentage of initial pick-up energy fed into the thermal proton energy. In a first order evaluation of this expression, we can estimate that about 10% of the initial PUI injection energy is eventually

Analysis of Ion Charge States in Solar Wind and CMEs Arati ...

Indian Academy of Sciences (India)

states of various elements observed in situ in the solar wind and CMEs. The competing processes of ionization and recombination lead to depar- tures from collision ionization equilibrium. The use of this as a diagnostic of acceleration and heating processes of the solar wind and CMEs is sensi- tive to the accuracy of the ...

A Wind Tunnel Investigation of the Influence of Solar-Induced Wall-Heating on the Flow Regime within a Simulated Urban Street Canyon

International Nuclear Information System (INIS)

Kovar-Panskus, A.; Moulinneuf, L.; Savory, E.; Abdelqari, A.; Sini, J.-F.; Rosant, J.-M.; Robins, A.; Toy, N.

2002-01-01

A wind tunnel study has been undertaken to assess the influence of solar-induced wall heating on the airflow pattern within a street canyon under low-speed wind conditions. This flow is normally dominated by large-scale vortical motion, such that the wind moves downwards at the downstream wall. In the present work the aim has been to examine whether the buoyancy forces generated at this wall by solar-induced heating are of sufficient strength to oppose the downward inertial forces and, thereby, change the canyon flow pattern. Such changes will also influence the dispersion of pollutants within the street. In the experiments the windward-facing wall of a canyon has been uniformly heated to simulate the effect of solar radiation.Four different test cases, representing different degrees of buoyancy (defined by a test Froude number, Fr), have been examined using a simple, 2-D, square-section canyon model in a wind tunnel. For reference purposes, the neutral case (no wall heating), has also been studied. The approach flow boundary layer conditions have been well defined, with the wind normal to the main canyon axis, and measurements have been taken of canyon wall and air temperatures and profiles of mean velocities and turbulence intensities.Analysis of the results shows clear differences in the flow patterns. As Fr decreases from the neutral case there are reductions of up to 50% in the magnitudes of the reverseflow velocities near the ground and in the upward motion near the upstream wall. A marked transition occurs at Fr ∼ 1, where the single dominant vortex, existing at higher Fr values, weakens and moves upwards whilst a lower region of relatively stagnant flow appears. This transition had previously been observed in numerical model predictions but at a Fr at least an order of magnitude higher

HEATING AND ACCELERATION OF THE FAST SOLAR WIND BY ALFVÉN WAVE TURBULENCE

Energy Technology Data Exchange (ETDEWEB)

Van Ballegooijen, A. A.; Asgari-Targhi, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2016-04-20

We present numerical simulations of reduced magnetohydrodynamic (RMHD) turbulence in a magnetic flux tube at the center of a polar coronal hole. The model for the background atmosphere is a solution of the momentum equation and includes the effects of wave pressure on the solar wind outflow. Alfvén waves are launched at the coronal base and reflect at various heights owing to variations in Alfvén speed and outflow velocity. The turbulence is driven by nonlinear interactions between the counterpropagating Alfvén waves. Results are presented for two models of the background atmosphere. In the first model the plasma density and Alfvén speed vary smoothly with height, resulting in minimal wave reflections and low-energy dissipation rates. We find that the dissipation rate is insufficient to maintain the temperature of the background atmosphere. The standard phenomenological formula for the dissipation rate significantly overestimates the rate derived from our RMHD simulations, and a revised formula is proposed. In the second model we introduce additional density variations along the flux tube with a correlation length of 0.04 R {sub ⊙} and with relative amplitude of 10%. These density variations simulate the effects of compressive MHD waves on the Alfvén waves. We find that such variations significantly enhance the wave reflection and thereby the turbulent dissipation rates, producing enough heat to maintain the background atmosphere. We conclude that interactions between Alfvén and compressive waves may play an important role in the turbulent heating of the fast solar wind.

Control Mechanisms of the Electron Heat Flux in the Solar Wind: Observations in Comparison to Numerical Simulations

Science.gov (United States)

Stverak, S.; Hellinger, P.; Landi, S.; Travnicek, P. M.; Maksimovic, M.

2017-12-01

Recent understanding of the heat transport and dissipation in the expanding solar wind propose number of complex control mechanisms down to the electron kinetic scales. We investigate the evolution of electron heat flux properties and constraints along the expansion using in situ observations from Helios spacecraft in comparison to numerical kinetic simulations. In particular we focus on the roles of Coulomb collisions and wave-particle interactions in shaping the electron velocity distribution functions and thus controlling the heat transported by the electron heat flux. We show the general evolution of the electron heat flux to be driven namely by the Coulomb collisions. Locally we demonstrate the wave-particle interactions related to the kinetic plasma instabilities to be providing effective constraints in case of extreme heat flux levels.

Solar/electric heating systems for the future energy system

DEFF Research Database (Denmark)

Furbo, Simon; Dannemand, Mark; Perers, Bengt

elements/heat pump, advanced heat storage tanks and advanced control systems. Heat is produced by solar collectors in sunny periods and by electrical heating elements/heat pump. The electrical heating elements/heat pump will be in operation in periods where the heat demand cannot be covered by solar energy....... The aim is to use the auxiliary heating units when the electricity price is low, e.g. due to large electricity production by wind turbines. The unit is equipped with an advanced control system where the control of the auxiliary heating is based on forecasts of the electricity price, the heat demand...

Ion acoustic waves and related plasma observations in the solar wind

International Nuclear Information System (INIS)

Gurnett, D.A.; Marsch, E.; Pilipp, W.; Schwenn, R.; Rosenbauer, H.

1979-01-01

This paper presents an investigation of solar wind ion acoustic waves and their relationship to the macroscopic and microscopic characteristics of the solar wind plasma. Comparisons with the overall solar wind corotational structure show that the most intense ion acoustic waves usually occur in the low-velocity regions ahead of high-speed solar wind streams. Of the detailed plasma parameters investigated, the ion acoustic wave intensities are found to be most closely correlated with the electron to proton temperature ratio T/sub e//T/sub p/ and with the electron heat flux. Investigations of the detailed electron and proton distribution functions also show that the ion acoustic waves usually occur in regions with highly non-Maxwellian distributions characteristic of double-proton streams. The distribution functions for the double-proton streams are usually not resolved into two clearly defined peaks, but rather they appear as a broad shoulder on the main proton distribution. Two main mechanisms, an electron heat flux instability and a double-ion beam instability, are considered for generating the ion-acoustic-like waves observed in the solar wind. Both mechanisms have favorable and unfavorable features. The electron heat flux mechanism can account for the observed waves at moderate to large ratios of T/sub e//T/sub p/ but has problems when T/sub e//T/sub p/ is small, as sometimes occurs. The ion beam instability appears to provide more flexibility on the T/sub e//T/sub p/ ratio; however detailed comparisons using observed distribution functions indicate that the ion beam mode is usually stable. Possible resolutions of these difficulties are discussed

Geometry of solar corona expansion and solar wind parameters

International Nuclear Information System (INIS)

Krajnev, M.B.

1980-01-01

The character of the parameter chanqe of solar wind plasma in the region of the Earth orbit is studied. The main regularities in the parametep behaviour of solar wind (plasma velocity and density) are qualitatively explained in the framework of a model according to which solar corona expansion stronqly differs from radial expansion, that is: the solar wind current lines are focused towards helioequator during the period of low solar activity with gradual transfer to radial expansion during the years of high solar activity. It is shown that the geometry of the solar wind current tubes and its change with the solar activity cycle can not serve an explanation of the observed change of the solar wind parameters

Observations of magnetic pumping in the solar wind using MMS data

Science.gov (United States)

Lichko, Emily; Egedal, Jan; Daughton, William; Kasper, Justin

2017-10-01

The turbulent cascade is believed to play an important role in the energization of the solar wind plasma. However, there are characteristics of the solar wind that are not readily explained by the cascade, such as the power-law distribution of the solar wind speed. Starting from the drift kinetic equation, we have derived a magnetic pumping model, similar to the magnetic pumping well-known in fusion research, that provides an explanation for these features. In this model, particles are heated by the largest scale turbulent fluctuations, providing a complementary heating mechanism to the turbulent cascade. We will present observations of this mechanism in the bow shock region using data from the Magnetospheric MultiScale mission. This research was conducted with support from National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168, as well as from NSF Award 1404166 and NASA award NNX15AJ73G.

77 FR 61597 - Avalon Wind, LLC; Avalon Wind 2, LLC; Catalina Solar, LLC; Catalina Solar 2, LLC; Pacific Wind...

Science.gov (United States)

2012-10-10

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL12-109-000] Avalon Wind, LLC; Avalon Wind 2, LLC; Catalina Solar, LLC; Catalina Solar 2, LLC; Pacific Wind Lessee, LLC; Pacific Wind 2, LLC; Valentine Solar, LLC; EDF Renewable Development, Inc.; Notice of Petition for Declaratory...

Air emissions due to wind and solar power.

Science.gov (United States)

Katzenstein, Warren; Apt, Jay

2009-01-15

Renewables portfolio standards (RPS) encourage large-scale deployment of wind and solar electric power. Their power output varies rapidly, even when several sites are added together. In many locations, natural gas generators are the lowest cost resource available to compensate for this variability, and must ramp up and down quickly to keep the grid stable, affecting their emissions of NOx and CO2. We model a wind or solar photovoltaic plus gas system using measured 1-min time-resolved emissions and heat rate data from two types of natural gas generators, and power data from four wind plants and one solar plant. Over a wide range of renewable penetration, we find CO2 emissions achieve approximately 80% of the emissions reductions expected if the power fluctuations caused no additional emissions. Using steam injection, gas generators achieve only 30-50% of expected NOx emissions reductions, and with dry control NOx emissions increase substantially. We quantify the interaction between state RPSs and NOx constraints, finding that states with substantial RPSs could see significant upward pressure on NOx permit prices, if the gas turbines we modeled are representative of the plants used to mitigate wind and solar power variability.

Variation of the solar wind velocity following solar flares

International Nuclear Information System (INIS)

Huang, Y.; Lee, Y.

1975-01-01

By use of the superposed epoch method, changes in the solar wind velocity following solar flares have been investigated by using the solar wind velocity data obtained by Pioneer 6 and 7 and Vela 3, 4, and 5 satellites. A significant increase of the solar wind velocity has been found on the second day following importance 3 solar flares and on the third day following importance 2 solar flares. No significant increase of the solar wind velocity has been found for limb flares. (auth)

Wind and solar resource data sets: Wind and solar resource data sets

Energy Technology Data Exchange (ETDEWEB)

Clifton, Andrew [National Renewable Energy Laboratory, Golden CO USA; Hodge, Bri-Mathias [National Renewable Energy Laboratory, Golden CO USA; Power Systems Engineering Center, National Renewable Energy Laboratory, Golden CO USA; Draxl, Caroline [National Renewable Energy Laboratory, Golden CO USA; National Wind Technology Center, National Renewable Energy Laboratory, Golden CO USA; Badger, Jake [Department of Wind Energy, Danish Technical University, Copenhagen Denmark; Habte, Aron [National Renewable Energy Laboratory, Golden CO USA; Power Systems Engineering Center, National Renewable Energy Laboratory, Golden CO USA

2017-12-05

The range of resource data sets spans from static cartography showing the mean annual wind speed or solar irradiance across a region to high temporal and high spatial resolution products that provide detailed information at a potential wind or solar energy facility. These data sets are used to support continental-scale, national, or regional renewable energy development; facilitate prospecting by developers; and enable grid integration studies. This review first provides an introduction to the wind and solar resource data sets, then provides an overview of the common methods used for their creation and validation. A brief history of wind and solar resource data sets is then presented, followed by areas for future research.

Solar wind radiation damage in lunar dust grains and the characteristics of the ancient solar wind

International Nuclear Information System (INIS)

Borg, J.; Chaumont, J.

1980-01-01

Current understanding of the exposure history of lunar dust grains to the ancient solar wind is reviewed, the work being based mostly on a Monte Carlo statistical code, describing the 'gardening' effects of the meteorite bombardment in the lunar regolith, and on analytical models, yielding the lifetimes of the grains against various types of destruction processes. Families of lunar dust grains are identified, and evidence is presented showing that lunar dust grains were not partially shielded from solar wind ions. Results of solar wind simulation experiments are used to interpret the thickness distribution of the amorphous coatings of solar wind radiation-damaged material observed on 1-micron lunar dust grains. It is argued that such distributions reflect the speed distribution of the ancient solar wind as averaged over periods of approximately 5000 years in duration, and that the ancient solar wind is less energetic than the present day solar wind

Transient flows of the solar wind associated with small-scale solar activity in solar minimum

Science.gov (United States)

Slemzin, Vladimir; Veselovsky, Igor; Kuzin, Sergey; Gburek, Szymon; Ulyanov, Artyom; Kirichenko, Alexey; Shugay, Yulia; Goryaev, Farid

The data obtained by the modern high sensitive EUV-XUV telescopes and photometers such as CORONAS-Photon/TESIS and SPHINX, STEREO/EUVI, PROBA2/SWAP, SDO/AIA provide good possibilities for studying small-scale solar activity (SSA), which is supposed to play an important role in heating of the corona and producing transient flows of the solar wind. During the recent unusually weak solar minimum, a large number of SSA events, such as week solar flares, small CMEs and CME-like flows were observed and recorded in the databases of flares (STEREO, SWAP, SPHINX) and CMEs (LASCO, CACTUS). On the other hand, the solar wind data obtained in this period by ACE, Wind, STEREO contain signatures of transient ICME-like structures which have shorter duration (<10h), weaker magnetic field strength (<10 nT) and lower proton temperature than usual ICMEs. To verify the assumption that ICME-like transients may be associated with the SSA events we investigated the number of weak flares of C-class and lower detected by SPHINX in 2009 and STEREO/EUVI in 2010. The flares were classified on temperature and emission measure using the diagnostic means of SPHINX and Hinode/EIS and were confronted with the parameters of the solar wind (velocity, density, ion composition and temperature, magnetic field, pitch angle distribution of the suprathermal electrons). The outflows of plasma associated with the flares were identified by their coronal signatures - CMEs (only in few cases) and dimmings. It was found that the mean parameters of the solar wind projected to the source surface for the times of the studied flares were typical for the ICME-like transients. The results support the suggestion that weak flares can be indicators of sources of transient plasma flows contributing to the slow solar wind at solar minimum, although these flows may be too weak to be considered as separate CMEs and ICMEs. The research leading to these results has received funding from the European Union’s Seventh Programme

TURBULENCE IN THE SUB-ALFVENIC SOLAR WIND DRIVEN BY REFLECTION OF LOW-FREQUENCY ALFVEN WAVES

International Nuclear Information System (INIS)

Verdini, A.; Velli, M.; Buchlin, E.

2009-01-01

We study the formation and evolution of a turbulent spectrum of Alfven waves driven by reflection off the solar wind density gradients, starting from the coronal base up to 17 solar radii, well beyond the Alfvenic critical point. The background solar wind is assigned and two-dimensional shell models are used to describe nonlinear interactions. We find that the turbulent spectra are influenced by the nature of the reflected waves. Close to the base, these give rise to a flatter and steeper spectrum for the outgoing and reflected waves, respectively. At higher heliocentric distance both spectra evolve toward an asymptotic Kolmogorov spectrum. The turbulent dissipation is found to account for at least half of the heating required to sustain the background imposed solar wind and its shape is found to be determined by the reflection-determined turbulent heating below 1.5 solar radii. Therefore, reflection and reflection-driven turbulence are shown to play a key role in the acceleration of the fast solar wind and origin of the turbulent spectrum found at 0.3 AU in the heliosphere.

Solar wind classification from a machine learning perspective

Science.gov (United States)

Heidrich-Meisner, V.; Wimmer-Schweingruber, R. F.

2017-12-01

It is a very well known fact that the ubiquitous solar wind comes in at least two varieties, the slow solar wind and the coronal hole wind. The simplified view of two solar wind types has been frequently challenged. Existing solar wind categorization schemes rely mainly on different combinations of the solar wind proton speed, the O and C charge state ratios, the Alfvén speed, the expected proton temperature and the specific proton entropy. In available solar wind classification schemes, solar wind from stream interaction regimes is often considered either as coronal hole wind or slow solar wind, although their plasma properties are different compared to "pure" coronal hole or slow solar wind. As shown in Neugebauer et al. (2016), even if only two solar wind types are assumed, available solar wind categorization schemes differ considerably for intermediate solar wind speeds. Thus, the decision boundary between the coronal hole and the slow solar wind is so far not well defined.In this situation, a machine learning approach to solar wind classification can provide an additional perspective.We apply a well-known machine learning method, k-means, to the task of solar wind classification in order to answer the following questions: (1) How many solar wind types can reliably be identified in our data set comprised of ten years of solar wind observations from the Advanced Composition Explorer (ACE)? (2) Which combinations of solar wind parameters are particularly useful for solar wind classification?Potential subtypes of slow solar wind are of particular interest because they can provide hints of respective different source regions or release mechanisms of slow solar wind.

Prospects for jointly using solar and wind energy for heat supply and hot water supply to private houses under the conditions of Baku

International Nuclear Information System (INIS)

Salamov, O. M.; Aliev, F. F.

2013-01-01

This paper analyzes the discovery of the potential for jointly using solar and wind energy for heat supply (HS) and hot water supply (HWS) to a one-family private house located in the Apsheron Peninsula. (authors)

Performance Analysis of a Savonius Wind Turbine in the Solar Integrated Rotor House

Directory of Open Access Journals (Sweden)

ABDUL LATIFMANGANHAR

2017-07-01

Full Text Available Rooftop, building integrated and building augmented micro wind systems have the potential for small scale power generation in the built environment. Nevertheless, the expansion of micro wind technology is very slow and its market is strongly affected by the low efficiency of conventional wind generators. WAG-RH (Wind Accelerating and Guiding Rotor House which is a new technique introduced to enhance the efficiency of vertical axis rotor. The present study utilizes other green energy element by integrating the WAG-RH with a solar heating system. In this effort roof of the WAG-RH has been utilized to heat air through micro solar chimney for creating buoyancy effect in the air flow channel at rotor zone in the WAG-RH. The integration is capable of improving the performance of rotor setup in the WAG-RH as well as providing hot air with sufficient air mass flow rate for space heating. The WAG-RH had brought about 138% increase in the performance coefficient(Cp of conventional three bladed Savonius rotor, whereas solar integrated WAG-RH has contributed 162% increase in the Cp of the same rotor.

Performance analysis of a savonius wind turbine in the solar integrated rotor house

International Nuclear Information System (INIS)

Manganhar, A.L.

2017-01-01

Rooftop, building integrated and building augmented micro wind systems have the potential for small scale power generation in the built environment. Nevertheless, the expansion of micro wind technology is very slow and its market is strongly affected by the low efficiency of conventional wind generators. WAG-RH (Wind Accelerating and Guiding Rotor House) which is a new technique introduced to enhance the efficiency of vertical axis rotor. The present study utilizes other green energy element by integrating the WAG-RH with a solar heating system. In this effort roof of the WAG-RH has been utilized to heat air through micro solar chimney for creating buoyancy effect in the air flow channel at rotor zone in the WAG-RH. The integration is capable of improving the performance of rotor setup in the WAG-RH as well as providing hot air with sufficient air mass flow rate for space heating. The WAG-RH had brought about 138% increase in the performance coefficient(Cp) of conventional three bladed Savonius rotor, whereas solar integrated WAG-RH has contributed 162% increase in the Cp of the same rotor. (author)

Dynamics of Intense Currents in the Solar Wind

Science.gov (United States)

Artemyev, Anton V.; Angelopoulos, Vassilis; Halekas, Jasper S.; Vinogradov, Alexander A.; Vasko, Ivan Y.; Zelenyi, Lev M.

2018-06-01

Transient currents in the solar wind are carried by various magnetic field discontinuities that contribute significantly to the magnetic field fluctuation spectrum. Internal instabilities and dynamics of these discontinuities are believed to be responsible for magnetic field energy dissipation and corresponding charged particle acceleration and heating. Accurate modeling of these phenomena requires detailed investigation of transient current formation and evolution. By examining such evolution using a unique data set compiled from observations of the same solar wind flow by two spacecraft at Earth’s and Mars’s orbits, we show that it consists of several processes: discontinuity thinning (decrease in thickness normalized by the ion inertial length), intensification of currents normalized to the proton thermal current (i.e., the product of proton charge, density, and thermal velocity), and increase in the compressional component of magnetic field variations across discontinuities. The significant proton temperature variation around most observed discontinuities indicates possible proton heating. Plasma velocity jumps across the discontinuities are well correlated with Alfvén velocity changes. We discuss possible explanations of the observed discontinuity evolution. We also compare the observed evolution with predictions of models describing discontinuity formation due to Alfvén wave steepening. Our results show that discontinuity modeling likely requires taking into account both the effects of nonlinear Alfvén wave dynamics and solar wind expansion.

Solar wind structure out of the ecliptic plane over solar cycles

Science.gov (United States)

Sokol, J. M.; Bzowski, M.; Tokumaru, M.

2017-12-01

Sun constantly emits a stream of plasma known as solar wind. Ground-based observations of the solar wind speed through the interplanetary scintillations (IPS) of radio flux from distant point sources and in-situ measurements by Ulysses mission revealed that the solar wind flow has different characteristics depending on the latitude. This latitudinal structure evolves with the cycle of solar activity. The knowledge on the evolution of solar wind structure is important for understanding the interaction between the interstellar medium surrounding the Sun and the solar wind, which is responsible for creation of the heliosphere. The solar wind structure must be taken into account in interpretation of most of the observations of heliospheric energetic neutral atoms, interstellar neutral atoms, pickup ions, and heliospheric backscatter glow. The information on the solar wind structure is not any longer available from direct measurements after the termination of Ulysses mission and the only source of the solar wind out of the ecliptic plane is the IPS observations. However, the solar wind structure obtained from this method contains inevitable gaps in the time- and heliolatitude coverage. Sokół et al 2015 used the solar wind speed data out of the ecliptic plane retrieved from the IPS observations performed by Institute for Space-Earth Environmental Research (Nagoya University, Japan) and developed a methodology to construct a model of evolution of solar wind speed and density from 1985 to 2013 that fills the data gaps. In this paper we will present a refined model of the solar wind speed and density structure as a function of heliographic latitude updated by the most recent data from IPS observations. And we will discuss methods of extrapolation of the solar wind structure out of the ecliptic plane for the past solar cycles, when the data were not available, as well as forecasting for few years upward.

ISOTOPIC MASS FRACTIONATION OF SOLAR WIND: EVIDENCE FROM FAST AND SLOW SOLAR WIND COLLECTED BY THE GENESIS MISSION

International Nuclear Information System (INIS)

Heber, Veronika S.; Baur, Heinrich; Wieler, Rainer; Bochsler, Peter; McKeegan, Kevin D.; Neugebauer, Marcia; Reisenfeld, Daniel B.; Wiens, Roger C.

2012-01-01

NASA's Genesis space mission returned samples of solar wind collected over ∼2.3 years. We present elemental and isotopic compositions of He, Ne, and Ar analyzed in diamond-like carbon targets from the slow and fast solar wind collectors to investigate isotopic fractionation processes during solar wind formation. The solar wind provides information on the isotopic composition for most volatile elements for the solar atmosphere, the bulk Sun and hence, on the solar nebula from which it formed 4.6 Ga ago. Our data reveal a heavy isotope depletion in the slow solar wind compared to the fast wind composition by 63.1 ± 2.1 per mille for He, 4.2 ± 0.5 per mille amu –1 for Ne and 2.6 ± 0.5 per mille amu –1 for Ar. The three Ne isotopes suggest that isotopic fractionation processes between fast and slow solar wind are mass dependent. The He/H ratios of the collected slow and fast solar wind samples are 0.0344 and 0.0406, respectively. The inefficient Coulomb drag model reproduces the measured isotopic fractionation between fast and slow wind. Therefore, we apply this model to infer the photospheric isotopic composition of He, Ne, and Ar from our solar wind data. We also compare the isotopic composition of oxygen and nitrogen measured in the solar wind with values of early solar system condensates, probably representing solar nebula composition. We interpret the differences between these samples as being due to isotopic fractionation during solar wind formation. For both elements, the magnitude and sign of the observed differences are in good agreement with the values predicted by the inefficient Coulomb drag model.

ISOTOPIC MASS FRACTIONATION OF SOLAR WIND: EVIDENCE FROM FAST AND SLOW SOLAR WIND COLLECTED BY THE GENESIS MISSION

Energy Technology Data Exchange (ETDEWEB)

Heber, Veronika S.; Baur, Heinrich; Wieler, Rainer [Institute for Geochemistry and Petrology, ETH Zurich, Clausiusstrasse 25, CH-8092 Zurich (Switzerland); Bochsler, Peter [Physikalisches Institut, Universitaet Bern, Sidlerstasse 5, CH-3012 Bern (Switzerland); McKeegan, Kevin D. [Department of Earth and Space Sciences, University of California Los Angeles, 595 Charles Young Drive East, Box 951567, Los Angeles, CA 90095-1567 (United States); Neugebauer, Marcia [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092 (United States); Reisenfeld, Daniel B. [Department of Physics and Astronomy, University of Montana, Missoula, MT 59812 (United States); Wiens, Roger C., E-mail: heber@ess.ucla.edu [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2012-11-10

NASA's Genesis space mission returned samples of solar wind collected over {approx}2.3 years. We present elemental and isotopic compositions of He, Ne, and Ar analyzed in diamond-like carbon targets from the slow and fast solar wind collectors to investigate isotopic fractionation processes during solar wind formation. The solar wind provides information on the isotopic composition for most volatile elements for the solar atmosphere, the bulk Sun and hence, on the solar nebula from which it formed 4.6 Ga ago. Our data reveal a heavy isotope depletion in the slow solar wind compared to the fast wind composition by 63.1 {+-} 2.1 per mille for He, 4.2 {+-} 0.5 per mille amu{sup -1} for Ne and 2.6 {+-} 0.5 per mille amu{sup -1} for Ar. The three Ne isotopes suggest that isotopic fractionation processes between fast and slow solar wind are mass dependent. The He/H ratios of the collected slow and fast solar wind samples are 0.0344 and 0.0406, respectively. The inefficient Coulomb drag model reproduces the measured isotopic fractionation between fast and slow wind. Therefore, we apply this model to infer the photospheric isotopic composition of He, Ne, and Ar from our solar wind data. We also compare the isotopic composition of oxygen and nitrogen measured in the solar wind with values of early solar system condensates, probably representing solar nebula composition. We interpret the differences between these samples as being due to isotopic fractionation during solar wind formation. For both elements, the magnitude and sign of the observed differences are in good agreement with the values predicted by the inefficient Coulomb drag model.

Solar wind structure suggested by bimodal correlations of solar wind speed and density between the spacecraft SOHO and Wind

Science.gov (United States)

Ogilvie, K. W.; Coplan, M. A.; Roberts, D. A.; Ipavich, F.

2007-08-01

We calculate the cross-spacecraft maximum lagged-cross-correlation coefficients for 2-hour intervals of solar wind speed and density measurements made by the plasma instruments on the Solar and Heliospheric Observatory (SOHO) and Wind spacecraft over the period from 1996, the minimum of solar cycle 23, through the end of 2005. During this period, SOHO was located at L1, about 200 R E upstream from the Earth, while Wind spent most of the time in the interplanetary medium at distances of more than 100 R E from the Earth. Yearly histograms of the maximum, time-lagged correlation coefficients for both the speed and density are bimodal in shape, suggesting the existence of two distinct solar wind regimes. The larger correlation coefficients we suggest are due to structured solar wind, including discontinuities and shocks, while the smaller are likely due to Alfvénic turbulence. While further work will be required to firmly establish the physical nature of the two populations, the results of the analysis are consistent with a solar wind that consists of turbulence from quiet regions of the Sun interspersed with highly filamentary structures largely convected from regions in the inner solar corona. The bimodal appearance of the distributions is less evident in the solar wind speed than in the density correlations, consistent with the observation that the filamentary structures are convected with nearly constant speed by the time they reach 1 AU. We also find that at solar minimum the fits for the density correlations have smaller high-correlation components than at solar maximum. We interpret this as due to the presence of more relatively uniform Alfvénic regions at solar minimum than at solar maximum.

Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind Current Sheets

Science.gov (United States)

Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris

2013-01-01

A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.

Dissipation and heating in solar wind turbulence: from the macro to the micro and back again.

Science.gov (United States)

Kiyani, Khurom H; Osman, Kareem T; Chapman, Sandra C

2015-05-13

The past decade has seen a flurry of research activity focused on discerning the physics of kinetic scale turbulence in high-speed astrophysical plasma flows. By 'kinetic' we mean spatial scales on the order of or, in particular, smaller than the ion inertial length or the ion gyro-radius--the spatial scales at which the ion and electron bulk velocities decouple and considerable change can be seen in the ion distribution functions. The motivation behind most of these studies is to find the ultimate fate of the energy cascade of plasma turbulence, and thereby the channels by which the energy in the system is dissipated. This brief Introduction motivates the case for a themed issue on this topic and introduces the topic of turbulent dissipation and heating in the solar wind. The theme issue covers the full breadth of studies: from theory and models, massive simulations of these models and observational studies from the highly rich and vast amount of data collected from scores of heliospheric space missions since the dawn of the space age. A synopsis of the theme issue is provided, where a brief description of all the contributions is discussed and how they fit together to provide an over-arching picture on the highly topical subject of dissipation and heating in turbulent collisionless plasmas in general and in the solar wind in particular. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Solar wind flows associated with hot heavy ions

International Nuclear Information System (INIS)

Fenimore, E.E.

1980-05-01

Solar wind heavy ion spectra measured with the Vela instrumentation have been studied with the goal of determining the solar origins of various solar wind structures which contain anomalously high ionization states. Since the ionization states freeze-in close to the sun they are good indicators of the plasma conditions in the low and intermediate corona. Heavy ion spectra from three different periods throughout the solar cycle have been analyzed. These data are consistent with freezing-in temperatures ranging from approx. 1.5 x 10 6 K to higher than 9 x 10 6 . The spectra indicating hot coronal conditions occur in roughly 1/7 of all measurements and almost exclusively in postshock flows (PSFs), nonshock related helium abundance enhancements (HAEs), or noncompressive density enhancements (NCDEs). The PSFs and HAEs are both probably interplanetary manifestations of solar flares. The observation of several flare-related HAEs which were not preceded by an interplanetary shock suggests that the flare-heated plasma can evolve into the solar wind without producing a noticeable shock at 1 AU. The NCDEs with hot heavy ions differ from the PSF-HAEs in several ways implying that they evolve from events or places with lower temperatures and less energy than those associated with the flares, but with higher temperatures and densities than the quiet corona. Active regions, coronal mass ejections, and equatorial streamers are possible sources for the NCDEs with spectra indicating hot coronal conditions. These events owe their enhanced densities to coronal processes as opposed to interplanetary dynamical processes. Models of the solar wind expansion demonstrate how some NCDEs can have extreme, nonequilibrium ionization distributions

Tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control

Science.gov (United States)

Prikryl, Paul; Bruntz, Robert; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel

2018-06-01

Occurrence of severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system is investigated. It is observed that significant snowfall, wind and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur within a few days after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., 2009, 2016) is corroborated for the southern hemisphere. Cases of severe weather events are examined in the context of the magnetosphere-ionosphere-atmosphere (MIA) coupling. Physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., 1990) reveal that propagating waves originating in the lower thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere and initiate convection to form cloud/precipitation bands. It is primarily the energy provided by release of latent heat that leads to intensification of storms. These results indicate that vertical coupling in the atmosphere exerts downward control from solar wind to the lower atmospheric levels influencing tropospheric weather development.

Early time interaction of lithium ions with the solar wind in the AMPTE mission

International Nuclear Information System (INIS)

Lui, A.T.Y.; Goodrich, C.C.; Mankofsky, A.; Papadopoulos, K.

1986-01-01

The early time interaction of an artificially injected lithium cloud with the solar wind is simulated with a one-dimensional hybrid code. Simulation results indicate that the lithium cloud presents an obstacle to the solar wind flow, forming a shock-like interaction region. Several notable features are found: (1) The magnetic field is enhanced up to a factor of about 6 followed by a magnetic cavity downstream. (2) Solar wind ions are slowed down inside the lithium cloud, with substantial upstream reflection. (3) Most of the lithium ions gradually pick up the velocity of the solar wind and move downstream. (4) Intense and short-wavelength electric fields exist ahead of the interaction region. (5) Strong electron heating occurs within the lithium clouds. (6) The convection electric field in the in the solar wind is modulated in the interaction region. The simulation results are in remarkable agreement with in situ spacecraft measurements made during lithium releases in the solar wind by the AMPTE (Active magnetospheric Particle Tracer Explorers) Program

Temporal and radial variation of the solar wind temperature-speed relationship

Science.gov (United States)

Elliott, H. A.; Henney, C. J.; McComas, D. J.; Smith, C. W.; Vasquez, B. J.

2012-09-01

The solar wind temperature (T) and speed (V) are generally well correlated at ˜1 AU, except in Interplanetary Coronal Mass Ejections where this correlation breaks down. We perform a comprehensive analysis of both the temporal and radial variation in the temperature-speed (T-V) relationship of the non-transient wind, and our analysis provides insight into both the causes of the T-V relationship and the sources of the temperature variability. Often at 1 AU the speed-temperature relationship is well represented by a single linear fit over a speed range spanning both the slow and fast wind. However, at times the fast wind from coronal holes can have a different T-V relationship than the slow wind. A good example of this was in 2003 when there was a very large and long-lived outward magnetic polarity coronal hole at low latitudes that emitted wind with speeds as fast as a polar coronal hole. The long-lived nature of the hole made it possible to clearly distinguish that some holes can have a different T-V relationship. In an earlier ACE study, we found that both the compressions and rarefactions T-V curves are linear, but the compression curve is shifted to higher temperatures. By separating compressions and rarefactions prior to determining the radial profiles of the solar wind parameters, the importance of dynamic interactions on the radial evolution of the solar wind parameters is revealed. Although the T-V relationship at 1 AU is often well described by a single linear curve, we find that the T-V relationship continually evolves with distance. Beyond ˜2.5 AU the differences between the compressions and rarefactions are quite significant and affect the shape of the overall T-V distribution to the point that a simple linear fit no longer describes the distribution well. Since additional heating of the ambient solar wind outside of interaction regions can be associated with Alfvénic fluctuations and the turbulent energy cascade, we also estimate the heating rate

Recent Successes of Wave/Turbulence Driven Models of Solar Wind Acceleration

Science.gov (United States)

Cranmer, S. R.; Hollweg, J. V.; Chandran, B. D.; van Ballegooijen, A. A.

2010-12-01

A key obstacle in the way of producing realistic simulations of the Sun-heliosphere system is the lack of a first-principles understanding of coronal heating. Also, it is still unknown whether the solar wind is "fed" through flux tubes that remain open (and are energized by footpoint-driven wavelike fluctuations) or if mass and energy are input intermittently from closed loops into the open-field regions. In this presentation, we discuss self-consistent models that assume the energy comes from solar Alfven waves that are partially reflected, and then dissipated, by magnetohydrodynamic turbulence. These models have been found to reproduce many of the observed features of the fast and slow solar wind without the need for artificial "coronal heating functions" used by earlier models. For example, the models predict a variation with wind speed in commonly measured ratios of charge states and elemental abundances that agrees with observed trends. This contradicts a commonly held assertion that these ratios can only be produced by the injection of plasma from closed-field regions on the Sun. This presentation also reviews two recent comparisons between the models and empirical measurements: (1) The models successfully predict the amplitude and radial dependence of Faraday rotation fluctuations (FRFs) measured by the Helios probes for heliocentric distances between 2 and 15 solar radii. The FRFs are a particularly sensitive test of turbulence models because they depend not only on the plasma density and Alfven wave amplitude in the corona, but also on the turbulent correlation length. (2) The models predict the correct sense and magnitude of changes seen in the polar high-speed solar wind by Ulysses from the previous solar minimum (1996-1997) to the more recent peculiar minimum (2008-2009). By changing only the magnetic field along the polar magnetic flux tube, consistent with solar and heliospheric observations at the two epochs, the model correctly predicts that the

Characteristics of Solar Wind Density Depletions During Solar Cycles 23 and 24

Directory of Open Access Journals (Sweden)

Keunchan Park

2017-06-01

Full Text Available Solar wind density depletions are phenomena that solar wind density is rapidly decreased and keep the state. They are generally believed to be caused by the interplanetary (IP shocks. However, there are other cases that are hardly associated with IP shocks. We set up a hypothesis for this phenomenon and analyze this study. We have collected the solar wind parameters such as density, speed and interplanetary magnetic field (IMF data related to the solar wind density depletion events during the period from 1996 to 2013 that are obtained with the advanced composition explorer (ACE and the Wind satellite. We also calculate two pressures (magnetic, dynamic and analyze the relation with density depletion. As a result, we found total 53 events and the most these phenomena’s sources caused by IP shock are interplanetary coronal mass ejection (ICME. We also found that solar wind density depletions are scarcely related with IP shock’s parameters. The solar wind density is correlated with solar wind dynamic pressure within density depletion. However, the solar wind density has an little anti-correlation with IMF strength during all events of solar wind density depletion, regardless of the presence of IP shocks. Additionally, In 47 events of IP shocks, we find 6 events that show a feature of blast wave. The quantities of IP shocks are weaker than blast wave from the Sun, they are declined in a short time after increasing rapidly. We thus argue that IMF strength or dynamic pressure are an important factor in understanding the nature of solar wind density depletion. Since IMF strength and solar wind speed varies with solar cycle, we will also investigate the characteristics of solar wind density depletion events in different phases of solar cycle as an additional clue to their physical nature.

Kinetic Properties of Solar Wind Silicon and Iron Ions

Science.gov (United States)

Janitzek, N. P.; Berger, L.; Drews, C.; Wimmer-Schweingruber, R. F.

2017-12-01

Heavy ions with atomic numbers Z>2 account for less than one percent of the solar wind ions. However, serving as test particles with differing mass and charge, they provide a unique experimental approach to major questions of solar and fundamental plasma physics such as coronal heating, the origin and acceleration of the solar wind and wave-particle interaction in magnetized plasma. Yet the low relative abundances of the heavy ions pose substantial challenges to the instrumentation measuring these species with reliable statistics and sufficient time resolution. As a consequence the numbers of independent measurements and studies are small. The Charge Time-Of-Flight (CTOF) mass spectrometer as part of the Charge, ELement and Isotope Analysis System (CELIAS) onboard the SOlar and Heliospheric Observatory (SOHO) is a linear time-of-flight mass spectrometer which was operated at Lagrangian point L1 in 1996 for a few months only, before it suffered an instrument failure. Despite its short operation time, the CTOF sensor measured solar wind heavy ions with excellent charge state separation, an unprecedented cadence of 5 minutes and very high counting statistics, exceeding similar state-of-the-art instruments by a factor of ten. In contrast to earlier CTOF studies which were based on reduced onboard post-processed data, in our current studies we use raw Pulse Height Analysis (PHA) data providing a significantly increased mass, mass-per-charge and velocity resolution. Focussing on silicon and iron ion measurements, we present an overview of our findings on (1) short time behavior of heavy ion 1D radial velocity distribution functions, (2) differential streaming between heavy ions and solar wind bulk protons, (3) kinetic temperatures of heavy ions. Finally, we compare the CTOF results with measurements of the Solar Wind Ion Composition Spectrometer (SWICS) instrument onboard the Advanced Composition Explorer (ACE).

Proton thermal energetics in the solar wind: Helios reloaded

Czech Academy of Sciences Publication Activity Database

Hellinger, Petr; Trávníček, P.; Štverák, Štěpán; Matteini, L.; Velli, M.

2013-01-01

Roč. 118, č. 4 (2013), s. 1351-1365 ISSN 2169-9380 Institutional support: RVO:68378289 Keywords : solar wind * proton energetics * turbulent heating Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.440, year: 2013 http://onlinelibrary.wiley.com/doi/10.1002/jgra.50107/abstract

Multicriteria GIS modeling of wind and solar farms in Colorado

Energy Technology Data Exchange (ETDEWEB)

Janke, Jason R. [Metropolitan State College of Denver, Department of Earth and Atmospheric Sciences, CB 22 P.O. Box 173362-22, Denver, CO 80217-3362 (United States)

2010-10-15

The majority of electricity and heat in Colorado comes from coal and natural gas; however, renewable energy sources will play an integral role in the state's energy future. Colorado is the 11th windiest state and has more than 250 sunny days per year. The objectives of this research are to: 1) determine which landcover classes are affiliated with high wind and solar potential; and 2) identify areas that are suitable for wind and solar farms using multicriteria GIS modelling techniques. Renewable potential (NREL wind speed measurements at 50 m above the ground and NREL annual insolation data), landcover, population density, federal lands, and distance to roads, transmission lines, and cities were reclassified according to their suitability. Each was assigned weights based on their relative importance to one another. Superb wind classes are located in high alpine areas. Unfortunately, these areas are not suitable for large-scale wind farm development due to their inaccessibility and location within a sensitive ecosystem. Federal lands have low wind potential. According to the GIS model, ideal areas for wind farm development are located in northeastern Colorado. About 41 850 km{sup 2} of the state has model scores that are in the 90-100% range. Although annual solar radiation varies slightly, inter-mountain areas receive the most insolation. As far as federal lands, Indian reservations have the greatest solar input. The GIS model indicates that ideal areas for solar development are located in northwestern Colorado and east of Denver. Only 191 km{sup 2} of the state had model scores that were in the 90-100% range. These results suggest that the variables used in this analysis have more of an effect at eliminating non-suitable areas for large-scale solar farms; a greater area exists for suitable wind farms. However, given the statewide high insolation values with minimal variance, solar projects may be better suited for small-scale residential or commercial

THE CONTRIBUTION OF CORONAL JETS TO THE SOLAR WIND

Energy Technology Data Exchange (ETDEWEB)

Lionello, R.; Török, T.; Titov, V. S.; Mikić, Z.; Linker, J. A. [Predictive Science Inc., 9990 Mesa Rim Road, Suite 170, San Diego, CA 92121 (United States); Leake, J. E.; Linton, M. G., E-mail: lionel@predsci.com [US Naval Research Laboratory 4555 Overlook Avenue, SW Washington, DC 20375 (United States)

2016-11-01

Transient collimated plasma eruptions in the solar corona, commonly known as coronal (or X-ray) jets, are among the most interesting manifestations of solar activity. It has been suggested that these events contribute to the mass and energy content of the corona and solar wind, but the extent of these contributions remains uncertain. We have recently modeled the formation and evolution of coronal jets using a three-dimensional (3D) magnetohydrodynamic (MHD) code with thermodynamics in a large spherical domain that includes the solar wind. Our model is coupled to 3D MHD flux-emergence simulations, i.e., we use boundary conditions provided by such simulations to drive a time-dependent coronal evolution. The model includes parametric coronal heating, radiative losses, and thermal conduction, which enables us to simulate the dynamics and plasma properties of coronal jets in a more realistic manner than done so far. Here, we employ these simulations to calculate the amount of mass and energy transported by coronal jets into the outer corona and inner heliosphere. Based on observed jet-occurrence rates, we then estimate the total contribution of coronal jets to the mass and energy content of the solar wind to (0.4–3.0)% and (0.3–1.0)%, respectively. Our results are largely consistent with the few previous rough estimates obtained from observations, supporting the conjecture that coronal jets provide only a small amount of mass and energy to the solar wind. We emphasize, however, that more advanced observations and simulations (including parametric studies) are needed to substantiate this conjecture.

Thermal analyses of solar swimming pool heating in Pakistan

International Nuclear Information System (INIS)

Ahmad, I.

2011-01-01

Hotels and swimming clubs in Pakistan pay huge gas bills for heating Swimming pools in winter. Winter days in most parts of Pakistan remain sunny and unglazed low cost solar collectors may be used to extend the swimming season. Installing the pool in a wind-protected area, which receives unobstructed solar radiation, may further reduce the size of the solar collectors required to heat the swimming pools. The pools should be covered with plastic sheet to eliminate evaporative heat losses and to prevent dust and tree leaves falling in the pool. The results of the thermal analysis show that in some parts of the country, a solar exposed pool can maintain comfortable temperature simply by using a plastic sheet on the pool surface. On the other hand, there are cities where solar collector array equal to twice the surface area of the pool is required to keep desired temperature in winter. (author)

Solar wind stagnation near comets

International Nuclear Information System (INIS)

Galeev, A.A.; Cravens, T.E.; Gombosi, T.I.

1983-03-01

The nature of the solar wind flow near comets is examined analytically. In particular, the typical values for the stagnation pressure and magnetic barrier strength are estimated, taking into account the magnetic field line tension and the charge exchange cooling of the mass loaded solar wind. Knowledge of the strength of the magnetic barrier is required in order to determine the location of the contact discontinuity which separates the contaminated solar wind plasma and the outflowing plasma of the cometary ionosphere. (author)

Optimal Scheduling of Biogas-Solar-Wind Renewable Portfolio for Multi-Carrier Energy Supplies

DEFF Research Database (Denmark)

Zhou, Bin; Xu, Da; Li, Canbing

2018-01-01

the mitigation of renewable intermittency and the efficient utilization of batteries, and a multi-carrier generation scheduling scheme is further presented to dynamically optimize dispatch factors in the coupling matrix for energy-efficient con-version and storage, while different energy demands of end......This paper proposes a multi-source multi-product framework for coupled multi-carrier energy supplies with a biogas-solar-wind hybrid renewable system. In this framework, the biogas-solar-wind complementarities are fully exploited based on digesting thermodynamic effects for the synergetic...... interactions of electricity, gas and heating energy flows, and a coupling matrix is formulated for the modeling of production, conversion, storage, and consumption of different energy carriers. The multi-energy complementarity of biogas-solar-wind renewable portfolio can be utilized to facilitate...

Analysis of the solar/wind resources in Southern Spain for optimal sizing of hybrid solar-wind power generation systems

Science.gov (United States)

Quesada-Ruiz, S.; Pozo-Vazquez, D.; Santos-Alamillos, F. J.; Lara-Fanego, V.; Ruiz-Arias, J. A.; Tovar-Pescador, J.

2010-09-01

A drawback common to the solar and wind energy systems is their unpredictable nature and dependence on weather and climate on a wide range of time scales. In addition, the variation of the energy output may not match with the time distribution of the load demand. This can partially be solved by the use of batteries for energy storage in stand-alone systems. The problem caused by the variable nature of the solar and wind resources can be partially overcome by the use of energy systems that uses both renewable resources in a combined manner, that is, hybrid wind-solar systems. Since both resources can show complementary characteristics in certain location, the independent use of solar or wind systems results in considerable over sizing of the batteries system compared to the use of hybrid solar-wind systems. Nevertheless, to the day, there is no single recognized method for properly sizing these hybrid wind-solar systems. In this work, we present a method for sizing wind-solar hybrid systems in southern Spain. The method is based on the analysis of the wind and solar resources on daily scale, particularly, its temporal complementary characteristics. The method aims to minimize the size of the energy storage systems, trying to provide the most reliable supply.

PHOTOIONIZATION IN THE SOLAR WIND

Energy Technology Data Exchange (ETDEWEB)

Landi, E.; Lepri, S. T., E-mail: elandi@umich.edu [Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

2015-10-20

In this work we investigate the effects of photoionization on the charge state composition of the solar wind. Using measured solar EUV and X-ray irradiance, the Michigan Ionization Code and a model for the fast and slow solar wind, we calculate the evolution of the charge state distribution of He, C, N, O, Ne, Mg, Si, S, and Fe with and without including photoionization for both types of wind. We find that the solar radiation has significant effects on the charge state distribution of C, N, and O, causing the ionization levels of these elements to be higher than without photoionization; differences are largest for oxygen. The ions commonly observed for elements heavier than O are much less affected, except in ICMEs where Fe ions more ionized than 16+ can also be affected by the solar radiation. We also show that the commonly used O{sup 7+}/O{sup 6+} density ratio is the most sensitive to photoionization; this sensitivity also causes the value of this ratio to depend on the phase of the solar cycle. We show that the O{sup 7+}/O{sup 6+} ratio needs to be used with caution for solar wind classification and coronal temperature estimates, and recommend the C{sup 6+}/C{sup 4+} ratio for these purposes.

Solar Wind Earth Exchange Project (SWEEP)

Science.gov (United States)

2016-10-28

highly charged ions of the solar wind. The main challenge in predicting the resultant photon flux in the X-ray energy bands is due to the...Newton, an X-ray astronomical observatory. We use OMNI solar wind conditions, heavy ion composition data from ACE, the Hodges neutral hydrogen model...of SWEEP was to compare theoretical models of X-ray emission in the terrestrial magnetosphere caused by the Solar Wind Charge Exchange

SOLAR WIND HEAVY IONS OVER SOLAR CYCLE 23: ACE/SWICS MEASUREMENTS

International Nuclear Information System (INIS)

Lepri, S. T.; Landi, E.; Zurbuchen, T. H.

2013-01-01

Solar wind plasma and compositional properties reflect the physical properties of the corona and its evolution over time. Studies comparing the previous solar minimum with the most recent, unusual solar minimum indicate that significant environmental changes are occurring globally on the Sun. For example, the magnetic field decreased 30% between the last two solar minima, and the ionic charge states of O have been reported to change toward lower values in the fast wind. In this work, we systematically and comprehensively analyze the compositional changes of the solar wind during cycle 23 from 2000 to 2010 while the Sun moved from solar maximum to solar minimum. We find a systematic change of C, O, Si, and Fe ionic charge states toward lower ionization distributions. We also discuss long-term changes in elemental abundances and show that there is a ∼50% decrease of heavy ion abundances (He, C, O, Si, and Fe) relative to H as the Sun went from solar maximum to solar minimum. During this time, the relative abundances in the slow wind remain organized by their first ionization potential. We discuss these results and their implications for models of the evolution of the solar atmosphere, and for the identification of the fast and slow wind themselves.

The Solar Wind Environment in Time

Science.gov (United States)

Pognan, Quentin; Garraffo, Cecilia; Cohen, Ofer; Drake, Jeremy J.

2018-03-01

We use magnetograms of eight solar analogs of ages 30 Myr–3.6 Gyr obtained from Zeeman Doppler Imaging and taken from the literature, together with two solar magnetograms, to drive magnetohydrodynamical wind simulations and construct an evolutionary scenario of the solar wind environment and its angular momentum loss rate. With observed magnetograms of the radial field strength as the only variant in the wind model, we find that a power-law model fitted to the derived angular momentum loss rate against time, t, results in a spin-down relation Ω ∝ t ‑0.51, for angular speed Ω, which is remarkably consistent with the well-established Skumanich law Ω ∝ t ‑0.5. We use the model wind conditions to estimate the magnetospheric standoff distances for an Earth-like test planet situated at 1 au for each of the stellar cases, and to obtain trends of minimum and maximum wind ram pressure and average ram pressure in the solar system through time. The wind ram pressure declines with time as \\overline{{P}ram}}\\propto {t}2/3, amounting to a factor of 50 or so over the present lifetime of the solar system.

Numerical simulation of wind loads on solar panels

Science.gov (United States)

Su, Kao-Chun; Chung, Kung-Ming; Hsu, Shu-Tsung

2018-05-01

Solar panels mounted on the roof of a building or ground are often vulnerable to strong wind loads. This study aims to investigate wind loads on solar panels using computational fluid dynamic (CFD). The results show good agreement with wind tunnel data, e.g. the streamwise distribution of mean surface pressure coefficient of a solar panel. Wind uplift for solar panels with four aspect ratios is evaluated. The effect of inclined angle and clearance (or height) of a solar panel is addressed. It is found that wind uplift of a solar panel increases when there is an increase in inclined angle and the clearance above ground shows an opposite effect.

Wind and solar resource data sets

DEFF Research Database (Denmark)

Clifton, Andrew; Hodge, Bri-Mathias; Draxl, Caroline

2017-01-01

The range of resource data sets spans from static cartography showing the mean annual wind speed or solar irradiance across a region to high temporal and high spatial resolution products that provide detailed information at a potential wind or solar energy facility. These data sets are used...... to support continental-scale, national, or regional renewable energy development; facilitate prospecting by developers; and enable grid integration studies. This review first provides an introduction to the wind and solar resource data sets, then provides an overview of the common methods used...... for their creation and validation. A brief history of wind and solar resource data sets is then presented, followed by areas for future research. For further resources related to this article, please visit the WIREs website....

Distribution of ionospheric currents induced by the solar wind interaction with Venus

International Nuclear Information System (INIS)

Daniell, R.E. Jr.; Cloutier, P.A.

1977-01-01

The electric currents induced in the atmosphere of a non-magnetic planet such as Venus by the interaction of the solar wind satisfy a generalized Ohm's Law relationship with tensor conductivity. The distribution of these currents within the planetary ionosphere may be calculated by a variational technique which minimizes the Joule heating over the ionospheric volume. In this paper, we present the development of the variational technique, and apply it to a model of the solar wind interaction with Venus. Potential and current distributions are shown, and the use of these distributions in determining convective transport patterns of planetary ions is discussed. (author)

Turbulence and Waves as Sources for the Solar Wind

Science.gov (United States)

Cranmer, S. R.

2008-05-01

Gene Parker's insights from 50 years ago provided the key causal link between energy deposition in the solar corona and the acceleration of solar wind streams. However, the community is still far from agreement concerning the actual physical processes that give rise to this energy. It is still unknown whether the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wavelike fluctuations) or if mass and energy is input more intermittently from closed loops into the open-field regions. No matter the relative importance of reconnections and loop-openings, though, we do know that waves and turbulent motions are present everywhere from the photosphere to the heliosphere, and it is important to determine how they affect the mean state of the plasma. In this presentation, I will give a summary of wave/turbulence models that seem to succeed in explaining the time-steady properties of the corona (and the fast and slow solar wind). The coronal heating and solar wind acceleration in these models comes from anisotropic turbulent cascade, which is driven by the partial reflection of low-frequency Alfven waves propagating along the open magnetic flux tubes. Specifically, a 2D model of coronal holes and streamers at solar minimum reproduces the latitudinal bifurcation of slow and fast streams seen by Ulysses. The radial gradient of the Alfven speed affects where the waves are reflected and damped, and thus whether energy is deposited below or above Parker's critical point. As predicted by earlier studies, a larger coronal expansion factor gives rise to a slower and denser wind, higher temperature at the coronal base, less intense Alfven waves at 1 AU, and correlative trends for commonly measured ratios of ion charge states and FIP-sensitive abundances that are in general agreement with observations. Finally, I will outline the types of future observations that would be most able to test and refine these ideas.

Solar and seasonal dependence of ion frictional heating

Directory of Open Access Journals (Sweden)

J. A. Davies

1999-05-01

Full Text Available Ion frictional heating constitutes one of the principal mechanisms whereby energy, originating in the solar wind, is deposited into the Earth's ionosphere and ultimately the neutral atmosphere. Common programme observations by the EISCAT UHF radar system, spanning the years 1984 to 1995, provide the basis for a comprehensive statistical study of ion frictional heating, results of which are documented in this and a previous paper by the authors. In the present work, the authors demonstrate the solar and seasonal dependence of the universal time distribution of frictional heating, and explain these results with reference to corresponding dependences of the ion velocity. Although EISCAT observes a significant increase in the occurrence of enhanced ion velocities associated with increased solar activity, the latter characterised according to the prevailing 10.7 cm solar flux, this is not reflected to such an extent in the occurrence of frictional heating. It is suggested that this is a consequence of the decreased neutral atmosphere response times associated with active solar conditions, resulting from the higher ionospheric plasma densities present. Seasonal effects on the diurnal distribution of ion frictional heating are well explained by corresponding variations in ionospheric convection, the latter principally a result of geometrical factors. It is noted that, over the entire dataset, the variations in the unperturbed F-region ion temperature, required to implement the identification criterion for ion heating, are highly correlated with model values of thermospheric temperature.Keywords. Ionosphere (auroral ionosphere; ionosphere-atmosphere interactions; plasma temperature and density

Manifestation of solar activity in solar wind particle flux density

International Nuclear Information System (INIS)

Kovalenko, V.A.

1988-01-01

An analysis has been made of the origin of long-term variations in flux density of solar wind particles (nv) for different velocity regimes. The study revealed a relationship of these variations to the area of the polar coronal holes (CH). It is shown that within the framework of the model under development, the main longterm variations of nv are a result of the latitude redistribution of the solar wind mass flux in the heliosphere and are due to changes in the large-scale geometry of the solar plasma flow in the corona. A study has been made of the variations of nv for high speed solar wind streams. It is found that nv in high speed streams which are formed in CH, decreases from minimum to maximum solar activity. The analysis indicates that this decrease is attributable to the magnetic field strength increase in coronal holes. It has been found that periods of rapid global changes of background magnetic fields on the Sun are accompanied by a reconfiguration of coronal magnetic fields, rapid changes in the length of quiescent filaments, and by an increase in the density of the particle flux of a high speed solar wind. It has been established that these periods precede the formation of CH, corresponding to the increase in solar wind velocity near the Earth and to enhancement of the level of geomagnetic disturbance. (author)

A survey of solar wind conditions at 5 AU: a tool for interpreting solar wind-magnetosphere interactions at Jupiter

Energy Technology Data Exchange (ETDEWEB)

Ebert, Robert W. [Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX (United States); Bagenal, Fran [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO (United States); McComas, David J. [Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX (United States); Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX (United States); Fowler, Christopher M., E-mail: rebert@swri.edu [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO (United States)

2014-09-19

We examine Ulysses solar wind and interplanetary magnetic field (IMF) observations at 5 AU for two ~13 month intervals during the rising and declining phases of solar cycle 23 and the predicted response of the Jovian magnetosphere during these times. The declining phase solar wind, composed primarily of corotating interaction regions and high-speed streams, was, on average, faster, hotter, less dense, and more Alfvénic relative to the rising phase solar wind, composed mainly of slow wind and interplanetary coronal mass ejections. Interestingly, none of solar wind and IMF distributions reported here were bimodal, a feature used to explain the bimodal distribution of bow shock and magnetopause standoff distances observed at Jupiter. Instead, many of these distributions had extended, non-Gaussian tails that resulted in large standard deviations and much larger mean over median values. The distribution of predicted Jupiter bow shock and magnetopause standoff distances during these intervals were also not bimodal, the mean/median values being larger during the declining phase by ~1–4%. These results provide data-derived solar wind and IMF boundary conditions at 5 AU for models aimed at studying solar wind-magnetosphere interactions at Jupiter and can support the science investigations of upcoming Jupiter system missions. Here, we provide expectations for Juno, which is scheduled to arrive at Jupiter in July 2016. Accounting for the long-term decline in solar wind dynamic pressure reported by McComas et al. (2013a), Jupiter's bow shock and magnetopause is expected to be at least 8–12% further from Jupiter, if these trends continue.

Were chondrites magnetized by the early solar wind?

Science.gov (United States)

Oran, Rona; Weiss, Benjamin P.; Cohen, Ofer

2018-06-01

Chondritic meteorites have been traditionally thought to be samples of undifferentiated bodies that never experienced large-scale melting. This view has been challenged by the existence of post-accretional, unidirectional natural remanent magnetization (NRM) in CV carbonaceous chondrites. The relatively young inferred NRM age [∼10 million years (My) after solar system formation] and long duration of NRM acquisition (1-106 y) have been interpreted as evidence that the magnetizing field was that of a core dynamo within the CV parent body. This would imply that CV chondrites represent the primitive crust of a partially differentiated body. However, an alternative hypothesis is that the NRM was imparted by the early solar wind. Here we demonstrate that the solar wind scenario is unlikely due to three main factors: 1) the magnitude of the early solar wind magnetic field is estimated to be limits field amplification due to pile-up of the solar wind to less than a factor of 3.5 times that of the instantaneous solar wind field, and 3) the solar wind field likely changed over timescales orders of magnitude shorter than the timescale of NRM acquisition. Using analytical arguments, numerical simulations and astronomical observations of the present-day solar wind and magnetic fields of young stars, we show that the maximum mean field the ancient solar wind could have imparted on an undifferentiated CV parent body is <3.5 nT, which is 3-4 and 3 orders of magnitude weaker than the paleointensities recorded by the CV chondrites Allende and Kaba, respectively. Therefore, the solar wind is highly unlikely to be the source of the NRM in CV chondrites. Nevertheless, future high sensitivity paleomagnetic studies of rapidly-cooled meteorites with high magnetic recording fidelity could potentially trace the evolution of the solar wind field in time.

Spectroscopic Measurements of the Ion Velocity Distribution at the Base of the Fast Solar Wind

Science.gov (United States)

Jeffrey, Natasha L. S.; Hahn, Michael; Savin, Daniel W.; Fletcher, Lyndsay

2018-03-01

In situ measurements of the fast solar wind reveal non-thermal distributions of electrons, protons, and minor ions extending from 0.3 au to the heliopause. The physical mechanisms responsible for these non-thermal properties and the location where these properties originate remain open questions. Here, we present spectroscopic evidence, from extreme ultraviolet spectroscopy, that the velocity distribution functions (VDFs) of minor ions are already non-Gaussian at the base of the fast solar wind in a coronal hole, at altitudes of thermal equilibrium, (b) fluid motions such as non-Gaussian turbulent fluctuations or non-uniform wave motions, or (c) some combination of both. These observations provide important empirical constraints for the source region of the fast solar wind and for the theoretical models of the different acceleration, heating, and energy deposition processes therein. To the best of our knowledge, this is the first time that the ion VDF in the fast solar wind has been probed so close to its source region. The findings are also a timely precursor to the upcoming 2018 launch of the Parker Solar Probe, which will provide the closest in situ measurements of the solar wind at approximately 0.04 au (8.5 solar radii).

Transient behavior of a flare-associated solar wind. I - Gas dynamics in a radial open field region

Science.gov (United States)

Nagai, F.

1984-01-01

A numerical investigation is conducted into the way in which a solar wind model initially satisfying both steady state and energy balance conditions is disturbed and deformed, under the assumption of heating that correspoonds to the energy release of solar flares of an importance value of approximately 1 which occur in radial open field regions. Flare-associated solar wind transient behavior is modeled for 1-8 solar radii. The coronal temperature around the heat source region rises, and a large thermal conductive flux flows inward to the chromosphere and outward to interplanetary space along field lines. The speed of the front of expanding chromospheric material generated by the impingement of the conduction front on the upper chromosphere exceeds the local sound velocity in a few minutes and eventually exceeds 100 million cm/sec.

On the Origins of the Intercorrelations Between Solar Wind Variables

Science.gov (United States)

Borovsky, Joseph E.

2018-01-01

It is well known that the time variations of the diverse solar wind variables at 1 AU (e.g., solar wind speed, density, proton temperature, electron temperature, magnetic field strength, specific entropy, heavy-ion charge-state densities, and electron strahl intensity) are highly intercorrelated with each other. In correlation studies of the driving of the Earth's magnetosphere-ionosphere-thermosphere system by the solar wind, these solar wind intercorrelations make determining cause and effect very difficult. In this report analyses of solar wind spacecraft measurements and compressible-fluid computer simulations are used to study the origins of the solar wind intercorrelations. Two causes are found: (1) synchronized changes in the values of the solar wind variables as the plasma types of the solar wind are switched by solar rotation and (2) dynamic interactions (compressions and rarefactions) in the solar wind between the Sun and the Earth. These findings provide an incremental increase in the understanding of how the Sun-Earth system operates.

Coherent structures at ion scales in fast and slow solar wind: Cluster observations

Science.gov (United States)

Perrone, D.; Alexandrova, O.; Zouganelis, Y.; Roberts, O.; Lion, S.; Escoubet, C. P.; Walsh, A. P.; Maksimovic, M.; Lacombe, C.

2017-12-01

Spacecraft measurements generally reveal that solar wind electromagnetic fluctuations are in a state of fully-developed turbulence. Turbulence represents a very complex problem in plasmas since cross-scale coupling and kinetic effects are present. Moreover, the intermittency phenomenon, i.e. the manifestation of the non-uniform and inhomogeneous energy transfer and dissipation in a turbulent system, represents a very important aspect of the solar wind turbulent cascade. Here, we study coherent structures responsible for solar wind intermittency around ion characteristic scales. We find that, in fast solar wind, intermittency is due to Alfvén vortex-like structures and current sheets. In slow solar wind, we observe as well compressive structures like magnetic solitons, holes and shocks. By using high-time resolution magnetic field data of multi-point measurements of Cluster spacecraft, we characterize the observed coherent structures in terms of topology and propagation speed. We show that all structures around ion characteristic scales, both in fast and slow solar wind, are characterized by a strong wave-vector anisotropy in the perpendicular direction with respect to the local magnetic field. Moreover, some of them propagate in the plasma rest frame in the direction perpendicular to the local field. Finally, a further analysis on the electron and ion velocity distributions shows a high variability; in particular, close to coherent structures the electron and ion distribution functions appear strongly deformed and far from the thermodynamic equilibrium. Possible interpretations of the observed structures and their role in the heating process of the plasma are also discussed.

A survey of solar wind conditions at 5 AU: A tool for interpreting solar wind-magnetosphere interactions at Jupiter

Directory of Open Access Journals (Sweden)

Robert Wilkes Ebert

2014-09-01

Full Text Available We examine Ulysses solar wind and interplanetary magnetic field (IMF observations at 5 AU for two ~13 month intervals during the rising and declining phases of solar cycle 23 and the predicted response of the Jovian magnetosphere during these times. The declining phase solar wind, composed primarily of corotating interaction regions and high-speed streams, was, on average, faster, hotter, less dense, and more Alfvénic relative to the rising phase solar wind, composed mainly of slow wind and interplanetary coronal mass ejections. Interestingly, none of solar wind and IMF distributions reported here were bimodal, a feature used to explain the bimodal distribution of bow shock and magnetopause standoff distances observed at Jupiter. Instead, many of these distributions had extended, non-Gaussian tails that resulted in large standard deviations and much larger mean over median values. The distribution of predicted Jupiter bow shock and magnetopause standoff distances during these intervals were also not bimodal, the mean/median values being larger during the declining phase by ~1 – 4%. These results provide data-derived solar wind and IMF boundary conditions at 5 AU for models aimed at studying solar wind-magnetosphere interactions at Jupiter and can support the science investigations of upcoming Jupiter system missions. Here, we provide expectations for Juno, which is scheduled to arrive at Jupiter in July 2016. Accounting for the long-term decline in solar wind dynamic pressure reported by McComas et al. (2013, Jupiter’s bow shock and magnetopause is expected to be at least 8 – 12% further from Jupiter, if these trends continue.

Distribution and solar wind control of compressional solar wind-magnetic anomaly interactions observed at the Moon by ARTEMIS

Science.gov (United States)

Halekas, J. S.; Poppe, A. R.; Lue, C.; Farrell, W. M.; McFadden, J. P.

2017-06-01

A statistical investigation of 5 years of observations from the two-probe Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) mission reveals that strong compressional interactions occur infrequently at high altitudes near the ecliptic but can form in a wide range of solar wind conditions and can occur up to two lunar radii downstream from the lunar limb. The compressional events, some of which may represent small-scale collisionless shocks ("limb shocks"), occur in both steady and variable interplanetary magnetic field (IMF) conditions, with those forming in steady IMF well organized by the location of lunar remanent crustal magnetization. The events observed by ARTEMIS have similarities to ion foreshock phenomena, and those observed in variable IMF conditions may result from either local lunar interactions or distant terrestrial foreshock interactions. Observed velocity deflections associated with compressional events are always outward from the lunar wake, regardless of location and solar wind conditions. However, events for which the observed velocity deflection is parallel to the upstream motional electric field form in distinctly different solar wind conditions and locations than events with antiparallel deflections. Consideration of the momentum transfer between incoming and reflected solar wind populations helps explain the observed characteristics of the different groups of events.Plain Language SummaryWe survey the environment around the Moon to determine when and where strong amplifications in the charged particle density and magnetic field strength occur. These structures may be some of the smallest shock waves in the solar system, and learning about their formation informs us about the interaction of charged particles with small-scale magnetic fields throughout the solar system and beyond. We find that these compressions occur in an extended region downstream from the lunar dawn and dusk regions and

Physics-based Tests to Identify the Accuracy of Solar Wind Ion Measurements: A Case Study with the Wind Faraday Cups

Science.gov (United States)

Kasper, J. C.; Lazarus, A. J.; Steinberg, J. T.; Ogilvie, K. W.; Szabo, A.

2006-01-01

We present techniques for comparing measurements of velocity, temperature, and density with constraints imposed by the plasma physics of magnetized bi-Maxwellian ions. Deviations from these physics-based constraints are interpreted as arising from measurement errors. Two million ion spectra from the Solar Wind Experiment Faraday Cup instruments on the Wind spacecraft are used as a case study. The accuracy of velocity measurements is determined by the fact that differential flow between hydrogen and helium should be aligned with the ambient magnetic field. Modeling the breakdown of field alignment suggests velocity uncertainties are less than 0.16% in magnitude and 3deg in direction. Temperature uncertainty is found by examining the distribution of observed temperature anisotropies in high-beta solar wind intervals where the firehose, mirror, and cyclotron microinstabilities should drive the distribution to isotropy. The presence of a finite anisotropy at high beta suggests overall temperature uncertainties of 8%. Hydrogen and helium number densities are compared with the electron density inferred from observations of the local electron plasma frequency as a function of solar wind speed and year. We find that after accounting for the contribution of minor ions, the results are consistent with a systematic offset between the two instruments of 34%. The temperature and density methods are sensitive to non-Maxwellian features such as heat flux and proton beams and as a result are more suited to slow solar wind where these features are rare. These procedures are of general use in identifying the accuracy of observations from any solar wind ion instrument.

Is tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control?

Science.gov (United States)

Prikryl, Paul; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Bruntz, Robert; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel; Pastirčák, Vladimír

2017-04-01

More than four decades have passed since a link between solar wind magnetic sector boundary structure and mid-latitude upper tropospheric vorticity was discovered (Wilcox et al., Science, 180, 185-186, 1973). The link has been later confirmed and various physical mechanisms proposed but apart from controversy, little attention has been drawn to these results. To further emphasize their importance we investigate the occurrence of mid-latitude severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system. It is observed that significant snowstorms, windstorms and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., Ann. Geophys., 27, 1-30, 2009; Prikryl et al., J. Atmos. Sol.-Terr. Phys., 149, 219-231, 2016) is corroborated for the southern hemisphere. A physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., Space Sci. Rev., 54, 297-375, 1990) show that propagating waves originating in the thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere thus initiating convection to form cloud/precipitation bands

Performance of a solar augmented heat pump

Science.gov (United States)

Bedinger, A. F. G.; Tomlinson, J. J.; Reid, R. L.; Chaffin, D. J.

Performance of a residential size solar augmented heat pump is reported for the 1979-1980 heating season. The facility located in Knoxville, Tennessee, has a measured heat load coefficient of 339.5 watt/C (644 BTU/hr- F). The solar augmented heat pump system consists of 7.4 cu m of one inch diameter crushed limestone. The heat pump is a nominal 8.8 KW (2 1/2 ton) high efficiency unit. The system includes electric resistance heaters to give the option of adding thermal energy to the pebble bed storage during utility off-peak periods, thus offering considerable load management capability. A 15 KW electric resistance duct heater is used to add thermal energy to the pebble bin as required during off-peak periods. Hourly thermal performance and on site weather data was taken for the period November 1, 1979, to April 13, 1980. Thermal performance data consists of heat flow summations for all modes of the system, pebble bed temperatures, and space temperature. Weather data consists of dry bulb temperature, dew point temperature, total global insolation (in the plane of the collector), and wind speed and direction. An error analysis was performed and the least accurate of the measurements was determined to be the heat flow at 5%. Solar system thermal performance factor was measured to be 8.77. The heat pump thermal performance factor was 1.64. Total system seasonal performance factor was measured to be 1.66. Using a modified version of TRNSYS, the thermal performance of this system was simulated. When simulation results were compared with data collected onsite, the predicted heat flow and power consumption generally were within experimental accuracy.

Limitation of solar energy and wind energy

International Nuclear Information System (INIS)

White, R. S.

2008-01-01

Wind turbines, solar energy collectors and photovoltaic cells have been popular sources of electricity since the oil crisis in the late seventies, and they are increasingly favored by many scientists and much of the public as methods for reducing global warming. The older wind farms in California are outdated. New wind turbines have not followed, primarily because of competition from lower-cost natural gas. The Times urges increased federal and state subsidies for the wind and solar industries. The primary reason that wind and solar energies have not made inroads in the past, and will never supply more than a few percentage points of the world's electrical energy, is their unpredictable variations in time and their constant need for back-ups. The only non-carbon-dioxide-emitting generator capable of backing up wind and solar energy and replacing coal and gas generators is nuclear fission. Nuclear power may be the practical solution to global warming, after all.

Large-scale solar heating

Energy Technology Data Exchange (ETDEWEB)

Tolonen, J.; Konttinen, P.; Lund, P. [Helsinki Univ. of Technology, Otaniemi (Finland). Advanced Energy Systems

1998-10-01

Solar heating market is growing in many European countries and annually installed collector area has exceeded one million square meters. There are dozens of collector manufacturers and hundreds of firms making solar heating installations in Europe. One tendency in solar heating is towards larger systems. These can be roof integrated, consisting of some tens or hundreds of square meters of collectors, or they can be larger centralized solar district heating plants consisting of a few thousand square meters of collectors. The increase of size can reduce the specific investments of solar heating systems, because e.g. the costs of some components (controllers, pumps, and pipes), planning and installation can be smaller in larger systems. The solar heat output can also be higher in large systems, because more advanced technique is economically viable

Study on Pyroelectric Harvesters Integrating Solar Radiation with Wind Power

Directory of Open Access Journals (Sweden)

Chun-Ching Hsiao

2015-07-01

Full Text Available Pyroelectric harvesters use temperature fluctuations to generate electrical outputs. Solar radiation and waste heat are rich energy sources that can be harvested. Pyroelectric energy converters offer a novel and direct energy-conversion technology by transforming time-dependent temperatures directly into electricity. Moreover, the great challenge for pyroelectric energy harvesting lies in finding promising temperature variations or an alternating thermal loading in real situations. Hence, in this article, a novel pyroelectric harvester integrating solar radiation with wind power by the pyroelectric effect is proposed. Solar radiation is a thermal source, and wind is a dynamic potential. A disk generator is used for harvesting wind power. A mechanism is considered to convert the rotary energy of the disk generator to drive a shutter for generating temperature variations in pyroelectric cells using a planetary gear system. The optimal period of the pyroelectric cells is 35 s to harvest the stored energy, about 70 μJ, while the rotary velocity of the disk generator is about 31 RPM and the wind speed is about 1 m/s. In this state, the stored energy acquired from the pyroelectric harvester is about 75% more than that from the disk generator. Although the generated energy of the proposed pyroelectric harvester is less than that of the disk generator, the pyroelectric harvester plays a complementary role when the disk generator is inactive in situations of low wind speed.

Solar energy system with wind vane

Science.gov (United States)

Grip, Robert E

2015-11-03

A solar energy system including a pedestal defining a longitudinal axis, a frame that is supported by the pedestal and that is rotateable relative to the pedestal about the longitudinal axis, the frame including at least one solar device, and a wind vane operatively connected to the frame to urge the frame relative to the pedestal about the longitudinal axis in response to wind acting on the wind vane.

A desalination plant with solar and wind energy

International Nuclear Information System (INIS)

Chen, H; Ye, Z; Gao, W

2013-01-01

The shortage of freshwater resources has become a worldwide problem. China has a water shortage, although the total amount of water resources is the sixth in the world, the per capita water capacity is the 121th (a quarter of the world's per capita water capacity), and the United Nations considers China one of the poorest 13 countries in the world in terms of water. In order to increase the supply of fresh water, a realistic way is to make full use of China's long and narrow coastline for seawater desalination. This paper discusses a sea water desalination device, the device adopts distillation, uses the greenhouse effect principle and wind power heating principle, and the two-type start is used to solve the problem of vertical axis wind turbine self-starting. Thrust bearings are used to ensure the stability of the device, and to ensure absorbtion of wind energy and solar energy, and to collect evaporation of water to achieve desalination. The device can absorb solar and wind energy instead of input energy, so it can be used in ship, island and many kinds of environment. Due to the comprehensive utilization of wind power and solar power, the efficiency of the device is more than other passive sea water desalting plants, the initial investment and maintenance cost is lower than active sea water desalting plant. The main part of the device cannot only be used in offshore work, but can also be used in deep sea floating work, so the device can utilise deep sea energy. In order to prove the practicability of the device, the author has carried out theory of water production calculations. According to the principle of conservation of energy, the device ais bsorbing solar and wind power, except loose lost part which is used for water temperature rise and phase transition. Assume the inflow water temperature is 20 °C, outflow water temperature is 70 °C, the energy utilization is 60%, we can know that the water production quantity is 8 kg/ m 2 per hour. Comparing

Solar Heating System with Building-Integrated Heat Storage

DEFF Research Database (Denmark)

Heller, Alfred

1996-01-01

Traditional solar heating systems cover between 5 and 10% of the heat demand fordomestic hot water and comfort heating. By applying storage capacity this share can beincreased much. The Danish producer of solar heating systems, Aidt-Miljø, markets such a system including storage of dry sand heated...... by PP-pipe heat exchanger. Heat demand is reduced due to direct solar heating, and due to storage. Heat demand is reduced due to direct solar heating, due to storage and due to lower heat losses through the ground. In theory, by running the system flow backwards through the sand storage, active heating...... can be achieved.The objective of the report is to present results from measured system evaluation andcalculations and to give guidelines for the design of such solar heating systems with building integrated sand storage. The report is aimed to non-technicians. In another report R-006 the main results...

Heat loss investigation from spherical cavity receiver of solar concentrator

Energy Technology Data Exchange (ETDEWEB)

Shewale, V. C. [Dept. of Mechanical Engineering, NDMVPS KBT College of Engineering, Nashik (India); Dongarwar, P. R. [Dept. of Mechanical Engineering, College of Military Engineering, Pune (India); Gawande, R. P. [Dept. of Mechanical Engineering, B.D.C.O.E. Wardha, Nagpur University, NagpurI (India)

2016-11-15

The heat losses are mainly affects on the performance of cavity receiver of solar concentrator. In this paper, the experimental and numerical study is carried out for different heat losses from spherical cavity receiver of 0.385 m cavity diameter and 0.154 m opening diameter. The total and convection losses are studied experimentally to no wind and wind conditions for the temperature range of 150 °C to 300 °C at 0°, 30°, 45°, 60° and 90° inclination angle of cavity receiver. The experimental set up mainly consists of copper tube material cavity receiver wrapped with nichrome heating coil to heat the cavity and insulated with glasswool insulation. The numerical analysis was carried out with Fluent Computational fluid dynamics (CFD) software, to study connective heat losses for no wind condition only. The numerical results are compared with experimental results and found good agreement with maximum deviation of 12 %. The effect of inclination angle of cavity receiver on total losses and convection losses shows that as the inclination angle increases from 0o to 90o, both losses decreased due to decreased in convective zone into the cavity receiver. The effect of operating temperature of cavity shows that as the temperature of cavity receiver increases, the total and convective losses goes on increasing. The effect of external wind at 2 m/s and 4 m/s in two directions (side-on wind and head-on wind) is also studied experimentally for total and convective heat losses. The result shows that the heat losses are higher for head-on wind condition compared to side-on wind and no wind condition at all inclination angle of cavity receiver. The present results are also compared to the convective losses obtained from the correlations of Stine and Mcdonald and M. Prakash. The convective loss from these correlations shows nearest prediction to both experimental and numerical results.

Heat loss investigation from spherical cavity receiver of solar concentrator

International Nuclear Information System (INIS)

Shewale, V. C.; Dongarwar, P. R.; Gawande, R. P.

2016-01-01

The heat losses are mainly affects on the performance of cavity receiver of solar concentrator. In this paper, the experimental and numerical study is carried out for different heat losses from spherical cavity receiver of 0.385 m cavity diameter and 0.154 m opening diameter. The total and convection losses are studied experimentally to no wind and wind conditions for the temperature range of 150 °C to 300 °C at 0°, 30°, 45°, 60° and 90° inclination angle of cavity receiver. The experimental set up mainly consists of copper tube material cavity receiver wrapped with nichrome heating coil to heat the cavity and insulated with glasswool insulation. The numerical analysis was carried out with Fluent Computational fluid dynamics (CFD) software, to study connective heat losses for no wind condition only. The numerical results are compared with experimental results and found good agreement with maximum deviation of 12 %. The effect of inclination angle of cavity receiver on total losses and convection losses shows that as the inclination angle increases from 0o to 90o, both losses decreased due to decreased in convective zone into the cavity receiver. The effect of operating temperature of cavity shows that as the temperature of cavity receiver increases, the total and convective losses goes on increasing. The effect of external wind at 2 m/s and 4 m/s in two directions (side-on wind and head-on wind) is also studied experimentally for total and convective heat losses. The result shows that the heat losses are higher for head-on wind condition compared to side-on wind and no wind condition at all inclination angle of cavity receiver. The present results are also compared to the convective losses obtained from the correlations of Stine and Mcdonald and M. Prakash. The convective loss from these correlations shows nearest prediction to both experimental and numerical results

EXPERIMENTAL DETERMINATION OF WHISTLER WAVE DISPERSION RELATION IN THE SOLAR WIND

Energy Technology Data Exchange (ETDEWEB)

Stansby, D.; Horbury, T. S.; Chen, C. H. K.; Matteini, L., E-mail: david.stansby14@imperial.ac.uk [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom)

2016-09-20

The origins and properties of large-amplitude whistler wavepackets in the solar wind are still unclear. In this Letter, we utilize single spacecraft electric and magnetic field waveform measurements from the ARTEMIS mission to calculate the plasma frame frequency and wavevector of individual wavepackets over multiple intervals. This allows direct comparison of experimental measurements with theoretical dispersion relations to identify the observed waves as whistler waves. The whistlers are right-hand circularly polarized, travel anti-sunward, and are aligned with the background magnetic field. Their dispersion is strongly affected by the local electron parallel beta in agreement with linear theory. The properties measured are consistent with the electron heat flux instability acting in the solar wind to generate these waves.

Solar heating cooling. Preparation of possible participation in IEA, Solar Heating Cooling Task 25

International Nuclear Information System (INIS)

2001-03-01

For the Danish solar heating industries it is interesting to discuss the domestic market possibilities and the export possibilities for solar heating cooling systems. The Danish solar heating sector also wants to participate in the international collaboration within IEA Solar Heating and Cooling Task 25 'Solar Assisted Air Conditioning of Buildings'. The Danish Energy Agency therefore has granted means for this project to discuss: The price of cooling for 3 different solar cooling methods (absorption cooling, desiccant cooling and ejector cooling); Market possibilities in Denmark and abroad; The advantages by Danish participation in IEA Task 25. The task has been solved through literature studies to establish status for the 3 technologies. It turned out that ejector cooling by low temperatures (85 deg. C from the solar collector) exists as pilot plants in relation to district heating, but is still not commercial accessible. Desiccant cooling, where the supplied heat has temperatures down to 55 deg. C is a well-developed technology. However only a handful of pilot plants with solar heating exists, and thus optimization relating to operation strategy and economy is on the experimental stage. Absorption cooling plants driven by solar heating are found in a large number in Japan and are also demonstrated in several other countries. The combination of absorption heating pump and solar heating is considered to be commercial accessible. Solar heating is interesting as heat source of to the extent that it can replace other sources of heat without the economy being depreciated. This can be the case in South Europe if: 1) oil or natural gas is used for heating; 2) a solar heating system already exists, e.g. for domestic water supply, and is installed so that the marginal costs by solar heating supply of the ventilation plant is reduced. All in all the above conditions mean that the market for solar heating for cooling is very limited in Europe, where almost everybody are

Solar Illumination Control of the Polar Wind

Science.gov (United States)

Maes, L.; Maggiolo, R.; De Keyser, J.; André, M.; Eriksson, A. I.; Haaland, S.; Li, K.; Poedts, S.

2017-11-01

Polar wind outflow is an important process through which the ionosphere supplies plasma to the magnetosphere. The main source of energy driving the polar wind is solar illumination of the ionosphere. As a result, many studies have found a relation between polar wind flux densities and solar EUV intensity, but less is known about their relation to the solar zenith angle at the ionospheric origin, certainly at higher altitudes. The low energy of the outflowing particles and spacecraft charging means it is very difficult to measure the polar wind at high altitudes. We take advantage of an alternative method that allows estimations of the polar wind flux densities far in the lobes. We analyze measurements made by the Cluster spacecraft at altitudes from 4 up to 20 RE. We observe a strong dependence on the solar zenith angle in the ion flux density and see that both the ion velocity and density exhibit a solar zenith angle dependence as well. We also find a seasonal variation of the flux density.

Primitive Terrestrial Xenon: A Relation to Refined Composition of Solar Wind

OpenAIRE

Meshik, A.; Pravdivtseva, O.; Burnett, D.; Hohenberg, C.

2015-01-01

To explain the isotopic structure of terrestrial Xe, a hypothetical U-Xe (unrelated to uranium) was mathematically constructed using multidimensional correlation diagrams of stepwise heating data of carbonaceous chondrites [1]. The composition of U-Xe was derived without any references to solar Xe. Nevertheless U-Xe turned out to be almost identical to Solar Wind (SW) except for two heaviest isotopes ^(136)Xe and ^(134)Xe, in which U-Xe was depleted. The mismatch in these two heaviest Xe isot...

WIND observations of coherent electrostatic waves in the solar wind

Directory of Open Access Journals (Sweden)

A. Mangeney

1999-03-01

Full Text Available The time domain sampler (TDS experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near the Lagrange point L1. In the range of frequencies above the proton plasma frequency fpi and smaller than or of the order of the electron plasma frequency fpe, TDS observed three kinds of electrostatic (e.s. waves: coherent wave packets of Langmuir waves with frequencies f ~ fpe, coherent wave packets with frequencies in the ion acoustic range fpi < f < fpe, and more or less isolated non-sinusoidal spikes lasting less than 1 ms. We confirm that the observed frequency of the low frequency (LF ion acoustic wave packets is dominated by the Doppler effect: the wavelengths are short, 10 to 50 electron Debye lengths λD. The electric field in the isolated electrostatic structures (IES and in the LF wave packets is more or less aligned with the solar wind magnetic field. Across the IES, which have a spatial width of the order of ~ 25λD, there is a small but finite electric potential drop, implying an average electric field generally directed away from the Sun. The IES wave forms, which have not been previously reported in the solar wind, are similar, although with a smaller amplitude, to the weak double layers observed in the auroral regions, and to the electrostatic solitary waves observed in other regions in the magnetosphere. We have also studied the solar wind conditions which favour the occurrence of the three kinds of waves: all these e.s. waves are observed more or less continuously in the whole solar wind (except in the densest regions where a parasite prevents the TDS observations. The type (wave packet or IES of the observed LF waves is mainly determined by the proton temperature and by the direction of the magnetic field, which themselves depend on the latitude of WIND with respect to the heliospheric current sheet.Key words

Solar/electric heating systems for the future energy system

Energy Technology Data Exchange (ETDEWEB)

Furbo, S.; Dannemand, M.; Perers, B. [and others

2013-05-15

The aim of the project is to elucidate how individual heating units for single family houses are best designed in order to fit into the future energy system. The units are based on solar energy, electrical heating elements/heat pump, advanced heat storage tanks and advanced control systems. Heat is produced by solar collectors in sunny periods and by electrical heating elements/heat pump. The electrical heating elements/heat pump will be in operation in periods where the heat demand cannot be covered by solar energy. The aim is to use the auxiliary heating units when the electricity price is low, e.g. due to large electricity production by wind turbines. The unit is equipped with an advanced control system where the control of the auxiliary heating is based on forecasts of the electricity price, the heat demand and the solar energy production. Consequently, the control is based on weather forecasts. Three differently designed heating units are tested in a laboratory test facility. The systems are compared on the basis of: 1) energy consumption for the auxiliary heating; 2) energy cost for the auxiliary heating; 3) net utilized solar energy. Starting from a normal house a solar combi system (for hot water and house heating) can save 20-30% energy cost, alone, depending on sizing of collector area and storage volume. By replacing the heat storage with a smart tank based on electric heating elements and a smart control based on weather/load forecast and electricity price information 24 hours ahead, another 30-40% can be saved. That is: A solar heating system with a solar collector area of about 10 m{sup 2}, a smart tank based on electric heating element and a smart control system, can reduce the energy costs of the house by at least 50%. No increase of heat storage volume is needed to utilize the smart control. The savings in % are similar for different levels of building insulation. As expected a heat pump in the system can further reduce the auxiliary electricity

Solar wind ion trends and signatures: STEREO PLASTIC observations approaching solar minimum

Directory of Open Access Journals (Sweden)

A. B. Galvin

2009-10-01

Full Text Available STEREO has now completed the first two years of its mission, moving from close proximity to Earth in 2006/2007 to more than 50 degrees longitudinal separation from Earth in 2009. During this time, several large-scale structures have been observed in situ. Given the prevailing solar minimum conditions, these structures have been predominantly coronal hole-associated solar wind, slow solar wind, their interfaces, and the occasional transient event. In this paper, we extend earlier solar wind composition studies into the current solar minimum using high-resolution (1-h sampling times for the charge state analysis. We examine 2-year trends for iron charge states and solar wind proton speeds, and present a case study of Carrington Rotation 2064 (December 2007 which includes minor ion (He, Fe, O kinetic and Fe composition parameters in comparison with proton and magnetic field signatures at large-scale structures observed during this interval.

Estimates of the price of hydrogen as a medium for wind and solar sources

International Nuclear Information System (INIS)

Bockris, John O'M.; Veziroglu, T. Nejat

2007-01-01

The rejection of hydrogen as a solution to global warming by becoming the medium of wind and solar was made when gasoline was priced at $1/gallon. From wind, H 2 would now cost (by electrolysis of water and steam) less than $3 for an amount equivalent in energy to that in a gallon of gasoline ('equivalent'). From solar photovoltaics (pv), H 2 would be sinking in price between $8 toward $5 equivalent as the efficiency of solar pv increases toward 20%. Solar thermal's present prices offer about one-half the solar pv prices. Prediction of the maximum of the delivery rate of world oil is [Laherre's Oil Production Forecast, 1950-2150. Reprinted with permission from correspondence with William Horvath, U.S. Department of Energy, March 29, 2001] 2010. Future energy sources will develop inexhaustible energies from wind, solar, geothermal, tidal, and wave sources. The common media will be hydrogen and electricity. These sources yield energy at around one-half the cost of nuclear fission. Growing corn to make alcohol involves a net loss of energy and need for a heating mechanism. It may increase the Greenhouse. (author)

Solar heat storages in district heating networks

Energy Technology Data Exchange (ETDEWEB)

Ellehauge, K. (Ellehauge og Kildemoes, AArhus (DK)); Engberg Pedersen, T. (COWI A/S, Kgs. Lyngby (DK))

2007-07-15

This report gives information on the work carried out and the results obtained in Denmark on storages for large solar heating plants in district heating networks. Especially in Denmark the share of district heating has increased to a large percentage. In 1981 around 33% of all dwellings in DK were connected to a district heating network, while the percentage in 2006 was about 60% (in total 1.5 mio. dwellings). In the report storage types for short term storage and long term storages are described. Short term storages are done as steel tanks and is well established technology widely used in district heating networks. Long term storages are experimental and used in connection with solar heating. A number of solar heating plants have been established with either short term or long term storages showing economy competitive with normal energy sources. Since, in the majority of the Danish district heating networks the heat is produced in co-generation plants, i.e. plants producing both electricity and heat for the network, special attention has been put on the use of solar energy in combination with co-generation. Part of this report describes that in the liberalized electricity market central solar heating plants can also be advantageous in combination with co-generation plants. (au)

Solar wind control of stratospheric temperatures in Jupiter's auroral regions?

Science.gov (United States)

Sinclair, James Andrew; Orton, Glenn; Kasaba, Yasumasa; Sato, Takao M.; Tao, Chihiro; Waite, J. Hunter; Cravens, Thomas; Houston, Stephen; Fletcher, Leigh; Irwin, Patrick; Greathouse, Thomas K.

2017-10-01

Auroral emissions are the process through which the interaction of a planet’s atmosphere and its external magnetosphere can be studied. Jupiter exhibits auroral emission at a multitude of wavelengths including the X-ray, ultraviolet and near-infrared. Enhanced emission of CH4 and other stratospheric hydrocarbons is also observed coincident with Jupiter’s shorter-wavelength auroral emission (e.g. Caldwell et al., 1980, Icarus 44, 667-675, Kostiuk et al., 1993, JGR 98, 18823). This indicates that auroral processes modify the thermal structure and composition of the auroral stratosphere. The exact mechanism responsible for this auroral-related heating of the stratosphere has however remained elusive (Sinclair et al., 2017a, Icarus 292, 182-207, Sinclair et al., 2017b, GRL, 44, 5345-5354). We will present an analysis of 7.8-μm images of Jupiter measured by COMICS (Cooled Mid-Infrared Camera and Spectrograph, Kataza et al., 2000, Proc. SPIE(4008), 1144-1152) on the Subaru telescope. These images were acquired on January 11th, 12th, 13th, 14th, February 4, 5th and May 17th, 18th, 19th and 20th in 2017, allowing the daily variability of Jupiter’s auroral-related stratospheric heating to be tracked. Preliminary results suggest lower stratospheric temperatures are directly forced by the solar wind dynamical pressure. The southern auroral hotspot exhibited a significant increase in brightness temperature over a 24-hour period. Over the same time period, a solar wind propagation model (Tao et al. 2005, JGR 110, A11208) predicts a strong increase in the solar wind dynamical pressure at Jupiter.

Elemental composition and ionization state of the solar atmosphere and solar wind

International Nuclear Information System (INIS)

Joselyn, J.A.C.

1978-01-01

Abundance measurements have always proved useful in generating and refining astrophysical theories. Some of the classical problems of astrophysics involve determining the relative abundances of elements in the atmosphere of a star from observations of its line spectrum, and then synthesizing the physical processes which would produce such abundances. Theories of the formation of the solar system are critically tested by their ability to explain observed abundances, and, elemental abundances can serve as tracers, helping to determine the origin and transport of ions. Since the solar wind originates at the sun, it can act as a diagnostic probe of solar conditions. In particular, measurements of the composition of the solar wind should be related to the solar composition. And, assuming ionization equilibrium, measurements of the relative abundances of the ionization states in the solar wind should infer coronal temperatures and temperature gradients. However, most spherically symmetric models of the solar wind are unable to explain the relationship between the composition estimated from solar observations and as measured at 1 AU; and, recent observations of significant flow speeds in the transition region raise doubts about the validity of the assumption of ionization equilibrium

Solar-wind interactions with the Moon: role of oxygen ions

International Nuclear Information System (INIS)

Mukherjee, N.R.

1979-01-01

The solar-wind interacts directly with the lunar surface due to tenuous atmosphere and magnetic field. The interaction results in an almost complete absorption of the solar-wind corpuscles producing no upstream bowshock but a cavity downstream. The solar-wind oxygen ionic species induce and undergo a complex set of reactions with the elements of the lunar minerals and the solar-wind derived trapped gases. In this paper, the long-term concentration and the role of oxygen derived from the solar-wind is discussed. (Auth.)

Laboratory Facility for Simulating Solar Wind Sails

International Nuclear Information System (INIS)

Funaki, Ikkoh; Ueno, Kazuma; Oshio, Yuya; Ayabe, Tomohiro; Horisawa, Hideyuki; Yamakawa, Hiroshi

2008-01-01

Magnetic sail (MagSail) is a deep space propulsion system, in which an artificial magnetic cavity captures the energy of the solar wind to propel a spacecraft in the direction leaving the sun. For a scale-model experiment of the plasma flow of MagSail, we employed a magnetoplasmadynamic arcjet as a solar wind simulator. It is observed that a plasma flow from the solar wind simulator reaches a quasi-steady state of about 0.8 ms duration after a transient phase when initiating the discharge. During this initial phase of the discharge, a blast-wave was observed to develop radially in a vacuum chamber. When a solenoidal coil (MagSail scale model) is immersed into the quasi-steady flow where the velocity is 45 km/s, and the number density is 10 19 m-3, a bow shock as well as a magnetic cavity were formed in front of the coil. As a result of the interaction between the plasma flow and the magnetic cavity, the momentum of the simulated solar wind is decreased, and it is found from the thrust measurement that the solar wind momentum is transferred to the coil simulating MagSail.

Solar wind temperature observations in the outer heliosphere

Science.gov (United States)

Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J.

1992-01-01

The Pioneer 10, Pioneer 11, and Voyager 2 spacecraft are now at heliocentric distances of 50, 32 and 33 AU, and heliographic latitudes of 3.5 deg N, 17 deg N, and 0 deg N, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer l0 is on the opposite side of the sun. The baselines defined by these spacecraft make it possible to resolve radial, longitudinal, and latitudinal variations of solar wind parameters. The solar wind temperature decreases with increasing heliocentric distance out to a distance of 10-15 AU. At larger heliocentric distances, this gradient disappears. These high solar wind temperatures in the outer heliosphere have persisted for at least 10 years, which suggests that they are not a solar cycle effect. The solar wind temperature varied with heliographic latitude during the most recent solar minimum. The solar wind temperature at Pioneer 11 and Voyager 2 was higher than that seen at Pioneer 10 for an extended period of time, which suggests the existence of a large-scale variation of temperature with celestial longitude, but the contribution of transient phenomena is yet to be clarified.

A Generalized Equatorial Model for the Accelerating Solar Wind

Science.gov (United States)

Tasnim, S.; Cairns, Iver H.; Wheatland, M. S.

2018-02-01

A new theoretical model for the solar wind is developed that includes the wind's acceleration, conservation of angular momentum, deviations from corotation, and nonradial velocity and magnetic field components from an inner boundary (corresponding to the onset of the solar wind) to beyond 1 AU. The model uses a solution of the time-steady isothermal equation of motion to describe the acceleration and analytically predicts the Alfvénic critical radius. We fit the model to near-Earth observations of the Wind spacecraft during the solar rotation period of 1-27 August 2010. The resulting data-driven model demonstrates the existence of noncorotating, nonradial flows and fields from the inner boundary (r = rs) outward and predicts the magnetic field B = (Br,Bϕ), velocity v = (vr,vϕ), and density n(r,ϕ,t), which vary with heliocentric distance r, heliolatitude ϕ, and time t in a Sun-centered standard inertial plane. The description applies formally only in the equatorial plane. In a frame corotating with the Sun, the transformed velocity v' and a field B' are not parallel, resulting in an electric field with a component Ez' along the z axis. The resulting E'×B'=E'×B drift lies in the equatorial plane, while the ∇B and curvature drifts are out of the plane. Together these may lead to enhanced scattering/heating of sufficiently energetic particles. The model predicts that deviations δvϕ from corotation at the inner boundary are common, with δvϕ(rs,ϕs,ts) comparable to the transverse velocities due to granulation and supergranulation motions. Abrupt changes in δvϕ(rs,ϕs,ts) are interpreted in terms of converging and diverging flows at the cell boundaries and centers, respectively. Large-scale variations in the predicted angular momentum demonstrate that the solar wind can drive vorticity and turbulence from near the Sun to 1 AU and beyond.

The Western Wind and Solar Integration Study Phase 2

Energy Technology Data Exchange (ETDEWEB)

Lew, Debra [National Renewable Energy Lab. (NREL), Golden, CO (United States); Brinkman, Greg [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ibanez, E. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Florita, A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Heaney, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hodge, B. -M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hummon, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Stark, G. [National Renewable Energy Lab. (NREL), Golden, CO (United States); King, J. [RePPAE; Lefton, S. A. [Intertek-APTECH, Houston, TX (United States); Kumar, N. [Intertek-APTECH, Houston, TX (United States); Agan, D. [Intertek-APTECH, Houston, TX (United States); Jordan, G. [GE Energy, Fairfield, CT (United States); Venkataraman, S. [GE Energy, Fairfield, CT (United States)

2013-09-01

The electric grid is a highly complex, interconnected machine, and changing one part of the grid can have consequences elsewhere. Adding wind and solar affects the operation of the other power plants and adding high penetrations can induce cycling of fossil-fueled generators. Cycling leads to wear-and-tear costs and changes in emissions. Phase 2 of the Western Wind and Solar Integration Study (WWSIS-2) evaluated these costs and emissions and simulated grid operations for a year to investigate the detailed impact of wind and solar on the fossil-fueled fleet. This built on Phase 1, one of the largest wind and solar integration studies ever conducted, which examined operational impacts of high wind and solar penetrations in the West(GE Energy 2010).

The Western Wind and Solar Integration Study Phase 2

Energy Technology Data Exchange (ETDEWEB)

Lew, D.; Brinkman, G.; Ibanez, E.; Hodge, B. M.; Hummon, M.; Florita, A.; Heaney, M.

2013-09-01

The electric grid is a highly complex, interconnected machine, and changing one part of the grid can have consequences elsewhere. Adding wind and solar affects the operation of the other power plants and adding high penetrations can induce cycling of fossil-fueled generators. Cycling leads to wear-and-tear costs and changes in emissions. Phase 2 of the Western Wind and Solar Integration Study (WWSIS-2) evaluated these costs and emissions and simulated grid operations for a year to investigate the detailed impact of wind and solar on the fossil-fueled fleet. This built on Phase 1, one of the largest wind and solar integration studies ever conducted, which examined operational impacts of high wind and solar penetrations in the West.

WIND observations of coherent electrostatic waves in the solar wind

Directory of Open Access Journals (Sweden)

A. Mangeney

Full Text Available The time domain sampler (TDS experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near the Lagrange point L1. In the range of frequencies above the proton plasma frequency f_pi and smaller than or of the order of the electron plasma frequency f_pe, TDS observed three kinds of electrostatic (e.s. waves: coherent wave packets of Langmuir waves with frequencies f ~ f_pe, coherent wave packets with frequencies in the ion acoustic range f_pi < f < f_pe, and more or less isolated non-sinusoidal spikes lasting less than 1 ms. We confirm that the observed frequency of the low frequency (LF ion acoustic wave packets is dominated by the Doppler effect: the wavelengths are short, 10 to 50 electron Debye lengths λ_D. The electric field in the isolated electrostatic structures (IES and in the LF wave packets is more or less aligned with the solar wind magnetic field. Across the IES, which have a spatial width of the order of ~ 25λ_D, there is a small but finite electric potential drop, implying an average electric field generally directed away from the Sun. The IES wave forms, which have not been previously reported in the solar wind, are similar, although with a smaller amplitude, to the weak double layers observed in the auroral regions, and to the electrostatic solitary waves observed in other regions in the magnetosphere. We have also studied the solar wind conditions which favour the occurrence of the three kinds of waves: all these e.s. waves are observed more or less continuously in the whole solar wind (except in the densest regions where a parasite prevents the TDS observations. The type (wave packet or IES of the observed LF waves is mainly determined

The solar wind at solar maximum: comparisons of EISCAT IPS and in situ observations

Directory of Open Access Journals (Sweden)

A. R. Breen

Full Text Available The solar maximum solar wind is highly structured in latitude, longitude and in time. Coronal measurements show a very high degree of variability, with large variations that are less apparent within in situ spacecraft measurements. Interplanetary scintillation (IPS observations from EISCAT, covering distances from 20 to 100 solar radii (R_S, are an ideal source of information on the inner solar wind and can be used, therefore, to cast light on its evolution with distance from the Sun. Earlier comparisons of in situ and IPS measurements under solar minimum conditions showed good large-scale agreement, particularly in the fast wind. In this study we attempt a quantitative comparison of measurements made over solar maximum by EISCAT (20–100 R_S and the Wind and Ulysses spacecraft (at 215 R_S and 300–1000 R_S, respectively. The intervals studied were August–September 1999, May 2000, September 2000 and May 2001, the last-named being the period of the second Ulysses fast latitude scan. Both ballistic and – when possible – MHD/ballistic hybrid models were used to relate the data sets, and we compare the results obtained from these two mapping methods. The results of this study suggest that solar wind velocities measured in situ were less variable than those estimated from IPS measurements closer to the Sun, with the greatest divergence between IPS velocities and in situ measurements occurring in regions where steep longitudinal velocity gradients were seen in situ. We suggest that the interaction between streams of solar wind with different velocities leads to "smoothing" of solar wind velocities between 30–60 R_S and 1 AU, and that this process continues at greater distances from the Sun.

Key words. Interplanetary physics (solar wind plasma; sources of the solar wind; instruments and techniques

Solar Process Heat Basics | NREL

Science.gov (United States)

Process Heat Basics Solar Process Heat Basics Commercial and industrial buildings may use the same solar technologies-photovoltaics, passive heating, daylighting, and water heating-that are used for residential buildings. These nonresidential buildings can also use solar energy technologies that would be

Regulation of ion drifts and anisotropies by parametrically unstable finite-amplitude Alfvén-cyclotron waves in the fast solar wind

Energy Technology Data Exchange (ETDEWEB)

Maneva, Y. G. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Araneda, J. A. [Departamento de Física, Universidad de Concepción, 4070386 (Chile); Marsch, E., E-mail: yana.g.maneva@nasa.gov [Institute for Experimental and Applied Physics, Christian Albrechts University at Kiel, D-24118 Kiel (Germany)

2014-03-10

We study the preferential heating and differential acceleration of minor ions by dissipation of ion-acoustic waves (IAWs) generated by parametric instabilities of a finite-amplitude monochromatic Alfvén-cyclotron pump wave. We consider the associated kinetic effects of Landau damping and nonlinear pitch-angle scattering of protons and α particles in the tenuous plasma of coronal holes and the fast solar wind. Various data collected by Wind spacecraft show signatures for a local transverse heating of the minor ions, presumably by Alfvén-cyclotron wave dissipation, and an unexpected parallel heating by a so far unknown mechanism. Here, we present the results from a set of 1.5 dimensional hybrid simulations in search for a plausible explanation for the observed field-aligned kinetic features in the fast solar wind minor ions. We investigate the origin and regulation of ion relative drifts and temperature anisotropies in low plasma β, fast solar wind conditions. Depending on their initial drifts, both ion species can heat up not only transversely through cyclotron resonance and non-resonant wave-particle interactions, but also strongly in the parallel direction by Landau damping of the daughter IAWs. We discuss the dependence of the relative ion drifts and temperature anisotropies on the plasma β of the individual species and we describe the effect of the pump wave amplitude on the ion heating and acceleration.

CONDITIONED ANALYSIS OF HIGH-LATITUDE SOLAR WIND INTERMITTENCY

International Nuclear Information System (INIS)

D'Amicis, R.; Consolini, G.; Bavassano, B.; Bruno, R.

2012-01-01

The solar wind is a turbulent medium displaying intermittency. Its intermittent features have been widely documented and studied, showing how the intermittent character is different in fast and slow wind. In this paper, a statistical conditioned analysis of the solar wind intermittency for a period of high-latitude fast solar wind is presented. In particular, the intermittent features are investigated as a function of the Alfvénic degree of fluctuations at a given scale. The results show that the main contribution to solar wind intermittency is due to non-Alfvénic structures, while Alfvénic increments are found to be characterized by a smaller level of intermittency than the previous ones. Furthermore, the lifetime statistics of Alfvénic periods are discussed in terms of a multiscale texture of randomly oriented flux tubes.

Alfvénic fluctuations in "newborn"' polar solar wind

Directory of Open Access Journals (Sweden)

B. Bavassano

2005-06-01

Full Text Available The 3-D structure of the solar wind is strongly dependent upon the Sun's activity cycle. At low solar activity a bimodal structure is dominant, with a fast and uniform flow at the high latitudes, and slow and variable flows at low latitudes. Around solar maximum, in sharp contrast, variable flows are observed at all latitudes. This last kind of pattern, however, is a relatively short-lived feature, and quite soon after solar maximum the polar wind tends to regain its role. The plasma parameter distributions for these newborn polar flows appear very similar to those typically observed in polar wind at low solar activity. The point addressed here is about polar wind fluctuations. As is well known, the low-solar-activity polar wind is characterized by a strong flow of Alfvénic fluctuations. Does this hold for the new polar flows too? An answer to this question is given here through a comparative statistical analysis on parameters such as total energy, cross helicity, and residual energy, that are of general use to describe the Alfvénic character of fluctuations. Our results indicate that the main features of the Alfvénic fluctuations observed in low-solar-activity polar wind have been quickly recovered in the new polar flows developed shortly after solar maximum. Keywords. Interplanetary physics (MHD waves and turbulence; Sources of the solar wind – Space plasma physics (Turbulence

The influence of solar wind variability on magnetospheric ULF wave power

International Nuclear Information System (INIS)

Pokhotelov, D.; Rae, I.J.; Mann, I.R.

2015-01-01

Magnetospheric ultra-low frequency (ULF) oscillations in the Pc 4-5 frequency range play an important role in the dynamics of Earth's radiation belts, both by enhancing the radial diffusion through incoherent interactions and through the coherent drift-resonant interactions with trapped radiation belt electrons. The statistical distributions of magnetospheric ULF wave power are known to be strongly dependent on solar wind parameters such as solar wind speed and interplanetary magnetic field (IMF) orientation. Statistical characterisation of ULF wave power in the magnetosphere traditionally relies on average solar wind-IMF conditions over a specific time period. In this brief report, we perform an alternative characterisation of the solar wind influence on magnetospheric ULF wave activity through the characterisation of the solar wind driver by its variability using the standard deviation of solar wind parameters rather than a simple time average. We present a statistical study of nearly one solar cycle (1996-2004) of geosynchronous observations of magnetic ULF wave power and find that there is significant variation in ULF wave powers as a function of the dynamic properties of the solar wind. In particular, we find that the variability in IMF vector, rather than variabilities in other parameters (solar wind density, bulk velocity and ion temperature), plays the strongest role in controlling geosynchronous ULF power. We conclude that, although time-averaged bulk properties of the solar wind are a key factor in driving ULF powers in the magnetosphere, the solar wind variability can be an important contributor as well. This highlights the potential importance of including solar wind variability especially in studies of ULF wave dynamics in order to assess the efficiency of solar wind-magnetosphere coupling.

THREE-DIMENSIONAL EVOLUTION OF SOLAR WIND DURING SOLAR CYCLES 22–24

International Nuclear Information System (INIS)

Manoharan, P. K.

2012-01-01

This paper presents an analysis of three-dimensional evolution of solar wind density turbulence and speed at various levels of solar activity between solar cycles 22 and 24. The solar wind data used in this study have been obtained from the interplanetary scintillation (IPS) measurements made at the Ooty Radio Telescope, operating at 327 MHz. Results show that (1) on average, there was a downward trend in density turbulence from the maximum of cycle 22 to the deep minimum phase of cycle 23; (2) the scattering diameter of the corona around the Sun shrunk steadily toward the Sun, starting from 2003 to the smallest size at the deepest minimum, and it corresponded to a reduction of ∼50% in the density turbulence between the maximum and minimum phases of cycle 23; (3) the latitudinal distribution of the solar wind speed was significantly different between the minima of cycles 22 and 23. At the minimum phase of solar cycle 22, when the underlying solar magnetic field was simple and nearly dipole in nature, the high-speed streams were observed from the poles to ∼30° latitudes in both hemispheres. In contrast, in the long-decay phase of cycle 23, the sources of the high-speed wind at both poles, in accordance with the weak polar fields, occupied narrow latitude belts from poles to ∼60° latitudes. Moreover, in agreement with the large amplitude of the heliospheric current sheet, the low-speed wind prevailed in the low- and mid-latitude regions of the heliosphere. (4) At the transition phase between cycles 23 and 24, the high levels of density and density turbulence were observed close to the heliospheric equator and the low-speed solar wind extended from the equatorial-to-mid-latitude regions. The above results in comparison with Ulysses and other in situ measurements suggest that the source of the solar wind has changed globally, with the important implication that the supply of mass and energy from the Sun to the interplanetary space has been significantly reduced

Wave-trains in the solar wind. III

International Nuclear Information System (INIS)

Richter, A.K.

1975-01-01

Applying an Alfven-Wave-Extended-QRH-approximation and the method of characteristics, the equations of motion for outwardly propagating Alfven waves are solved analytically for three different cases of an azimuthal dependence of the background solar wind, (a) for a pure fast-slow stream configuration, (b) for the situation where the high-speed stream originates from a diverging magnetic field, and (c) for the case of (b) and an initially decreasing density configuration ('coronal hole'). The reaction of these waves on the background state as well as mode-mode coupling effects are neglected. These three solar wind models are discussed shortly. For the superimposed Alfven waves it is found, on an average, that there is a strong azimuthal dependence of all relevant parameters which, correlated with the azimuthal distributions of the solar wind variables, leads to good agreements with observations. The signature of high-speed streams and these correlations could clearly indicate solar wind streams originating from 'coronal holes'. Contrary to the purely radial solar wind, where outwardly propagating Alfven waves are exclusively refracted towards the radial direction, a refraction nearly perpendicular to the direction of the interplanetary magnetic field in the compression region and closely towards the magnetic field direction down the trailing edge and in the low-speed regime is found. (Auth.)

Large-scale solar heat

Energy Technology Data Exchange (ETDEWEB)

Tolonen, J.; Konttinen, P.; Lund, P. [Helsinki Univ. of Technology, Otaniemi (Finland). Dept. of Engineering Physics and Mathematics

1998-12-31

In this project a large domestic solar heating system was built and a solar district heating system was modelled and simulated. Objectives were to improve the performance and reduce costs of a large-scale solar heating system. As a result of the project the benefit/cost ratio can be increased by 40 % through dimensioning and optimising the system at the designing stage. (orig.)

Genesis Solar Wind Science Canister Components Curated as Potential Solar Wind Collectors and Reference Contamination Sources

Science.gov (United States)

Allton, J. H.; Gonzalez, C. P.; Allums, K. K.

2016-01-01

The Genesis mission collected solar wind for 27 months at Earth-Sun L1 on both passive and active collectors carried inside of a Science Canister, which was cleaned and assembled in an ISO Class 4 cleanroom prior to launch. The primary passive collectors, 271 individual hexagons and 30 half-hexagons of semiconductor materials, are described in. Since the hard landing reduced the 301 passive collectors to many thousand smaller fragments, characterization and posting in the online catalog remains a work in progress, with about 19% of the total area characterized to date. Other passive collectors, surfaces of opportunity, have been added to the online catalog. For species needing to be concentrated for precise measurement (e.g. oxygen and nitrogen isotopes) an energy-independent parabolic ion mirror focused ions onto a 6.2 cm diameter target. The target materials, as recovered after landing, are described in. The online catalog of these solar wind collectors, a work in progress, can be found at: http://curator.jsc.nasa.gov/gencatalog/index.cfm This paper describes the next step, the cataloging of pieces of the Science Canister, which were surfaces exposed to the solar wind or component materials adjacent to solar wind collectors which may have contributed contamination.

Proton thermal energetics in the solar wind: Helios reloaded

Czech Academy of Sciences Publication Activity Database

Hellinger, Petr; Trávníček, Pavel M.; Štverák, Štěpán; Matteini, L.; Velli, M.

2013-01-01

Roč. 118, č. 4 (2013), s. 3151-3165 ISSN 2169-9380 R&D Projects: GA ČR GAP209/12/2041; GA ČR GAP209/12/2023 EU Projects: European Commission(XE) 263340 - SWIFF Grant - others:EU(XE) SHOCK Project No. 284515 Institutional support: RVO:67985815 ; RVO:68378289 Keywords : solar wind * proton energetics * turbulent heating Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics; BL - Plasma and Gas Discharge Physics (UFA-U) Impact factor: 3.440, year: 2013

An overview of the photovoltaic, wind power, solar water heating and small-scale hydropower supply industries in South Africa up to 1994/95

International Nuclear Information System (INIS)

Stassen, G.; Holm, D.

1997-01-01

This paper contains a broad overview of the South African photovoltaic, solar water heating, wind power and small-scale hydropower industries. Against the general lack of a comprehensive national database on renewable energy supply and demand, this overview attempts to provide general background information on these commercial industries, market trends, local sales figures, export volumes and installed capacity estimates. It also identifies the industry's major constraints, as well as their future outlook. (author). 12 refs., 13 tabs., 4 figs

Observation of solar wind with radio-star scintillation

International Nuclear Information System (INIS)

Watanabe, Takashi

1974-01-01

Large solar flares occurred in groups in early August 1972, and many interesting phenomena were observed. The solar wind condition during this period, obtained by scintillation observation, is reviewed. The velocity of solar wind has been determined from the observation of interplanetary space scintillation at Toyokawa, Fujigamine and Sugadaira. Four to ten radio wave sources were observed for ten minutes at each southing every day. Strong earth magnetic storm and the Forbush decrease of cosmic ray were observed during the period from August 3rd to 7th. Pioneer 9 observed a solar wind having the maximum velocity as high as 1,100 km/sec, and HEOS-II observed a solar wind having the velocity close to 2,000 km/sec. On the other hand, according to the scintillation of 3C-48 and 3C-144, the velocity of solar wind passing in the interplanetary space on the westside of the earth was only 300 to 400 km/sec. Therefore it is considered that the condition of solar wind on the east side of the earth differs from that on the west side of the earth. Pioneer 9 observed the pass of a shock wave on August 9th. With all radio wave sources, high velocity solar wind was observed and Pioneer 6 positioned on the west side of the earth also observed it. The thickness of this shock wave is at least 0.3 AU. Discussion is made on the cause for the difference between the asymmetric shock wave in the direction of south-west and symmetrical shock wave. The former may be blast wave, and the latter may be piston driven shock wave and the like. (Iwakiri, K.)

Solar wind controlled pulsations: A review

International Nuclear Information System (INIS)

Odera, T.J.

1986-01-01

Studies of the solar wind controlled Pc 3, 4 pulsations by early and recent researchers are highlighted. The review focuses on the recent observations, which cover the time during the International Magnetospheric Study (IMS). Results from early and recent observations agree on one point, that is, that the Pc 3, 4 pulsations are influenced by three main solar wind parameters, namely, the solar wind velocity V/sub 5w/, the IMF orientation theta/sub x/B, and magnitude B. The results can be interpreted, preferably, in terms of an external origin for Pc 3, 4 pulsations. This implies, essentially, the signal model, which means that the pulsations originate in the upstream waves (in the interplanetary medium) and are transported by convection to the magnetopause, where they couple to oscillations of the magnetospheric field lines

Passive solar heating

Energy Technology Data Exchange (ETDEWEB)

Wiberg, K

1981-11-10

The present work treats the possibilities for heating according to the passive solar heating method. Problems of 'spatial organization in an energy-saving society' are distinguished from among other social problems. The final delimination of the actual problems under investigation consists of the use of passive solar heating and especially the 'consequences of such solar heating exploitation upon the form and structures' of planning and construction. In the concluding chapter an applied example shows how this method can be used in designing an urban area and what are its limitations. The results indicate the possibilities and difficulties in attempting to transfer this ideal and general method into models and directives for form and structure from which examples of the actual possibilities in practical planning can be given.

Solar wind velocity and temperature in the outer heliosphere

Science.gov (United States)

Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J.

1994-01-01

At the end of 1992, the Pioneer 10, Pioneer 11, and Voyager 2 spacecraft were at heliocentric distances of 56.0, 37.3, and 39.0 AU and heliographic latitudes of 3.3 deg N, 17.4 deg N, and 8.6 deg S, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer 10 is on the opposite side of the Sun. All three spacecraft have working plasma analyzers, so intercomparison of data from these spacecraft provides important information about the global character of the solar wind in the outer heliosphere. The averaged solar wind speed continued to exhibit its well-known variation with solar cycle: Even at heliocentric distances greater than 50 AU, the average speed is highest during the declining phase of the solar cycle and lowest near solar minimum. There was a strong latitudinal gradient in solar wind speed between 3 deg and 17 deg N during the last solar minimum, but this gradient has since disappeared. The solar wind temperature declined with increasing heliocentric distance out to a heliocentric distance of at least 20 AU; this decline appeared to continue at larger heliocentric distances, but temperatures in the outer heliosphere were suprisingly high. While Pioneer 10 and Voyager 2 observed comparable solar wind temperatures, the temperature at Pioneer 11 was significantly higher, which suggests the existence of a large-scale variation of temperature with heliographic longitude. There was also some suggestion that solar wind temperatures were higher near solar minimum.

Wind and solar energy incentives in Iran

International Nuclear Information System (INIS)

Taleghani, G.; Kazemi Karegar, H.

2006-01-01

Incentive have yet been viewed as a means of supporting technological developments until a new technology becomes cost competitive wind based electricity is not jet generally competitive with alternate sources of electricity such as fossil fuels. This paper presents the potential for wind and solar in Iran and shows how much electric energy is now produced by renewable power plants compared to steam and gas. The importance of renewable energy effects on Iran environment and economy is also discussed and the issue of the contribution of renewable energy for producing electricity in the future will be shown. Also this paper highlights the ability of Iran to manufacture the components of the wind turbine and solar system locally, and its effect on the price of wind turbine and solar energy

Clouds blown by the solar wind

International Nuclear Information System (INIS)

Voiculescu, M; Condurache-Bota, S; Usoskin, I

2013-01-01

In this letter we investigate possible relationships between the cloud cover (CC) and the interplanetary electric field (IEF), which is modulated by the solar wind speed and the interplanetary magnetic field. We show that CC at mid–high latitudes systematically correlates with positive IEF, which has a clear energetic input into the atmosphere, but not with negative IEF, in general agreement with predictions of the global electric circuit (GEC)-related mechanism. Thus, our results suggest that mid–high latitude clouds might be affected by the solar wind via the GEC. Since IEF responds differently to solar activity than, for instance, cosmic ray flux or solar irradiance, we also show that such a study allows distinguishing one solar-driven mechanism of cloud evolution, via the GEC, from others. (letter)

Relationship between velocity gradients and magnetic turbulence in the solar wind

International Nuclear Information System (INIS)

Garrett, H.B.

1974-01-01

The correlations among the time derivative of the solar-wind velocity, the magnitude of the interplanetary magnetic field (IMF), and the IMF turbulence level are examined to test the idea that interaction between two colliding solar-wind streams can generate turbulence in the solar wind and the IMF. Data obtained by Explorer 33 on the solar wind and IMF are described, and the analysis techniques are outlined. The results indicate that the IMF turbulence level, as measured by the variance, is correlated with the existence of positive velocity gradients in the solar wind. It is noted that while the variance is an increasing function of the field magnitude, it is also independently correlated with the solar-wind velocity gradient

The effect of broad-band Alfven-cyclotron waves spectra on the preferential heating and differential acceleration of He{sup ++} ions in the solar wind

Energy Technology Data Exchange (ETDEWEB)

Maneva, Y. G. [Department of Physics, Catholic University of America, Washington DC, 20064 (United States) and Heliophysics Science Devision, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ofman, L. [Department of Physics, Catholic University of America, Washington, DC 20064 (United States) and Heliophysics Science Devision, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Vinas, A. F. [Heliophysics Science Devision, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-06-13

In anticipation of results from inner heliospheric missions such as the Solar Orbiter and the Solar Probe we present the results from 1.5D hybrid simulations to study the role of magnetic fluctuations for the heating and differential acceleration of He{sup ++} ions in the solar wind. We consider the effects of nonlinear Alfven-cyclotron waves at different frequency regimes. Monochromatic nonlinear Alfven-alpha-cyclotron waves are known to preferentially heat and accelerate He{sup ++} ions in collisionless low beta plasma. In this study we demonstrate that these effects are preserved when higherfrequency monochromatic and broad-band spectra of Alfven-proton-cyclotron waves are considered. Comparison between several nonlinear monochromatic waves shows that the ion temperatures, anisotropies and relative drift are quantitatively affected by the shift in frequency. Including a broad-band wave-spectrum results in a significant reduction of both the parallel and the perpendicular temperature components for the He{sup ++} ions, whereas the proton heating is barely influenced, with the parallel proton temperature only slightly enhanced. The differential streaming is strongly affected by the available wave power in the resonant daughter ion-acoustic waves. Therefore for the same initial wave energy, the relative drift is significantly reduced in the case of initial wave-spectra in comparison to the simulations with monochromatic waves.

Different magnetospheric modes: solar wind driving and coupling efficiency

Directory of Open Access Journals (Sweden)

N. Partamies

2009-11-01

Full Text Available This study describes a systematic statistical comparison of isolated non-storm substorms, steady magnetospheric convection (SMC intervals and sawtooth events. The number of events is approximately the same in each group and the data are taken from about the same years to avoid biasing by different solar cycle phase. The very same superposed epoch analysis is performed for each event group to show the characteristics of ground-based indices (AL, PCN, PC potential, particle injection at the geostationary orbit and the solar wind and IMF parameters. We show that the monthly occurrence of sawtooth events and isolated non-stormtime substorms closely follows maxima of the geomagnetic activity at (or close to the equinoxes. The most strongly solar wind driven event type, sawtooth events, is the least efficient in coupling the solar wind energy to the auroral ionosphere, while SMC periods are associated with the highest coupling ratio (AL/EY. Furthermore, solar wind speed seems to play a key role in determining the type of activity in the magnetosphere. Slow solar wind is capable of maintaining steady convection. During fast solar wind streams the magnetosphere responds with loading–unloading cycles, represented by substorms during moderately active conditions and sawtooth events (or other storm-time activations during geomagnetically active conditions.

Solar heating and cooling.

Science.gov (United States)

Duffie, J A

1976-01-01

Solar energy is discussed as an energy resource that can be converted into useful energy forms to meet a variety of energy needs. The review briefly explains the nature of this energy resource, the kinds of applications that can be made useful, and the status of several systems to which it has been applied. More specifically, information on solar collectors, solar water heating, solar heating of buildings, solar cooling plus other applications, are included.

Intermittency Statistics in the Expanding Solar Wind

Science.gov (United States)

Cuesta, M. E.; Parashar, T. N.; Matthaeus, W. H.

2017-12-01

The solar wind is observed to be turbulent. One of the open questions in solar wind research is how the turbulence evolves as the solar wind expands to great distances. Some studies have focused on evolution of the outer scale but not much has been done to understand how intermittency evolves in the expanding wind beyond 1 AU (see [1,2]). We use magnetic field data from Voyager I spacecraft from 1 to 10AU to study the evolution of statistics of magnetic discontinuities. We perform various statistical tests on these discontinuities and make connections to the physical processes occurring in the expanding wind.[1] Tsurutani, Bruce T., and Edward J. Smith. "Interplanetary discontinuities: Temporal variations and the radial gradient from 1 to 8.5 AU." Journal of Geophysical Research: Space Physics 84.A6 (1979): 2773-2787.[2] Greco, A., et al. "Evidence for nonlinear development of magnetohydrodynamic scale intermittency in the inner heliosphere." The Astrophysical Journal 749.2 (2012): 105.

Meteoric ions in the corona and solar wind

International Nuclear Information System (INIS)

Lemaire, J.

1990-01-01

The total mass of refractory material of interplanetary origin penetrating and evaporated in the meltosphere surrounding the sun has been inferred from observations of meteoroids and fireballs falling in earth's atmosphere. The amount of iron atoms deposited this way in the solar corona is of the order of 3000 t/s or larger. The measured flux of outflowing solar wind iron ions is equal to 2200 t/s. The close agreement of both fluxes is evidence that a significant fraction of iron ions observed in the solar wind and in the corona must be of meteoric origin. A similar accord is also obtained for silicon ions. The mean velocity of meteoroid ions formed in the solar corona is equal to the free-fall velocity: i.e., independent of their atomic mass as the thermal speed of heavy ion measured in low-density solar wind streams at 1 AU. Furthermore, the heavy ions of meteoric origin escape out of the corona with a larger bulk velocity than the protons which are mainly of solar origin. These differences of heavy ion and proton bulk velocities are also observed in the solar wind. 52 refs

Protons and alpha particles in the expanding solar wind: Hybrid simulations

Czech Academy of Sciences Publication Activity Database

Hellinger, Petr; Trávníček, Pavel M.

2013-01-01

Roč. 118, č. 9 (2013), s. 5421-5429 ISSN 2169-9380 R&D Projects: GA ČR GAP209/12/2023 Grant - others:EU(XE) SHOCK Project No. 284515 Institutional support: RVO:67985815 ; RVO:68378289 Keywords : solar wind * proton energetics * turbulent heating Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics; BL - Plasma and Gas Discharge Physics (UFA-U) Impact factor: 3.440, year: 2013

Solar heating cooling. Preparation of possible participation in IEA, Solar Heating Cooling Task 25; Solvarmedrevet koeling. Forberedelse af evt. deltagelse i IEA, Solar Heating Cooling Task 25

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

For the Danish solar heating industries it is interesting to discuss the domestic market possibilities and the export possibilities for solar heating cooling systems. The Danish solar heating sector also wants to participate in the international collaboration within IEA Solar Heating and Cooling Task 25 'Solar Assisted Air Conditioning of Buildings'. The Danish Energy Agency therefore has granted means for this project to discuss: The price of cooling for 3 different solar cooling methods (absorption cooling, desiccant cooling and ejector cooling); Market possibilities in Denmark and abroad; The advantages by Danish participation in IEA Task 25. The task has been solved through literature studies to establish status for the 3 technologies. It turned out that ejector cooling by low temperatures (85 deg. C from the solar collector) exists as pilot plants in relation to district heating, but is still not commercial accessible. Desiccant cooling, where the supplied heat has temperatures down to 55 deg. C is a well-developed technology. However only a handful of pilot plants with solar heating exists, and thus optimization relating to operation strategy and economy is on the experimental stage. Absorption cooling plants driven by solar heating are found in a large number in Japan and are also demonstrated in several other countries. The combination of absorption heating pump and solar heating is considered to be commercial accessible. Solar heating is interesting as heat source of to the exent that it can replace other sources of heat without the economy being depreciated. This can be the case in South Europe if: 1) oil or natural gas is used for heating; 2) a solar heating system already exists, e.g. for domestic water supply, and is installed so that the marginal costs by solar heating supply of the ventilation plant is reduced. All in all the above conditions mean that the market for solar heating for cooling is very limited in Europe, where almost

Electric solar wind sail mass budget model

Directory of Open Access Journals (Sweden)

P. Janhunen

2013-02-01

Full Text Available The electric solar wind sail (E-sail is a new type of propellantless propulsion system for Solar System transportation, which uses the natural solar wind to produce spacecraft propulsion. The E-sail consists of thin centrifugally stretched tethers that are kept charged by an onboard electron gun and, as such, experience Coulomb drag through the high-speed solar wind plasma stream. This paper discusses a mass breakdown and a performance model for an E-sail spacecraft that hosts a mission-specific payload of prescribed mass. In particular, the model is able to estimate the total spacecraft mass and its propulsive acceleration as a function of various design parameters such as the number of tethers and their length. A number of subsystem masses are calculated assuming existing or near-term E-sail technology. In light of the obtained performance estimates, an E-sail represents a promising propulsion system for a variety of transportation needs in the Solar System.

Magnetic fields in the solar system planets, moons and solar wind interactions

CERN Document Server

Wicht, Johannes; Gilder, Stuart; Holschneider, Matthias

2018-01-01

This book addresses and reviews many of the still little understood questions related to the processes underlying planetary magnetic fields and their interaction with the solar wind. With focus on research carried out within the German Priority Program ”PlanetMag”, it also provides an overview of the most recent research in the field. Magnetic fields play an important role in making a planet habitable by protecting the environment from the solar wind. Without the geomagnetic field, for example, life on Earth as we know it would not be possible. And results from recent space missions to Mars and Venus strongly indicate that planetary magnetic fields play a vital role in preventing atmospheric erosion by the solar wind. However, very little is known about the underlying interaction between the solar wind and a planet’s magnetic field. The book takes a synergistic interdisciplinary approach that combines newly developed tools for data acquisition and analysis, computer simulations of planetary interiors an...

German central solar heating plants with seasonal heat storage

Energy Technology Data Exchange (ETDEWEB)

Bauer, D.; Marx, R.; Nussbicker-Lux, J.; Ochs, F.; Heidemann, W. [Institute of Thermodynamics and Thermal Engineering (ITW), University of Stuttgart, Pfaffenwaldring 6, D-70550 Stuttgart (Germany); Mueller-Steinhagen, H. [Institute of Thermodynamics and Thermal Engineering (ITW), University of Stuttgart, Pfaffenwaldring 6, D-70550 Stuttgart (Germany); Institute of Technical Thermodynamics (ITT), German Aerospace Centre (DLR), Stuttgart (Germany)

2010-04-15

Central solar heating plants contribute to the reduction of CO{sub 2}-emissions and global warming. The combination of central solar heating plants with seasonal heat storage enables high solar fractions of 50% and more. Several pilot central solar heating plants with seasonal heat storage (CSHPSS) built in Germany since 1996 have proven the appropriate operation of these systems and confirmed the high solar fractions. Four different types of seasonal thermal energy stores have been developed, tested and monitored under realistic operation conditions: Hot-water thermal energy store (e.g. in Friedrichshafen), gravel-water thermal energy store (e.g. in Steinfurt-Borghorst), borehole thermal energy store (in Neckarsulm) and aquifer thermal energy store (in Rostock). In this paper, measured heat balances of several German CSHPSS are presented. The different types of thermal energy stores and the affiliated central solar heating plants and district heating systems are described. Their operational characteristics are compared using measured data gained from an extensive monitoring program. Thus long-term operational experiences such as the influence of net return temperatures are shown. (author)

Investigation on Solar Heating System with Building-Integrated Heat Storage

DEFF Research Database (Denmark)

Heller, Alfred

1996-01-01

Traditional solar heating systems cover between 5 and 10% of the heat demand fordomestic hot water and comfort heating. By applying storage capacity this share can beincreased much. The Danish producer of solar heating systems, Aidt-Miljø, markets such a system including storage of dry sand heated...... by PP-pipe heat exchanger. Heat demand is reduced due to direct solar heating and due to storage. The storage affects the heat demand passively due to higher temperatures. Hence heat loss is reduced and passive heating is optioned. In theory, by running the system flow backwards, active heating can...... solar collector area of the system, was achieved. Active heating from the sand storage was not observed. The pay-back time for the system can be estimated to be similar to solar heated domestic hot water systems in general. A number of minor improvements on the system could be pointed out....

Synoptic maps of solar wind parameters from in situ spacecraft observations

Science.gov (United States)

Gazis, P. R.

1995-01-01

Solar wind observations from the Interplanetary Monitoring Platform-8 (IMP-8) and Pioneer Venus Orbiter (PVO) spacecraft from 1982 until 1988 are combined to construct synoptic maps of solar wind parameters near 1 AU. Each map consists of 6 months of hourly averaged solar wind data, binned by heliographic latitude and Carrington longitude and projected back to the Sun. These maps show the structure and time evolution of solar wind streams near 1 AU in the heliographic latitudes of +/- 7.25 deg and provide and explicit picture of several phenomena, such as gradients, changes in the inclination of the heliospheric current sheet, and the relative positions of various structures in the inner heliosphere, that is difficult to obtain from single-spacecraft observations. The stream structure varied significantly during the last solar cycle. Between 1982 and early 1985, solar wind parameters did not depend strongly on heliographic latitude. During the last solar minimum, the solar wind developed significant latitudinal structure, and high-speed streams were excluded from the vicinity of the solar equator. The interplanetary magnetic field was strongly correlated with the coronal field, and the current sheet tended to coincide with the coronal neutral line. The solar wind speed showed the expected correlations with temperature, interplanetary magnetic field, and distance from the current sheet. The solar wind speed was anticorrelated with density, but the regions of highest density occurred east of the heliospheric current sheet and the regions of lowest solar wind speed. This is consistent with compression at the leading edge of high-speed streams.

The influence of solar wind variability on magnetospheric ULF wave power

Directory of Open Access Journals (Sweden)

D. Pokhotelov

2015-06-01

Full Text Available Magnetospheric ultra-low frequency (ULF oscillations in the Pc 4–5 frequency range play an important role in the dynamics of Earth's radiation belts, both by enhancing the radial diffusion through incoherent interactions and through the coherent drift-resonant interactions with trapped radiation belt electrons. The statistical distributions of magnetospheric ULF wave power are known to be strongly dependent on solar wind parameters such as solar wind speed and interplanetary magnetic field (IMF orientation. Statistical characterisation of ULF wave power in the magnetosphere traditionally relies on average solar wind–IMF conditions over a specific time period. In this brief report, we perform an alternative characterisation of the solar wind influence on magnetospheric ULF wave activity through the characterisation of the solar wind driver by its variability using the standard deviation of solar wind parameters rather than a simple time average. We present a statistical study of nearly one solar cycle (1996–2004 of geosynchronous observations of magnetic ULF wave power and find that there is significant variation in ULF wave powers as a function of the dynamic properties of the solar wind. In particular, we find that the variability in IMF vector, rather than variabilities in other parameters (solar wind density, bulk velocity and ion temperature, plays the strongest role in controlling geosynchronous ULF power. We conclude that, although time-averaged bulk properties of the solar wind are a key factor in driving ULF powers in the magnetosphere, the solar wind variability can be an important contributor as well. This highlights the potential importance of including solar wind variability especially in studies of ULF wave dynamics in order to assess the efficiency of solar wind–magnetosphere coupling.

Solar winds along curved magnetic field lines

OpenAIRE

Li, Bo; Xia, Li-Dong; Chen, Yao

2011-01-01

Both remote-sensing measurements using the interplanetary scintillation (IPS) technique and in situ measurements by the Ulysses spacecraft show a bimodal structure for the solar wind at solar minimum conditions. At present what makes the fast wind fast and the slow wind slow still remains to be answered. While a robust empirical correlation exists between the coronal expansion rate $f_c$ of the flow tubes and the speeds $v$ measured in situ, further data analysis suggests that $v$ depends on ...

Solar wind and its interaction with the Earth magnetosphere

International Nuclear Information System (INIS)

Grib, S.A.

1978-01-01

A critical review is given regarding the research of the stationary and non-stationary interaction of the solar wind with the Earth magnetosphere. Highlighted is the significance of the interplanetary magnetic field in the non-stationary movement of the solar wind flux. The problem of the solar wind shock waves interaction with the ''bow wave-Earth's magnetosphere'' system is being solved. Considered are the secondary phenomena, as a result of which the depression-type wave occurs, that lowers the pressure on the Earth's maanetosphere. The law, governing the movement of the magnetosphere subsolar point during the abrupt start of a geomagnetic storm has been discovered. Stationary circumvention of the magnetosphere by the solar wind flux is well described by the gas dynamic theory of the hypersonic flux. Non-stationary interaction of the solar wind shock waves with the magnetosphere is magnetohydrodynamic. It is pointed out, that the problems under consideration are important for the forecasting of strong geomagnetic perturbations on the basis of cosmic observations

A study of the solar wind deceleration in the Earth's foreshock region

Science.gov (United States)

Zhang, T.-L.; Schwingenschuh, K.; Russell, C. T.

1995-01-01

Previous observations have shown that the solar wind is decelerated and deflected in the earth's upstream region populated by long-period waves. This deceleration is corelated with the 'diffuse' but not with the 'reflected' ion population. The speed of the solar wind may decrease tens of km/s in the foreshock region. The solar wind dynamic pressure exerted on the magnetopause may vary due to the fluctuation of the solar wind speed and density in the foreshock region. In this study, we examine this solar wind deceleration and determine how the solar wind deceleration varies in the foreshock region.

Compact seasonal PCM heat storage for solar heating systems

DEFF Research Database (Denmark)

Dannemand, Mark

Space heating of buildings and preparation of domestic hot water accounts for a large part of the society’s energy consumption. Solar radiation is an abundant and renewable energy source which can be harvested by solar collectors and used to cover heating demands in the built environment....... The seasonal availability of solar energy does however not match with the heating demands in buildings which typically are large in winter periods when limited solar energy is available. Heat can be stored over a few days in water stores but continuous heat losses limits the storage periods. The possibility...... of storing heat from summer where solar energy is widely available to winter periods where the heating demands are large, allows for implementing more renewable energy in our energy system. The phase change material (PCM) sodium acetate trihydrate (SAT) melts at 58 °C. The melting process requires...

The model of unshocked deceleration of the solar wind

International Nuclear Information System (INIS)

Gidalevich, E.Ya.

1977-01-01

The motion of the Sun relative to the interstellar gas is considered as an hydrodynamic flow in a point-source field. Interstellar gas has been found to undergo considerable compaction as it is braked in the solar gravitational field. Solar-wind braking due to ion charge exchange processes on interstellar hydrogen atoms is discussed. It is shown that tangible solar-wind braking occurs at a distance of about 3x1O 14 cm from the Sun in the apex direction. In the opposite direction solar wind propagates freely

Weakest solar wind of the space age and the current 'MINI' solar maximum

International Nuclear Information System (INIS)

McComas, D. J.; Angold, N.; Elliott, H. A.; Livadiotis, G.; Schwadron, N. A.; Smith, C. W.; Skoug, R. M.

2013-01-01

The last solar minimum, which extended into 2009, was especially deep and prolonged. Since then, sunspot activity has gone through a very small peak while the heliospheric current sheet achieved large tilt angles similar to prior solar maxima. The solar wind fluid properties and interplanetary magnetic field (IMF) have declined through the prolonged solar minimum and continued to be low through the current mini solar maximum. Compared to values typically observed from the mid-1970s through the mid-1990s, the following proton parameters are lower on average from 2009 through day 79 of 2013: solar wind speed and beta (∼11%), temperature (∼40%), thermal pressure (∼55%), mass flux (∼34%), momentum flux or dynamic pressure (∼41%), energy flux (∼48%), IMF magnitude (∼31%), and radial component of the IMF (∼38%). These results have important implications for the solar wind's interaction with planetary magnetospheres and the heliosphere's interaction with the local interstellar medium, with the proton dynamic pressure remaining near the lowest values observed in the space age: ∼1.4 nPa, compared to ∼2.4 nPa typically observed from the mid-1970s through the mid-1990s. The combination of lower magnetic flux emergence from the Sun (carried out in the solar wind as the IMF) and associated low power in the solar wind points to the causal relationship between them. Our results indicate that the low solar wind output is driven by an internal trend in the Sun that is longer than the ∼11 yr solar cycle, and they suggest that this current weak solar maximum is driven by the same trend.

Solar heating and cooling of buildings

Science.gov (United States)

Bourke, R. D.; Davis, E. S.

1975-01-01

Solar energy has been used for space heating and water heating for many years. A less common application, although technically feasible, is solar cooling. This paper describes the techniques employed in the heating and cooling of buildings, and in water heating. The potential for solar energy to displace conventional energy sources is discussed. Water heating for new apartments appears to have some features which could make it a place to begin the resurgence of solar energy applications in the United States. A project to investigate apartment solar water heating, currently in the pilot plant construction phase, is described.

Harnessing solar heat

CERN Document Server

Norton, Brian

2013-01-01

Systems engineered by man to harness solar heat in a controlled manner now include a diverse range of technologies each serving distinctive needs in particular climate contexts. This text covers the breadth of solar energy technologies for the conversion of solar energy to provide heat, either as the directly-used output or as an intermediary to other uses such as power generation or cooling. It is a wholly updated, extended and revised version of “Solar Energy Thermal Technology” first published in 1992. The text draws on the own author’s research and that of numerous colleagues and

Ensemble downscaling in coupled solar wind-magnetosphere modeling for space weather forecasting.

Science.gov (United States)

Owens, M J; Horbury, T S; Wicks, R T; McGregor, S L; Savani, N P; Xiong, M

2014-06-01

Advanced forecasting of space weather requires simulation of the whole Sun-to-Earth system, which necessitates driving magnetospheric models with the outputs from solar wind models. This presents a fundamental difficulty, as the magnetosphere is sensitive to both large-scale solar wind structures, which can be captured by solar wind models, and small-scale solar wind "noise," which is far below typical solar wind model resolution and results primarily from stochastic processes. Following similar approaches in terrestrial climate modeling, we propose statistical "downscaling" of solar wind model results prior to their use as input to a magnetospheric model. As magnetospheric response can be highly nonlinear, this is preferable to downscaling the results of magnetospheric modeling. To demonstrate the benefit of this approach, we first approximate solar wind model output by smoothing solar wind observations with an 8 h filter, then add small-scale structure back in through the addition of random noise with the observed spectral characteristics. Here we use a very simple parameterization of noise based upon the observed probability distribution functions of solar wind parameters, but more sophisticated methods will be developed in the future. An ensemble of results from the simple downscaling scheme are tested using a model-independent method and shown to add value to the magnetospheric forecast, both improving the best estimate and quantifying the uncertainty. We suggest a number of features desirable in an operational solar wind downscaling scheme. Solar wind models must be downscaled in order to drive magnetospheric models Ensemble downscaling is more effective than deterministic downscaling The magnetosphere responds nonlinearly to small-scale solar wind fluctuations.

Conductive solar wind models in rapidly diverging flow geometries

International Nuclear Information System (INIS)

Holzer, T.E.; Leer, E.

1980-01-01

A detailed parameter study of conductive models of the solar wind has been carried out, extending the previous similar studies of Durney (1972) and Durney and Hundhausen (1974) by considering collisionless inhibition of thermal conduction, rapidly diverging flow geometries, and the structure of solutions for the entire n 0 -T 0 plane (n 0 and T 0 are the coronal base density and temperature). Primary emphasis is placed on understanding the complex effects of the physical processes operative in conductive solar wind models. There are five points of particular interest that have arisen from the study: (1) neither collisionless inhibition of thermal conduction nor rapidly diverging flow geometries can significantly increase the solar wind speed at 1 AU; (2) there exists a firm upper limit on the coronal base temperature consistent with observed values of the coronal base pressure and solar wind mass flux density; (3) the principal effect of rapidly diverging flow geometries is a decrease in the solar wind mass flux density at 1 AU and an increase in the mass flux density at the coronal base; (4) collisionless inhibition of thermal conduction can lead to a solar wind flow speed that either increases or decreases with increasing coronal base density (n 0 ) and temperature (T 0 , depending on the region of the n 0 -T 0 plane considered; (5) there is a region of the n 0 -T/sub o/ plane at high coronal base densities where low-speed, high-mass-flux, transonic solar wind flows exist: a region not previously considered

Renewable Energy Systems: Development and Perspectives of a Hybrid Solar-Wind System

Directory of Open Access Journals (Sweden)

C. Shashidhar

2012-02-01

Full Text Available Considering the intermittent natural energy resources and the seasonal un-balance, a phtovoltaic-wind hybrid electrical power supply system was developed to accommodate remote locations where a conventional grid connection is inconvenient or expensive. However, the hybrid system can also be applied with grid connection and owners are allowed to sell excessive power back to the electric utility. The proposed set-up consists of a photo-voltaic solar-cell array, a mast mounted wind generator, lead-acid storage batteries, an inverter unit to convert DC to AC, electrical lighting loads, electrical heating loads, several fuse and junction boxes and associated wiring, and test instruments for measuring voltages, currents, power factors, and harmonic contamination data throughout the system. The proposed hybrid solar-wind power generating system can be extensively used to illustrate electrical concepts in hands-on laboratories and also for demonstrations in the Industrial Technology curriculum. This paper describes an analysis of local PV-wind hybrid systems for supplying electricity to a private house, farmhouse or small company with electrical power depending on the site needs. The major system components, work principle and specific working condition are presented.

Charge States of Krypton and Xenon in the Solar Wind

Science.gov (United States)

Bochsler, Peter; Fludra, Andrzej; Giunta, Alessandra

2017-09-01

We calculate charge state distributions of Kr and Xe in a model for two different types of solar wind using the effective ionization and recombination rates provided from the OPEN_ADAS data base. The charge states of heavy elements in the solar wind are essential for estimating the efficiency of Coulomb drag in the inner corona. We find that xenon ions experience particularly low Coulomb drag from protons in the inner corona, comparable to the notoriously weak drag of protons on helium ions. It has been found long ago that helium in the solar wind can be strongly depleted near interplanetary current sheets, whereas coronal mass ejecta are sometimes strongly enriched in helium. We argue that if the extraordinary variability of the helium abundance in the solar wind is due to inefficient Coulomb drag, the xenon abundance must vary strongly. In fact, a secular decrease of the solar wind xenon abundance relative to the other heavier noble gases (Ne, Ar, Kr) has been postulated based on a comparison of noble gases in recently irradiated and ancient samples of ilmenite in the lunar regolith. We conclude that decreasing solar activity and decreasing frequency of coronal mass ejections over the solar lifetime might be responsible for a secularly decreasing abundance of xenon in the solar wind.

Diagnostics of the solar wind transition region

International Nuclear Information System (INIS)

Lotova, N.A.; Nagelis, Ya.V.; Rudnitskij, G.M.; Smirnova, T.V.; AN Latvijskoj SSR, Riga. Radioastrofizicheskaya Observatoriya; Moskovskij Gosudarstvennyj Univ.; AN SSSR, Moscow. Fizicheskij Inst.)

1988-01-01

Possibilities are discussed of a more complete study of hardly observable regions of the interplanetary medium, in the zone of the solar wind formation, where transition from subsonic to supersonic flow occurs at R sun . It is shown that an investigation of fine structure of the extended transonic region of the solar wind and of the sequence of changes in the parameters of the interplanetary plasma in the region of the solar wind formation with the changing distance from the Sun can be effectuated by using jointly different modifications of the occupation method. Combination of two or more modifications of this method supposes using compact radio sources of different classes and observations in two different wavelength ranges, namely at short centimeter and at meter waves

Research programme 'Active Solar Energy Use - Solar Heating and Heat Storage'. Activities and projects 2003

International Nuclear Information System (INIS)

Hadorn, J.-C.; Renaud, P.

2003-01-01

In this report by the research, development and demonstration (RD+D) programme coordinators the objectives, activities and main results in the area of solar heating and heat storage in Switzerland are presented for 2003. In a stagnating market environment the strategy of the Swiss Federal Office of Energy mainly consists in improving the quality and durability of solar collectors and materials, optimizing combisystems for space heating and domestic hot water preparation, searching for storage systems with a higher energy storage density than in the case of sensible heat storage in water, developing coloured solar collectors for more architectonic freedom, and finalizing a seasonal heat storage project for 100 dwellings to demonstrate the feasibility of solar fractions larger than 50% in apartment houses. Support was granted to the Swiss Testing Facility SPF in Rapperswil as in previous years; SPF was the first European testing institute to perform solar collector labeling according to the new rules of the 'Solar Keymark', introduced in cooperation with the European Committee for Standardization CEN. Several 2003 projects were conducted within the framework of the Solar Heating and Cooling Programme of the International Energy Agency IEA. Computerized simulation tools were improved. With the aim of jointly producing high-temperature heat and electric power a solar installation including a concentrating collector and a thermodynamic machine based on a Rankine cycle is still being developed. Seasonal underground heat storage was studied in detail by means of a validated computer simulation programme. Design guidelines were obtained for such a storage used in the summer time for cooling and in the winter time for space heating via a heat pump: depending on the ratio 'summer cooling / winter heating', cooling requires a cooling machine, or direct cooling without such a machine is possible. The report ends up with the list of all supported RD+D projects

A comparison of solar wind streams and coronal structure near solar minimum

Science.gov (United States)

Nolte, J. T.; Davis, J. M.; Gerassimenko, M.; Lazarus, A. J.; Sullivan, J. D.

1977-01-01

Solar wind data from the MIT detectors on the IMP 7 and 8 satellites and the SOLRAD 11B satellite for the solar-minimum period September-December, 1976, were compared with X-ray images of the solar corona taken by rocket-borne telescopes on September 16 and November 17, 1976. There was no compelling evidence that a coronal hole was the source of any high speed stream. Thus it is possible that either coronal holes were not the sources of all recurrent high-speed solar wind streams during the declining phase of the solar cycle, as might be inferred from the Skylab period, or there was a change in the appearance of some magnetic field regions near the time of solar minimum.

Effects of Solar Photovoltaic Panels on Roof Heat Transfer

Science.gov (United States)

Dominguez, A.; Klessl, J.; Samady, M.; Luvall, J. C.

2010-01-01

Building Heating, Ventilation and Air Conditioning (HVAC) is a major contributor to urban energy use. In single story buildings with large surface area such as warehouses most of the heat enters through the roof. A rooftop modification that has not been examined experimentally is solar photovoltaic (PV) arrays. In California alone, several GW in residential and commercial rooftop PV are approved or in the planning stages. With the PV solar conversion efficiency ranging from 5-20% and a typical installed PV solar reflectance of 16-27%, 53-79% of the solar energy heats the panel. Most of this heat is then either transferred to the atmosphere or the building underneath. Consequently solar PV has indirect effects on roof heat transfer. The effect of rooftop PV systems on the building roof and indoor energy balance as well as their economic impacts on building HVAC costs have not been investigated. Roof calculator models currently do not account for rooftop modifications such as PV arrays. In this study, we report extensive measurements of a building containing a flush mount and a tilted solar PV array as well as exposed reference roof. Exterior air and surface temperature, wind speed, and solar radiation were measured and thermal infrared (TIR) images of the interior ceiling were taken. We found that in daytime the ceiling surface temperature under the PV arrays was significantly cooler than under the exposed roof. The maximum difference of 2.5 C was observed at around 1800h, close to typical time of peak energy demand. Conversely at night, the ceiling temperature under the PV arrays was warmer, especially for the array mounted flat onto the roof. A one dimensional conductive heat flux model was used to calculate the temperature profile through the roof. The heat flux into the bottom layer was used as an estimate of the heat flux into the building. The mean daytime heat flux (1200-2000 PST) under the exposed roof in the model was 14.0 Watts per square meter larger than

Wind and Solar Curtailment: International Experience and Practices

DEFF Research Database (Denmark)

Lew, Debra; Bird, Lori; Milligan, Michael

2013-01-01

High penetrations of wind and solar generation on power systems are resulting in increasing curtailment. Wind and solar integration studies predict increased curtailment as penetration levels grow. This paper examines experiences with curtailment on bulk power systems internationally. It discusses...... how much curtailment is occurring, how it is occurring, why it is occurring, and what is being done to reduce curtailment. This summary is produced as part of the International Energy Agency Wind Task 25 on Design and Operation of Power Systems with Large Amounts of Wind Power....

Experimental and numerical analysis of convective heat losses from spherical cavity receiver of solar concentrator

Directory of Open Access Journals (Sweden)

Shewale Vinod C.

2017-01-01

Full Text Available Spherical cavity receiver of solar concentrator is made up of Cu tubing material having cavity diameter 385 mm to analyze the different heat losses such as conduction, convection and radiation. As the convection loss plays major role in heat loss analysis of cavity receiver, the experimental analysis is carried out to study convective heat loss for the temperature range of 55-75°C at 0°, 15°, 30°, 45°, 60°, and 90° inclination angle of downward facing cavity receiver. The numerical analysis is carried out to study convective heat loss for the low temperature range (55-75°C as well as high temperature range (150-300 °C for no wind condition only. The experimental set-up mainly consists of spherical cavity receiver which is insulated with glass wool insulation to reduce the heat losses from outside surface. The numerical analysis is carried out by using CFD software and the results are compared with the experimental results and found good agreement. The result shows that the convective loss increases with decrease in cavity inclination angle and decreases with decrease in mean cavity receiver temperature. The maximum losses are obtained at 0° inclination angle and the minimum losses are obtained at 90° inclination angle of cavity due to increase in stagnation zone in to the cavity from 0° to 90° inclination. The Nusselt number correlation is developed for the low temperature range 55-75°C based on the experimental data. The analysis is also carried out to study the effect of wind speed and wind direction on convective heat losses. The convective heat losses are studied for two wind speeds (3 m/s and 5 m/s and four wind directions [α is 0° (Side-on wind, 30°, 60°, and 90° (head-on wind]. It is found that the convective heat losses for both wind speed are higher than the losses obtained by no wind test. The highest heat losses are found for wind direction α is 60° with respect to receiver stand and lowest heat losses are found

Modeling Study of the Geospace System Response to the Solar Wind Dynamic Pressure Enhancement on 17 March 2015

Science.gov (United States)

Ozturk, D. S.; Zou, S.; Ridley, A. J.; Slavin, J. A.

2018-04-01

The global magnetosphere-ionosphere-thermosphere system is intrinsically coupled and susceptible to external drivers such as solar wind dynamic pressure enhancements. In order to understand the large-scale dynamic processes in the magnetosphere-ionosphere-thermosphere system due to the compression from the solar wind, the 17 March 2015 sudden commencement was studied in detail using global numerical models. This storm was one of the most geoeffective events of the solar cycle 24 with a minimum Dst of -222 nT. The Wind spacecraft recorded a 10-nPa increment in the solar wind dynamic pressure, while the interplanetary magnetic field BZ became further northward. The University of Michigan Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme global magnetohydrodynamic code was utilized to study the generation and propagation of perturbations associated with the compression of the magnetosphere system. In addition, the high-resolution electric potential and auroral power output from the magnetohydrodynamic model was used to drive the global ionosphere-thermosphere model to investigate the ionosphere-thermosphere system response to pressure enhancement. During the compression, the electric potentials and convection patterns in the polar ionosphere were significantly altered when the preliminary impulse and main impulse field-aligned currents moved from dayside to nightside. As a result of enhanced frictional heating, plasma and neutral temperatures increased at the locations where the flow speeds were enhanced, whereas the electron density dropped at these locations. In particular, the region between the preliminary impulse and main impulse field-aligned currents experienced the most significant heating with 1000-K ion temperature increase and 20-K neutral temperature increase within 2 min. Comparison of the simulation results with the Poker Flat Incoherent Scatter Radar observations showed reasonable agreements despite underestimated magnitudes.

Wind in the Solar System

Science.gov (United States)

McIntosh, Gordon

2010-01-01

As an astronomy instructor I am always looking for commonly experienced Earthly phenomena to help my students and me understand and appreciate similar occurrences elsewhere in the solar system. Recently I wrote short "TPT" articles on frost and precipitation. The present article is on winds in the solar system. A windy day or storm might…

The Solar Wind Source Cycle: Relationship to Dynamo Behavior

Science.gov (United States)

Luhmann, J. G.; Li, Y.; Lee, C. O.; Jian, L. K.; Petrie, G. J. D.; Arge, C. N.

2017-12-01

Solar cycle trends of interest include the evolving properties of the solar wind, the heliospheric medium through which the Sun's plasmas and fields interact with Earth and the planets -including the evolution of CME/ICMEs enroute. Solar wind sources include the coronal holes-the open field regions that constantly evolve with solar magnetic fields as the cycle progresses, and the streamers between them. The recent cycle has been notably important in demonstrating that not all solar cycles are alike when it comes to contributions from these sources, including in the case of ecliptic solar wind. In particular, it has modified our appreciation of the low latitude coronal hole and streamer sources because of their relative prevalence. One way to understand the basic relationship between these source differences and what is happening inside the Sun and on its surface is to use observation-based models like the PFSS model to evaluate the evolution of the coronal field geometry. Although the accuracy of these models is compromised around solar maximum by lack of global surface field information and the sometimes non-potential evolution of the field related to more frequent and widespread emergence of active regions, they still approximate the character of the coronal field state. We use these models to compare the inferred recent cycle coronal holes and streamer belt sources of solar wind with past cycle counterparts. The results illustrate how (still) hemispherically asymmetric weak polar fields maintain a complex mix of low-to-mid latitude solar wind sources throughout the latest cycle, with a related marked asymmetry in the hemispheric distribution of the ecliptic wind sources. This is likely to be repeated until the polar field strength significantly increases relative to the fields at low latitudes, and the latter symmetrize.

Extended neutral atmosphere effect on solar wind interaction with nonmagnetic bodies of the solar system

International Nuclear Information System (INIS)

Breus, T.K.; Krymskij, A.M.; Mitnitskij, V.Ya.

1987-01-01

Numeric modelling of the Venus flow-around by the solar wind with regard to stream loading by heavy ions, produced under photoionization of the Venus neutral oxygen corona, is conducted. It is shown, that this effect can account for a whole number of peculiarities related to the solar wind interaction with the planet which have not been clearly explained yet, namely, shock wave position, solar wind stream and magnetic field characteristics behind the front

Solar energy uses in home water heating systems; Utilizacao da energia solar em sistemas de aquecimento de agua residencial

Energy Technology Data Exchange (ETDEWEB)

Basso, Luiz Henrique

2008-07-01

The awareness of the importance of the environment has stimulated the study of new energy sources renewed and less pollutant. Amongst these sources, solar energy stands alone for being perennial and clean. The use of solar energy in systems of residential water heating, instead of the electric shower, can compliment the economy of electric energy, based on the Brazilian energy matrix. To know all the factors that influence the operation of a system of water heating by solar energy it is important the determination of its economic and technical viabilities and, distribution targeting in urban and agricultural residences. To evaluate equipment of water heating for solar energy in the region west of the Parana, Brazil, an archetype with similar characteristics to equipment used in residences for two inhabitants was built, to function with natural circulation or thermosyphon and without help of a complementary heating system. The room temperature and the speed of the wind were also evaluated, verifying its influence in the heating system. The equipment revealed technical viability, reaching the minimum temperature of 35 deg C for shower, whenever the solar radiation was above the 3500 W.m{sup -2}, for the majority of the studied days. The system operated without interruptions and it did not need maintenance, except for the monthly glass cleaning. Economic viability was clearly demonstrated since the useful life of the equipment exceeded the period of use to gain its investment. (author)

EVOLUTION OF THE RELATIONSHIPS BETWEEN HELIUM ABUNDANCE, MINOR ION CHARGE STATE, AND SOLAR WIND SPEED OVER THE SOLAR CYCLE

International Nuclear Information System (INIS)

Kasper, J. C.; Stevens, M. L.; Korreck, K. E.; Maruca, B. A.; Kiefer, K. K.; Schwadron, N. A.; Lepri, S. T.

2012-01-01

The changing relationships between solar wind speed, helium abundance, and minor ion charge state are examined over solar cycle 23. Observations of the abundance of helium relative to hydrogen (A He ≡ 100 × n He /n H ) by the Wind spacecraft are used to examine the dependence of A He on solar wind speed and solar activity between 1994 and 2010. This work updates an earlier study of A He from 1994 to 2004 to include the recent extreme solar minimum and broadly confirms our previous result that A He in slow wind is strongly correlated with sunspot number, reaching its lowest values in each solar minima. During the last minimum, as sunspot numbers reached their lowest levels in recent history, A He continued to decrease, falling to half the levels observed in slow wind during the previous minimum and, for the first time observed, decreasing even in the fastest solar wind. We have also extended our previous analysis by adding measurements of the mean carbon and oxygen charge states observed with the Advanced Composition Explorer spacecraft since 1998. We find that as solar activity decreased, the mean charge states of oxygen and carbon for solar wind of a given speed also fell, implying that the wind was formed in cooler regions in the corona during the recent solar minimum. The physical processes in the coronal responsible for establishing the mean charge state and speed of the solar wind have evolved with solar activity and time.

Solar wind plasma structure near a 'HELIOS-Perihelion'

International Nuclear Information System (INIS)

Kikuchi, H.

1979-01-01

The purpose of this paper is to introduce a couple of preliminary but important results obtained from HELIOS observation concerning solar wind plasma structure near a ''HELIOS-Perihelion'' among the data analyses in progress, partly in relation to laboratory plasma. Idealized profiles of the bulk velocity, density and temperature of solar wind near 0.3 AU as deduced from HELIOS A data and correlated K-coronal contours were obtained. During 1974 - 1976, the sun was in the period of declining cycle, and the coronal holes expanded to lower latitudes from northern and southern holes. There is general tendency that the northern coronal hole is somewhat larger than the southern coronal hole. In regards to solar wind velocity, there are two fast stream regions with velocity as high as 800 Km/sec. An electron spectrum measured near a HELIOS-Perihelion (0.3 AU) approximately in the solar direction is shown. Three regions can be distinguished in velocity distribution. The density contours of solar wind electrons in velocity space exhibit a narrow beam of electrons in the magnetic field direction close to the plane of observation. (Kato, T.)

The genesis solar-wind sample return mission

International Nuclear Information System (INIS)

Wiens, Roger C.

2009-01-01

The compositions of the Earth's crust and mantle, and those of the Moon and Mars, are relatively well known both isotopically and elementally. The same is true of our knowledge of the asteroid belt composition, based on meteorite analyses. Remote measurements of Venus, the Jovian atmosphere, and the outer planet moons, have provided some estimates of their compositions. The Sun constitutes a large majority, > 99%, of all the matter in the solar system. The elemental composition of the photosphere, the visible 'surface' of the Sun, is constrained by absorption lines produced by particles above the surface. Abundances for many elements are reported to the ±10 or 20% accuracy level. However, the abundances of other important elements, such as neon, cannot be determined in this way due to a relative lack of atomic states at low excitation energies. Additionally and most importantly, the isotopic composition of the Sun cannot be determined astronomically except for a few species which form molecules above sunspots, and estimates derived from these sources lack the accuracy desired for comparison with meteoritic and planetary surface samples measured on the Earth. The solar wind spreads a sample of solar particles throughout the heliosphere, though the sample is very rarified: collecting a nanogram of oxygen, the third most abundant element, in a square centimeter cross section at the Earth's distance from the Sun takes five years. Nevertheless, foil collectors exposed to the solar wind for periods of hours on the surface of the Moon during the Apollo missions were used to determine the helium and neon solar-wind compositions sufficiently to show that the Earth's atmospheric neon was significantly evolved relative to the Sun. Spacecraft instruments developed subsequently have provided many insights into the composition of the solar wind, mostly in terms of elemental composition. These instruments have the advantage of observing a number of parameters simultaneously

Heat transference in flat solar collectors considering speed and wind direction; Transferencia de calor en colectores solares planos considerando velocidad y direccion del viento

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, M. C.; Rodriguez, P. A.; Salgado, R.; Venegas, M.; Lecuona, A.

2008-07-01

Thermal solar collector performance depends on the process temperature but also on environmental variables like solar radiation, ambient temperature, wind speed and wind direction. collector operating design parameters like insulating and optical characteristics will affect also its performance. An unsteady energy balance on the collector developing a numerical method has been carried out to evaluate thermal losses. The numerical results are validated with experimental data from the facility placed at UC3M. these data, together with environmental variables, enable to calculate experimentally the collector performance to be compared with normalization curve and model prediction. The latest ones adjust more accurately to experimental than those from normalization curve. The main causes for this discrepancy are optical degradation of the collector due to aging and the wind effects. (Author)

Wind/solar resource in Texas

Energy Technology Data Exchange (ETDEWEB)

Nelson, V.; Starcher, K.; Gaines, H. [West Texas A& M Univ., Canyon, TX (United States)

1997-12-31

Data are being collected at 17 sites to delineate a baseline for the wind and solar resource across Texas. Wind data are being collected at 10, 25, and 40 m (in some cases at 50 m) to determine wind shear and power at hub heights of large turbines. Many of the sites are located in areas of predicted terrain enhancement. The typical day in a month for power and wind turbine output was calculated for selected sites and combination of sites; distributed systems. Major result to date is that there is the possibility of load matching in South Texas during the summer months, even though the average values by month indicate a low wind potential.

Combined wind and solar feed-in to the grid

CSIR Research Space (South Africa)

Mushwana, Crescent

2018-05-01

Full Text Available This presentation highlights South African wind and solar resources and presents a case study on wind and solar PV combination. It also distinguishes between traditional and new philosophies regarding energy system design and the changes...

Solar-wind krypton and solid/gas fractionation in the early solar nebula

Science.gov (United States)

Wiens, Roger C.; Burnett, D. S.; Neugebauer, M.; Pepin, R. O.

1991-01-01

The solar-system Kr abundance is calculated from solar-wind noble-gas ratios, determined previously by low-temperature oxidations of lunar ilmenite grains, normalized to Si by spacecraft solar-wind measurements. The estimated Kr-83 abundance of 4.1 + or - 1.5 per million Si atoms is within uncertainty of estimates assuming no fractionation, determined from CI-chondrite abundances of surrounding elements. This is significant because it is the first such constraint on solid/gas fractionation, though the large uncertainty only confines it to somewhat less than a factor of two.

Identifying Wind and Solar Ramping Events: Preprint

Energy Technology Data Exchange (ETDEWEB)

Florita, A.; Hodge, B. M.; Orwig, K.

2013-01-01

Wind and solar power are playing an increasing role in the electrical grid, but their inherent power variability can augment uncertainties in power system operations. One solution to help mitigate the impacts and provide more flexibility is enhanced wind and solar power forecasting; however, its relative utility is also uncertain. Within the variability of solar and wind power, repercussions from large ramping events are of primary concern. At the same time, there is no clear definition of what constitutes a ramping event, with various criteria used in different operational areas. Here the Swinging Door Algorithm, originally used for data compression in trend logging, is applied to identify variable generation ramping events from historic operational data. The identification of ramps in a simple and automated fashion is a critical task that feeds into a larger work of 1) defining novel metrics for wind and solar power forecasting that attempt to capture the true impact of forecast errors on system operations and economics, and 2) informing various power system models in a data-driven manner for superior exploratory simulation research. Both allow inference on sensitivities and meaningful correlations, as well as the ability to quantify the value of probabilistic approaches for future use in practice.

The Solar Wind as a Turbulence Laboratory

Directory of Open Access Journals (Sweden)

Vincenzo Carbone

2013-05-01

Full Text Available In this review we will focus on a topic of fundamental importance for both astrophysics and plasma physics, namely the occurrence of large-amplitude low-frequency fluctuations of the fields that describe the plasma state. This subject will be treated within the context of the expanding solar wind and the most meaningful advances in this research field will be reported emphasizing the results obtained in the past decade or so. As a matter of fact, Helios inner heliosphere and Ulysses' high latitude observations, recent multi-spacecrafts measurements in the solar wind (Cluster four satellites and new numerical approaches to the problem, based on the dynamics of complex systems, brought new important insights which helped to better understand how turbulent fluctuations behave in the solar wind. In particular, numerical simulations within the realm of magnetohydrodynamic (MHD turbulence theory unraveled what kind of physical mechanisms are at the basis of turbulence generation and energy transfer across the spectral domain of the fluctuations. In other words, the advances reached in these past years in the investigation of solar wind turbulence now offer a rather complete picture of the phenomenological aspect of the problem to be tentatively presented in a rather organic way.

The solar wind in time: a change in the behaviour of older winds?

Science.gov (United States)

O'Fionnagáin, D.; Vidotto, A. A.

2018-05-01

In this paper, we model the wind of solar analogues at different ages to investigate the evolution of the solar wind. Recently, it has been suggested that winds of solar type stars might undergo a change in properties at old ages, whereby stars older than the Sun would be less efficient in carrying away angular momentum than what was traditionally believed. Adding to this, recent observations suggest that old solar-type stars show a break in coronal properties, with a steeper decay in X-ray luminosities and temperatures at older ages. We use these X-ray observations to constrain the thermal acceleration of winds of solar analogues. Our sample is based on the stars from the `Sun in Time' project with ages between 120 and 7000 Myr. The break in X-ray properties leads to a break in wind mass-loss rates (\\dot{M}) at roughly 2 Gyr, with \\dot{M} (t 2 Gyr) ∝ t-3.9. This steep decay in \\dot{M} at older ages could be the reason why older stars are less efficient at carrying away angular momentum, which would explain the anomalously rapid rotation observed in older stars. We also show that none of the stars in our sample would have winds dense enough to produce thermal emission above 1-2 GHz, explaining why their radio emissions have not yet been detected. Combining our models with dynamo evolution models for the magnetic field of the Earth, we find that, at early ages (≈100 Myr), our Earth had a magnetosphere that was three or more times smaller than its current size.

ENERGY DISSIPATION PROCESSES IN SOLAR WIND TURBULENCE

Energy Technology Data Exchange (ETDEWEB)

Wang, Y.; Wei, F. S.; Feng, X. S.; Sun, T. R.; Zuo, P. B. [SIGMA Weather Group, State Key Laboratory for Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Xu, X. J. [Space Science Institute, Macau University of Science and Technology, Macao (China); Zhang, J., E-mail: yw@spaceweather.ac.cn [School of Physics, Astronomy and Computational Sciences, George Mason University, 4400 University Drive, MSN 3F3, Fairfax, Virginia 22030 (United States)

2015-12-15

Turbulence is a chaotic flow regime filled by irregular flows. The dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, dissipation ultimately cannot be achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection (MR) are two possible dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the dissipation region scaling around a solar wind MR region. We find that the MR region shows unique multifractal scaling in the dissipation range, while the ambient solar wind turbulence reveals a monofractal dissipation process for most of the time. These results provide the first observational evidences for intermittent multifractal dissipation region scaling around a MR site, and they also have significant implications for the fundamental energy dissipation process.

Magnetosheath Propagation Time of Solar Wind Directional Discontinuities

Science.gov (United States)

Samsonov, A. A.; Sibeck, D. G.; Dmitrieva, N. P.; Semenov, V. S.; Slivka, K. Yu.; Å afránkova, J.; Němeček, Z.

2018-05-01

Observed delays in the ground response to solar wind directional discontinuities have been explained as the result of larger than expected magnetosheath propagation times. Recently, Samsonov et al. (2017, https://doi.org/10.1002/2017GL075020) showed that the typical time for a southward interplanetary magnetic field (IMF) turning to propagate across the magnetosheath is 14 min. Here by using a combination of magnetohydrodynamic simulations, spacecraft observations, and analytic calculations, we study the dependence of the propagation time on solar wind parameters and near-magnetopause cutoff speed. Increases in the solar wind speed result in greater magnetosheath plasma flow velocities, decreases in the magnetosheath thickness and, as a result, decreases in the propagation time. Increases in the IMF strength result in increases in the magnetosheath thickness and increases in the propagation time. Both magnetohydrodynamic simulations and observations suggest that propagation times are slightly smaller for northward IMF turnings. Magnetosheath flow deceleration must be taken into account when predicting the arrival times of solar wind structures at the dayside magnetopause.

Theoretical contributions to solar wind research - a review

International Nuclear Information System (INIS)

Cuperman, S.

1977-01-01

The theoretical work on the solar wind phenomena done since 1958 can be divided into two main parts: Part I - development and refinement of Parker's initial macroscopic model, the emphasis being placed upon steady state, spherically symmetric flow and the identification of the structure-less background solar wind plasma with the low speed flow. It is in this part that much progress in understanding the solar wind phenomenon has been achieved; Part II - generalization of Parker's initial model such as to include microscopic (kinetic) aspects, temporal variations, deviations from spherically symmetric conditions, complex local magnetic configurations, etc. The last two aspects, in particular, have received considerable attention with the discovery of the coronal holes, their association with high-speed flows and the tentative identification of these flows with the structure-less background solar wind plasma. This review is confined to Part I, as defined above. However, for completeness, several important aspects connected with the subjects enumerated under Part II and which represent the objects of the most recent investigation are also briefly reviewed. (Auth.)

Building Space Heating with a Solar-Assisted Heat Pump Using Roof-Integrated Solar Collectors

Directory of Open Access Journals (Sweden)

Zhiyong Yang

2011-03-01

Full Text Available A solar assisted heat pump (SAHP system was designed by using a roof-integrated solar collector as the evaporator, and then it was demonstrated to provide space heating for a villa in Tianjin, China. A building energy simulation tool was used to predict the space heating load and a three dimensional theoretical model was established to analyze the heat collection performance of the solar roof collector. A floor radiant heating unit was used to decrease the energy demand. The measurement results during the winter test period show that the system can provide a comfortable living space in winter, when the room temperature averaged 18.9 °C. The average COP of the heat pump system is 2.97 and with a maximum around 4.16.

Latitudinal distribution of the solar wind properties in the low- and high-pressure regimes: Wind observations

Directory of Open Access Journals (Sweden)

C. Lacombe

Full Text Available The solar wind properties depend on λ, the heliomagnetic latitude with respect to the heliospheric current sheet (HCS, more than on the heliographic latitude. We analyse the wind properties observed by Wind at 1 AU during about 2.5 solar rotations in 1995, a period close to the last minimum of solar activity. To determine λ, we use a model of the HCS which we fit to the magnetic sector boundary crossings observed by Wind. We find that the solar wind properties mainly depend on the modulus |λ|. But they also depend on a local parameter, the total pressure (magnetic pressure plus electron and proton thermal pressure. Furthermore, whatever the total pressure, we observe that the plasma properties also depend on the time: the latitudinal gradients of the wind speed and of the proton temperature are not the same before and after the closest HCS crossing. This is a consequence of the dynamical stream interactions. In the low pressure wind, at low |λ|, we find a clear maximum of the density, a clear minimum of the wind speed and of the proton temperature, a weak minimum of the average magnetic field strength, a weak maximum of the average thermal pressure, and a weak maximum of the average β factor. This overdense sheet is embedded in a density halo. The latitudinal thickness is about 5^° for the overdense sheet, and 20^° for the density halo. The HCS is thus wrapped in an overdense sheet surrounded by a halo, even in the non-compressed solar wind. In the high-pressure wind, the plasma properties are less well ordered as functions of the latitude than in the low-pressure wind; the minimum of the average speed is seen before the HCS crossing. The latitudinal thickness of the high-pressure region is about 20^°. Our observations are qualitatively consistent with the numerical model of Pizzo for the deformation of the heliospheric current sheet and plasma sheet.

Key words: Interplanetary physics (solar wind

The Potential of hybrid solar-wind electricity generation in Ghana

International Nuclear Information System (INIS)

Tibiru, Ayirewura Vitus

2013-07-01

In this work the potential of harnessing electricity from solar and wind sources in Ghana is evaluated both quantitatively and qualitatively. In this regard solar, wind and other relevant data were collected (over a period of one year) from various parts of Ghana. Detailed assessment of the capacity or potential of power production from hybrid solar-wind sources is done with the use of empirical mathematical formulae and the PRO VITUS model incorporated in the 'ENERGY X' software. The various characteristics of wind, solar and available energy resources for the five locations over a one year period have been studied too. The annual mean wind speed at a height of 10 m above ground level for five locations namely Accra, Kumasi, Takoradi, Sunyani and Tamale are 2.38 ms"-"1 ± 0.05, 2.39 ms"-"1 ± 0.05, 2.38 ms"-"1 ± 0.06, 2.18 ms"-"1 ± 0.05 and 2.47 ± ms"-"1 respectively and their corresponding annual mean solar radiations are 228.71 Wm"-"2 ± 9.81, 187.69 Wm"-"2 ± 9.60, 236.58 Wm"-"2 ± 10.39, 200.99 Wm"-"2 ± 9.88 and 231.63 Wm"-"2 . Thus, the five sites hold potential for hybrid solar-wind energy exploitation. (au)

Velocity fluctuations in polar solar wind: a comparison between different solar cycles

Directory of Open Access Journals (Sweden)

B. Bavassano

2009-02-01

Full Text Available The polar solar wind is a fast, tenuous and steady flow that, with the exception of a relatively short phase around the Sun's activity maximum, fills the high-latitude heliosphere. The polar wind properties have been extensively investigated by Ulysses, the first spacecraft able to perform in-situ measurements in the high-latitude heliosphere. The out-of-ecliptic phases of Ulysses cover about seventeen years. This makes possible to study heliospheric properties at high latitudes in different solar cycles. In the present investigation we focus on hourly- to daily-scale fluctuations of the polar wind velocity. Though the polar wind is a quite uniform flow, fluctuations in its velocity do not appear negligible. A simple way to characterize wind velocity variations is that of performing a multi-scale statistical analysis of the wind velocity differences. Our analysis is based on the computation of velocity differences at different time lags and the evaluation of statistical quantities (mean, standard deviation, skewness, and kurtosis for the different ensembles. The results clearly show that, though differences exist in the three-dimensional structure of the heliosphere between the investigated solar cycles, the velocity fluctuations in the core of polar coronal holes exhibit essentially unchanged statistical properties.

Velocity fluctuations in polar solar wind: a comparison between different solar cycles

Directory of Open Access Journals (Sweden)

B. Bavassano

2009-02-01

Full Text Available The polar solar wind is a fast, tenuous and steady flow that, with the exception of a relatively short phase around the Sun's activity maximum, fills the high-latitude heliosphere. The polar wind properties have been extensively investigated by Ulysses, the first spacecraft able to perform in-situ measurements in the high-latitude heliosphere. The out-of-ecliptic phases of Ulysses cover about seventeen years. This makes possible to study heliospheric properties at high latitudes in different solar cycles. In the present investigation we focus on hourly- to daily-scale fluctuations of the polar wind velocity. Though the polar wind is a quite uniform flow, fluctuations in its velocity do not appear negligible. A simple way to characterize wind velocity variations is that of performing a multi-scale statistical analysis of the wind velocity differences. Our analysis is based on the computation of velocity differences at different time lags and the evaluation of statistical quantities (mean, standard deviation, skewness, and kurtosis for the different ensembles. The results clearly show that, though differences exist in the three-dimensional structure of the heliosphere between the investigated solar cycles, the velocity fluctuations in the core of polar coronal holes exhibit essentially unchanged statistical properties.

Solar radiation, phytoplankton pigments and the radiant heating of the equatorial Pacific warm pool

Science.gov (United States)

Siegel, David A.; Ohlmann, J. Carter; Washburn, Libe; Bidigare, Robert R.; Nosse, Craig T.; Fields, Erik; Zhou, Yimei

1995-01-01

Recent optical, physical, and biological oceanographic observations are used to assess the magnitude and variability of the penetrating flux of solar radiation through the mixed layer of the warm water pool (WWP) of the western equatorial Pacific Ocean. Typical values for the penetrative solar flux at the climatological mean mixed layer depth for the WWP (30 m) are approx. 23 W/sq m and are a large fraction of the climatological mean net air-sea heat flux (approx. 40 W/sq m). The penetrating solar flux can vary significantly on synoptic timescales. Following a sustained westerly wind burst in situ solar fluxes were reduced in response to a near tripling of mixed layer phytoplankton pigment concentrations. This results in a reduction in the penetrative flux at depth (5.6 W/sq m at 30 m) and corresponds to a biogeochemically mediated increase in the mixed layer radiant heating rate of 0.13 C per month. These observations demonstrate a significant role of biogeochemical processes on WWP thermal climate. We speculate that this biogeochemically mediated feedback process may play an important role in enhancing the rate at which the WWP climate system returns to normal conditions following a westerly wind burst event.

Fundamentals of Solar Heating. Correspondence Course.

Science.gov (United States)

Sheet Metal and Air Conditioning Contractors National Association, Vienna, VA.

This course is designed for the use of employees of the air conditioning industry, and offers supervised correspondence instruction about solar technology. The following aspects of applied solar technology are covered: solar heating and cooling, solar radiation, solar collectors, heat storage control devices and specialty items, sizing solar…

Solar-powered Rankine heat pump for heating and cooling

Science.gov (United States)

Rousseau, J.

1978-01-01

The design, operation and performance of a familyy of solar heating and cooling systems are discussed. The systems feature a reversible heat pump operating with R-11 as the working fluid and using a motor-driven centrifugal compressor. In the cooling mode, solar energy provides the heat source for a Rankine power loop. The system is operational with heat source temperatures ranging from 155 to 220 F; the estimated coefficient of performance is 0.7. In the heating mode, the vapor-cycle heat pump processes solar energy collected at low temperatures (40 to 80 F). The speed of the compressor can be adjusted so that the heat pump capacity matches the load, allowing a seasonal coefficient of performance of about 8 to be attained.

HEMISPHERIC ASYMMETRIES IN THE POLAR SOLAR WIND OBSERVED BY ULYSSES NEAR THE MINIMA OF SOLAR CYCLES 22 AND 23

Energy Technology Data Exchange (ETDEWEB)

Ebert, R. W.; Dayeh, M. A.; Desai, M. I.; McComas, D. J. [Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 (United States); Pogorelov, N. V. [Physics Department, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

2013-05-10

We examined solar wind plasma and interplanetary magnetic field (IMF) observations from Ulysses' first and third orbits to study hemispheric differences in the properties of the solar wind and IMF originating from the Sun's large polar coronal holes (PCHs) during the declining and minimum phase of solar cycles 22 and 23. We identified hemispheric asymmetries in several parameters, most notably {approx}15%-30% south-to-north differences in averages for the solar wind density, mass flux, dynamic pressure, and energy flux and the radial and total IMF magnitudes. These differences were driven by relatively larger, more variable solar wind density and radial IMF between {approx}36 Degree-Sign S-60 Degree-Sign S during the declining phase of solar cycles 22 and 23. These observations indicate either a hemispheric asymmetry in the PCH output during the declining and minimum phase of solar cycles 22 and 23 with the southern hemisphere being more active than its northern counterpart, or a solar cycle effect where the PCH output in both hemispheres is enhanced during periods of higher solar activity. We also report a strong linear correlation between these solar wind and IMF parameters, including the periods of enhanced PCH output, that highlight the connection between the solar wind mass and energy output and the Sun's magnetic field. That these enhancements were not matched by similar sized variations in solar wind speed points to the mass and energy responsible for these increases being added to the solar wind while its flow was subsonic.

HEMISPHERIC ASYMMETRIES IN THE POLAR SOLAR WIND OBSERVED BY ULYSSES NEAR THE MINIMA OF SOLAR CYCLES 22 AND 23

International Nuclear Information System (INIS)

Ebert, R. W.; Dayeh, M. A.; Desai, M. I.; McComas, D. J.; Pogorelov, N. V.

2013-01-01

We examined solar wind plasma and interplanetary magnetic field (IMF) observations from Ulysses' first and third orbits to study hemispheric differences in the properties of the solar wind and IMF originating from the Sun's large polar coronal holes (PCHs) during the declining and minimum phase of solar cycles 22 and 23. We identified hemispheric asymmetries in several parameters, most notably ∼15%-30% south-to-north differences in averages for the solar wind density, mass flux, dynamic pressure, and energy flux and the radial and total IMF magnitudes. These differences were driven by relatively larger, more variable solar wind density and radial IMF between ∼36°S-60°S during the declining phase of solar cycles 22 and 23. These observations indicate either a hemispheric asymmetry in the PCH output during the declining and minimum phase of solar cycles 22 and 23 with the southern hemisphere being more active than its northern counterpart, or a solar cycle effect where the PCH output in both hemispheres is enhanced during periods of higher solar activity. We also report a strong linear correlation between these solar wind and IMF parameters, including the periods of enhanced PCH output, that highlight the connection between the solar wind mass and energy output and the Sun's magnetic field. That these enhancements were not matched by similar sized variations in solar wind speed points to the mass and energy responsible for these increases being added to the solar wind while its flow was subsonic.

A Deeper Understanding of Stability in the Solar Wind: Applying Nyquist's Instability Criterion to Wind Faraday Cup Data

Science.gov (United States)

Alterman, B. L.; Klein, K. G.; Verscharen, D.; Stevens, M. L.; Kasper, J. C.

2017-12-01

Long duration, in situ data sets enable large-scale statistical analysis of free-energy-driven instabilities in the solar wind. The plasma beta and temperature anisotropy plane provides a well-defined parameter space in which a single-fluid plasma's stability can be represented. Because this reduced parameter space can only represent instability thresholds due to the free energy of one ion species - typically the bulk protons - the true impact of instabilities on the solar wind is under estimated. Nyquist's instability criterion allows us to systematically account for other sources of free energy including beams, drifts, and additional temperature anisotropies. Utilizing over 20 years of Wind Faraday cup and magnetic field observations, we have resolved the bulk parameters for three ion populations: the bulk protons, beam protons, and alpha particles. Applying Nyquist's criterion, we calculate the number of linearly growing modes supported by each spectrum and provide a more nuanced consideration of solar wind stability. Using collisional age measurements, we predict the stability of the solar wind close to the sun. Accounting for the free-energy from the three most common ion populations in the solar wind, our approach provides a more complete characterization of solar wind stability.

Whistler mode waves and the electron heat flux in the solar wind: Cluster observations

Czech Academy of Sciences Publication Activity Database

Lacombe, C.; Alexandrova, O.; Matteini, L.; Santolík, Ondřej; Cornilleau-Wehrlin, N.; Mangeney, A.; De Conchy, Y.; Maksimovic, M.

2014-01-01

Roč. 796, č. 1 (2014), s. 1-11 ISSN 0004-637X R&D Projects: GA ČR GAP205/10/2279; GA MŠk LH12231 Institutional support: RVO:68378289 Keywords : solar wind * turbulence * waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 5.993, year: 2014 http://iopscience.iop.org/0004-637X/796/1/5/article

The solar wind neon abundance observed with ACE/SWICS and ULYSSES/SWICS

International Nuclear Information System (INIS)

Shearer, Paul; Raines, Jim M.; Lepri, Susan T.; Thomas, Jonathan W.; Gilbert, Jason A.; Landi, Enrico; Zurbuchen, Thomas H.; Von Steiger, Rudolf

2014-01-01

Using in situ ion spectrometry data from ACE/SWICS, we determine the solar wind Ne/O elemental abundance ratio and examine its dependence on wind speed and evolution with the solar cycle. We find that Ne/O is inversely correlated with wind speed, is nearly constant in the fast wind, and correlates strongly with solar activity in the slow wind. In fast wind streams with speeds above 600 km s –1 , we find Ne/O = 0.10 ± 0.02, in good agreement with the extensive polar observations by Ulysses/SWICS. In slow wind streams with speeds below 400 km s –1 , Ne/O ranges from a low of 0.12 ± 0.02 at solar maximum to a high of 0.17 ± 0.03 at solar minimum. These measurements place new and significant empirical constraints on the fractionation mechanisms governing solar wind composition and have implications for the coronal and photospheric abundances of neon and oxygen. The results are made possible by a new data analysis method that robustly identifies rare elements in the measured ion spectra. The method is also applied to Ulysses/SWICS data, which confirms the ACE observations and extends our view of solar wind neon into the three-dimensional heliosphere.

The solar wind neon abundance observed with ACE/SWICS and ULYSSES/SWICS

Energy Technology Data Exchange (ETDEWEB)

Shearer, Paul; Raines, Jim M.; Lepri, Susan T.; Thomas, Jonathan W.; Gilbert, Jason A.; Landi, Enrico; Zurbuchen, Thomas H. [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Von Steiger, Rudolf [International Space Science Institute, Hallerstrasse 6, CH-3012 Bern (Switzerland)

2014-07-01

Using in situ ion spectrometry data from ACE/SWICS, we determine the solar wind Ne/O elemental abundance ratio and examine its dependence on wind speed and evolution with the solar cycle. We find that Ne/O is inversely correlated with wind speed, is nearly constant in the fast wind, and correlates strongly with solar activity in the slow wind. In fast wind streams with speeds above 600 km s{sup –1}, we find Ne/O = 0.10 ± 0.02, in good agreement with the extensive polar observations by Ulysses/SWICS. In slow wind streams with speeds below 400 km s{sup –1}, Ne/O ranges from a low of 0.12 ± 0.02 at solar maximum to a high of 0.17 ± 0.03 at solar minimum. These measurements place new and significant empirical constraints on the fractionation mechanisms governing solar wind composition and have implications for the coronal and photospheric abundances of neon and oxygen. The results are made possible by a new data analysis method that robustly identifies rare elements in the measured ion spectra. The method is also applied to Ulysses/SWICS data, which confirms the ACE observations and extends our view of solar wind neon into the three-dimensional heliosphere.

Emerging large-scale solar heating applications

International Nuclear Information System (INIS)

Wong, W.P.; McClung, J.L.

2009-01-01

Currently the market for solar heating applications in Canada is dominated by outdoor swimming pool heating, make-up air pre-heating and domestic water heating in homes, commercial and institutional buildings. All of these involve relatively small systems, except for a few air pre-heating systems on very large buildings. Together these applications make up well over 90% of the solar thermal collectors installed in Canada during 2007. These three applications, along with the recent re-emergence of large-scale concentrated solar thermal for generating electricity, also dominate the world markets. This paper examines some emerging markets for large scale solar heating applications, with a focus on the Canadian climate and market. (author)

Emerging large-scale solar heating applications

Energy Technology Data Exchange (ETDEWEB)

Wong, W.P.; McClung, J.L. [Science Applications International Corporation (SAIC Canada), Ottawa, Ontario (Canada)

2009-07-01

Currently the market for solar heating applications in Canada is dominated by outdoor swimming pool heating, make-up air pre-heating and domestic water heating in homes, commercial and institutional buildings. All of these involve relatively small systems, except for a few air pre-heating systems on very large buildings. Together these applications make up well over 90% of the solar thermal collectors installed in Canada during 2007. These three applications, along with the recent re-emergence of large-scale concentrated solar thermal for generating electricity, also dominate the world markets. This paper examines some emerging markets for large scale solar heating applications, with a focus on the Canadian climate and market. (author)

The Yaglom law in the expanding solar wind

International Nuclear Information System (INIS)

Gogoberidze, G.; Perri, S.; Carbone, V.

2013-01-01

We study the Yaglom law, which relates the mixed third-order structure function to the average dissipation rate of turbulence, in a uniformly expanding solar wind by using the two-scale expansion model of magnetohydrodynamic (MHD) turbulence. We show that due to the expansion of the solar wind, two new terms appear in the Yaglom law. The first term is related to the decay of the turbulent energy by nonlinear interactions, whereas the second term is related to the non-zero cross-correlation of the Elsässer fields. Using magnetic field and plasma data from WIND and Helios 2 spacecrafts, we show that at lower frequencies in the inertial range of MHD turbulence the new terms become comparable to Yaglom's third-order mixed moment, and therefore they cannot be neglected in the evaluation of the energy cascade rate in the solar wind.

On Lunar Exospheric Column Densities and Solar Wind Access Beyond the Terminator from ROSAT Soft X-Ray Observations of Solar Wind Charge Exchange

Science.gov (United States)

Collier, Michael R.; Snowden, S. L.; Sarantos, M.; Benna, M.; Carter, J. A.; Cravens, T. E.; Farrell, W. M.; Fatemi, S.; Hills, H. Kent; Hodges, R. R.;

AUTOMATIC DETECTION ALGORITHM OF DYNAMIC PRESSURE PULSES IN THE SOLAR WIND

International Nuclear Information System (INIS)

Zuo, Pingbing; Feng, Xueshang; Wang, Yi; Xie, Yanqiong; Li, Huijun; Xu, Xiaojun

2015-01-01

Dynamic pressure pulses (DPPs) in the solar wind are a significant phenomenon closely related to the solar-terrestrial connection and physical processes of solar wind dynamics. In order to automatically identify DPPs from solar wind measurements, we develop a procedure with a three-step detection algorithm that is able to rapidly select DPPs from the plasma data stream and simultaneously define the transition region where large dynamic pressure variations occur and demarcate the upstream and downstream region by selecting the relatively quiet status before and after the abrupt change in dynamic pressure. To demonstrate the usefulness, efficiency, and accuracy of this procedure, we have applied it to the Wind observations from 1996 to 2008 by successfully obtaining the DPPs. The procedure can also be applied to other solar wind spacecraft observation data sets with different time resolutions

Large Scale Solar Heating

DEFF Research Database (Denmark)

Heller, Alfred

2001-01-01

The main objective of the research was to evaluate large-scale solar heating connected to district heating (CSDHP), to build up a simulation tool and to demonstrate the application of the simulation tool for design studies and on a local energy planning case. The evaluation was mainly carried out...... model is designed and validated on the Marstal case. Applying the Danish Reference Year, a design tool is presented. The simulation tool is used for proposals for application of alternative designs, including high-performance solar collector types (trough solar collectors, vaccum pipe collectors......). Simulation programs are proposed as control supporting tool for daily operation and performance prediction of central solar heating plants. Finaly the CSHP technolgy is put into persepctive with respect to alternatives and a short discussion on the barries and breakthrough of the technology are given....

Wind tunnel and CFD modelling of wind pressures on solar energy systems on flat roofs

NARCIS (Netherlands)

Bronkhorst, A.J.; Franke, J.; Geurts, C.P.W.; Bentum, van C.A.; Grepinet, F.

2010-01-01

Design of solar energy mounting systems requires more knowledge on the wind patterns around these systems. To obtain more insight in the flow patterns, which cause the pressure distributions on the solar energy systems, a wind tunnel test and Computational Fluid Dynamics analysis have been

A comparison of the heat and mechanical energy of a heat-pump wind turbine system

Energy Technology Data Exchange (ETDEWEB)

Aybek, A.; Arslan, S.; Yildiz, E.; Atik, K. [University of Kahramanmaras (Turkey). Dept. of Agricultural Machinery

2000-07-01

While a variety of applications of wind energy have been studied in Turkey, no significant efforts have been made to utilize heat pumps for heat generation. The use of heat pumps in wind energy systems is worth considering because of the high efficiency of heat production. In this study, a directly coupled wind turbine-heat pump system was designed, constructed, and tested. Measurements determined the mechanical energy of the rotors of the wind turbine and the heat energy generated by the heat pump driven by the rotor shaft. Based on the comparisons between the power generated by the heat pump and the power of the Savonius rotors, it was found that the heat energy gained by the heat pump was four times greater than the mechanical energy obtained from the turbine. It was suggested that heat pumps could be efficiently used in wind energy systems. (Author)

Wind loads on solar energy roofs

NARCIS (Netherlands)

Geurts, C.P.W.; Bentum, C.A. van

2007-01-01

This paper presents an overview of the wind loads on roofs, equipped with solar energy products, so called Active Roofs. Values given in this paper have been based on wind tunnel and full scale measurements, carried out at TNO, and on an interpretation of existing rules and guidelines. The results

Solar wind power electric plant on Vis (Croatia)

International Nuclear Information System (INIS)

1998-01-01

A project of a solar photovoltaic electric power plant presented by the Republic of Croatia at the meeting of the E.P.I.A. Mission for photovoltaic technology of the Mediterranean countries, aroused a great interest of the representatives of the invited countries. However, the interest within Croatia in the project has disappeared although E.P.I.A. offered a financing of two thirds of costs. There are attempts to construct 1800 kw wind-driven generators at the same location not taking into consideration a possibility of building a hybrid solar-wind-power electric plant. The chance that the solar part is completely of domestic origin is not accepted but the preference is given to the building of imported wind-driven generators. (orig.)

INERTIAL RANGE TURBULENCE OF FAST AND SLOW SOLAR WIND AT 0.72 AU AND SOLAR MINIMUM

Energy Technology Data Exchange (ETDEWEB)

Teodorescu, Eliza; Echim, Marius; Munteanu, Costel [Institute for Space Sciences, Măgurele (Romania); Zhang, Tielong [Space Research Institute, Graz (Austria); Bruno, Roberto [INAF-IAPS, Istituto di Astrofizica e Planetologia Spaziali, Rome (Italy); Kovacs, Peter, E-mail: eliteo@spacescience.ro [Geological and Geophysical Institute of Hungary, Budapest (Hungary)

2015-05-10

We investigate Venus Express observations of magnetic field fluctuations performed systematically in the solar wind at 0.72 Astronomical Units (AU), between 2007 and 2009, during the deep minimum of solar cycle 24. The power spectral densities (PSDs) of the magnetic field components have been computed for time intervals that satisfy the data integrity criteria and have been grouped according to the type of wind, fast and slow, defined for speeds larger and smaller, respectively, than 450 km s{sup −1}. The PSDs show higher levels of power for the fast wind than for the slow. The spectral slopes estimated for all PSDs in the frequency range 0.005–0.1 Hz exhibit a normal distribution. The average value of the trace of the spectral matrix is −1.60 for fast solar wind and −1.65 for slow wind. Compared to the corresponding average slopes at 1 AU, the PSDs are shallower at 0.72 AU for slow wind conditions suggesting a steepening of the solar wind spectra between Venus and Earth. No significant time variation trend is observed for the spectral behavior of both the slow and fast wind.

The Character of the Solar Wind, Surface Interactions, and Water

Science.gov (United States)

Farrell, William M.

2011-01-01

We discuss the key characteristics of the proton-rich solar wind and describe how it may interact with the lunar surface. We suggest that solar wind can be both a source and loss of water/OH related volatiles, and review models showing both possibilities. Energy from the Sun in the form of radiation and solar wind plasma are in constant interaction with the lunar surface. As such, there is a solar-lunar energy connection, where solar energy and matter are continually bombarding the lunar surface, acting at the largest scale to erode the surface at 0.2 Angstroms per year via ion sputtering [1]. Figure 1 illustrates this dynamically Sun-Moon system.

Solar heating - a major source of renewable energy

International Nuclear Information System (INIS)

Bosselaar, L.

2001-01-01

Actions that can be taken to increase the uptake of technology for solar water heaters and solar buildings are discussed. An overview of existing technology covers solar water heating, solar buildings, space heating, solar cooling, solar drying, solar desalination. Solar water heating, solar buildings and solar crop drying are discussed individually under the sub-headings of (a) the technology; (b) the market; (c) potential; (d) economics and (e) market acceleration strategies. Other subjects discussed are market acceleration, main opportunities, R and D needs and conclusions. The IEA solar heating and solar cooling programme is described

INJECTION OF PLASMA INTO THE NASCENT SOLAR WIND VIA RECONNECTION DRIVEN BY SUPERGRANULAR ADVECTION

International Nuclear Information System (INIS)

Yang Liping; He Jiansen; Tu Chuanyi; Chen Wenlei; Zhang Lei; Wang Linghua; Yan Limei; Peter, Hardi; Marsch, Eckart; Feng, Xueshang

2013-01-01

To understand the origin of the solar wind is one of the key research topics in modern solar and heliospheric physics. Previous solar wind models assumed that plasma flows outward along a steady magnetic flux tube that reaches continuously from the photosphere through the chromosphere into the corona. Inspired by more recent comprehensive observations, Tu et al. suggested a new scenario for the origin of the solar wind, in which it flows out in a magnetically open coronal funnel and mass is provided to the funnel by small-scale side loops. Thus mass is supplied by means of magnetic reconnection that is driven by supergranular convection. To validate this scenario and simulate the processes involved, a 2.5 dimensional (2.5D) numerical MHD model is established in the present paper. In our simulation a closed loop moves toward an open funnel, which has opposite polarity and is located at the edge of a supergranulation cell, and magnetic reconnection is triggered and continues while gradually opening up one half of the closed loop. Its other half connects with the root of the open funnel and forms a new closed loop which is submerged by a reconnection plasma stream flowing downward. Thus we find that the outflowing plasma in the newly reconnected funnel originates not only from the upward reconnection flow but also from the high-pressure leg of the originally closed loop. This implies an efficient supply of mass from the dense loop to the dilute funnel. The mass flux of the outflow released from the funnel considered in our study is calculated to be appropriate for providing the mass flux at the coronal base of the solar wind, though additional heating and acceleration mechanisms are necessary to keep the velocity at the higher location. Our numerical model demonstrates that in the funnel the mass for the solar wind may be supplied from adjacent closed loops via magnetic reconnection as well as directly from the footpoints of open funnels.

LONG-TERM TRENDS IN THE SOLAR WIND PROTON MEASUREMENTS

Energy Technology Data Exchange (ETDEWEB)

Elliott, Heather A.; McComas, David J. [Southwest Research Institute, San Antonio, TX (United States); DeForest, Craig E. [Southwest Research Institute, Boulder, CO (United States)

2016-11-20

We examine the long-term time evolution (1965–2015) of the relationships between solar wind proton temperature ( T {sub p}) and speed ( V {sub p}) and between the proton density ( n {sub p}) and speed using OMNI solar wind observations taken near Earth. We find a long-term decrease in the proton temperature–speed ( T {sub p}– V {sub p}) slope that lasted from 1972 to 2010, but has been trending upward since 2010. Since the solar wind proton density–speed ( n {sub p}– V {sub p}) relationship is not linear like the T {sub p}– V {sub p} relationship, we perform power-law fits for n {sub p}– V {sub p}. The exponent (steepness in the n {sub p}– V {sub p} relationship) is correlated with the solar cycle. This exponent has a stronger correlation with current sheet tilt angle than with sunspot number because the sunspot number maxima vary considerably from cycle to cycle and the tilt angle maxima do not. To understand this finding, we examined the average n {sub p} for different speed ranges, and found that for the slow wind n {sub p} is highly correlated with the sunspot number, with a lag of approximately four years. The fast wind n {sub p} variation was less, but in phase with the cycle. This phase difference may contribute to the n {sub p}– V {sub p} exponent correlation with the solar cycle. These long-term trends are important since empirical formulas based on fits to T {sub p} and V {sub p} data are commonly used to identify interplanetary coronal mass ejections, but these formulas do not include any time dependence. Changes in the solar wind density over a solar cycle will create corresponding changes in the near-Earth space environment and the overall extent of the heliosphere.

Solar-wind interactions with the Moon: nature and composition of nitrogen compounds

International Nuclear Information System (INIS)

Mukherjee, N.R.

1981-01-01

The lunar atmosphere and magnetic field are very tenuous. The solar wind, therefore, interacts directly with the lunar surface material and the dominant nature of interaction is essentially complete absorption of solar-wind particles by the surface material resulting in no upstream bowshock, but a cavity downstream. The solar-wind nitrogen ion species induce and undergo a complex set of reactions with the elements of lunar material and the solar-wind-derived trapped elements. The nitrogen concentration indigeneous to the lunar surface material is practically nil. Therefore any nitrogen and nitrogen compounds found in the lunar surface material are due to the solar-wind implantation of nitrogen ions. The flux of the solar-wind nitrogen ion species is about 6 X 10 3 cm -2 s -1 . Since there is no evidence for accumulation of nitrogen species in the lunar surface material, the outflux of nitrogen species from the lunar material to the atmosphere is the same as the solar-wind nitrogen ion flux. The species of the outflux are primarily NO and NH 3 , and their respective concentrations in the near surface lunar atmosphere are found to be 327 and 295 cm -3 . (Auth.)

Cometary X-rays : solar wind charge exchange in cometary atmospheres

NARCIS (Netherlands)

Bodewits, Dennis

2007-01-01

The interaction of the solar wind with the planets and the interstellar medium is of key importance for the evolution of our solar system. The interaction with Earth's atmosphere is best known for the northern light. In case of Mars, the interaction with the solar wind might have lead to the erosion

The Solar Wind-Mars Interaction Boundaries in Three Dimensions

Science.gov (United States)

Gruesbeck, J.; Espley, J. R.; Connerney, J. E. P.; DiBraccio, G. A.; Soobiah, Y. I. J.

2017-12-01

The Martian magnetosphere is a product of the interaction of Mars with the interplanetary magnetic field and the supersonic solar wind. A bow shock forms upstream of the planet as the solar wind is diverted around the planet. Closer to the planet another boundary is located that separates the shock-heated solar wind plasma from the planetary plasma in the Martian magnetosphere. The Martian magnetosphere is induced by the pile-up of the interplanetary magnetic field. This induced magnetospheric boundary (IMB) has been referred to by different names, in part due to the observations available at the time. The location of these boundaries have been previously analyzed using data from Phobos 2, Mars Global Surveyor, and Mars Express resulting in models describing their average shapes. Observations of individual transitions demonstrate that it is a boundary with a finite thickness. The MAVEN spacecraft has been in orbit about Mars since November 2014 resulting in many encounters of the spacecraft with the boundaries. Using data from the Particle and Fields Package (PFP), we identify over 1000 bow shock crossings and over 4000 IMB crossings that we use to model the average locations. We model the boundaries as a 3-dimensional surface allowing observations of asymmetry. The average location of the bow shock and IMB lies further from the planet in the southern hemisphere, where stronger crustal fields are present. The MAVEN PFP dataset allows concurrent observations of the magnetic field and plasma environment to investigate the nature of the IMB and the relationship of the boundary to the different plasma signatures. Finally, we model the upstream and downstream encounters of the boundaries separately to produce shell models that quantify the finite thicknesses of the boundaries.

Solar heating systems for houses. A design handbook for solar combisystems

International Nuclear Information System (INIS)

Weiss, W.

2003-11-01

A handbook giving guidance on systems for providing combined solar space heating and solar water heating for houses has been produced by an international team. The guidance focuses on selection of the optimum combi-system for groups of single-family houses and multi-family houses. Standard classification and evaluation procedures are described. The book should be a valuable tool for building engineers, architects, solar manufacturers and installers of solar solar energy systems, and anyone interested in optimizing combined water and space heating solar systems

Heat generation by a wind turbine

Energy Technology Data Exchange (ETDEWEB)

Corten, G.P. [ECN Wind, Petten (Netherlands)

2001-01-01

It will be shown that an actuator disk operating in wind turbine mode extracts more energy from the fluid than can be transferred into useful energy. At the Lanchester-Betz limit the decrease of the kinetic energy in the wind is converted by 2 /3 into useful power and by 1 /3 into heat. Behind the wind turbine the outer flow and the flow that has passed the actuator disk will mix. In this process momentum is conserved but part of the kinetic energy will dissipate in heat via viscous shear. 7 refs.

Solar origins of solar wind properties during the cycle 23 solar minimum and rising phase of cycle 24

Science.gov (United States)

Luhmann, Janet G.; Petrie, Gordon; Riley, Pete

2012-01-01

The solar wind was originally envisioned using a simple dipolar corona/polar coronal hole sources picture, but modern observations and models, together with the recent unusual solar cycle minimum, have demonstrated the limitations of this picture. The solar surface fields in both polar and low-to-mid-latitude active region zones routinely produce coronal magnetic fields and related solar wind sources much more complex than a dipole. This makes low-to-mid latitude coronal holes and their associated streamer boundaries major contributors to what is observed in the ecliptic and affects the Earth. In this paper we use magnetogram-based coronal field models to describe the conditions that prevailed in the corona from the decline of cycle 23 into the rising phase of cycle 24. The results emphasize the need for adopting new views of what is ‘typical’ solar wind, even when the Sun is relatively inactive. PMID:25685422

Energy savings for solar heating systems; Solvarmeanlaegs energibesparelser

Energy Technology Data Exchange (ETDEWEB)

Furbo, S.; Fan, J.

2011-01-15

Energy savings for a number of new solar heating systems in one family houses have been determined by means of information on the energy consumption of the houses before and after installation of the solar heating systems. The investigated solar heating systems are marketed by Velux Danmark A/S, Sonnnenkraft Scandinavia A/S and Batec Solvarme A/S. Solar domestic hot water systems as well as solar combi systems are included in the investigations The houses have different auxiliary energy supply systems: Natural gas boilers, oil fired burners, electrical heating and district heating. Some of the houses have a second auxiliary energy supply system. The collector areas vary from 1.83 m{sup 2} to 9.28 m{sup 2}. Some of the solar heating systems are based on energy units with a new integrated natural gas boiler and a heat storage for the solar heating system. The existing energy systems in the houses are for most of the houses used as the auxiliary energy systems for the solar heating systems. The yearly energy savings for the houses where the only change is the installation of the solar heating system vary from 300 kWh per m{sup 2} solar collector to 1300 kWh per m{sup 2} solar collector. The average yearly energy savings is about 670 kWh per m{sup 2} solar collector for these solar heating systems. The energy savings per m{sup 2} solar collector are not influenced by the solar heating system type, the company marketing the system, the auxiliary energy supply system, the collector area, the collector tilt, the collector azimuth, the energy consumption of the house or the location of the house. The yearly energy savings for the houses with solar heating systems based on energy units including a new natural gas boiler vary from 790 kWh per m{sup 2} solar collector to 2090 kWh per m{sup 2} solar collector. The average yearly energy savings is about 1520 kWh per m{sup 2} solar collector for these solar heating systems. The energy savings per m{sup 2} solar collector for

Solar Wind Charge Exchange During Geomagnetic Storms

Science.gov (United States)

Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

2012-01-01

On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

Analysis of ISEE-3/ICE solar wind data

Science.gov (United States)

Coplan, Michael A.

1989-01-01

Under the grant that ended November 11, 1988 work was accomplished in a number of areas, as follows: (1) Analysis of solar wind data; (2) Analysis of Giacobini/Zinner encounter data; (3) Investigation of solar wind and magnetospheric electron velocity distributions; and (4) Experimental investigation of the electronic structure of clusters. Reprints and preprints of publications resulting from this work are included in the appendices.

Solar heating action plan; Solvarme handlingsplan

Energy Technology Data Exchange (ETDEWEB)

Nielsen, Jan Erik

2011-10-15

This solar action plan should be seen as a follow-up to the Danish Energy Agency's solar heating strategy from 2007, which showed great potential and opportunities for exploitation and use of solar heat in Denmark. In relation to the strategy from 2007, this action plan adjusted the distribution of solar heat from district heating plants and individual plants, but it is still the objective of this action plan to achieve the strategy's overall goal for 2030. With the implementation of the Action Plan in early 2012, it is estimated that in 2030 there will be about. 10 million m2 of solar collectors in operation, 8 million m2 for district heating and 2 million m2 for individual heating, equivalent to an installed capacity totaling 7 GW. The budget for actions in the Action Plan is about 80 million DKK annually over the next 5 years to initiate and ensure this development. (LN)

Technology Roadmaps: Solar Heating and Cooling

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-09-06

The solar heating and cooling (SHC) roadmap outlines a pathway for solar energy to supply almost one sixth (18 EJ) of the world's total energy use for both heating and cooling by 2050. This would save some 800 megatonnes of carbon dioxide (CO2) emissions per year; more than the total CO2 emissions in Germany in 2009. While solar heating and cooling today makes a modest contribution to world energy demand, the roadmap envisages that if concerted action is taken by governments and industry, solar energy could annually produce more than 16% of total final energy use for low temperature heat and nearly 17% for cooling. Given that global energy demand for heat represents almost half of the world's final energy use -- more than the combined global demand for electricity and transport -- solar heat can make a significant contribution in both tackling climate change and strengthening energy security.

Technology Roadmaps: Solar Heating and Cooling

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-07-01

The solar heating and cooling (SHC) roadmap outlines a pathway for solar energy to supply almost one sixth (18 EJ) of the world’s total energy use for both heating and cooling by 2050. This would save some 800 megatonnes of carbon dioxide (CO2) emissions per year; more than the total CO2 emissions in Germany in 2009. While solar heating and cooling today makes a modest contribution to world energy demand, the roadmap envisages that if concerted action is taken by governments and industry, solar energy could annually produce more than 16% of total final energy use for low temperature heat and nearly 17% for cooling. Given that global energy demand for heat represents almost half of the world’s final energy use – more than the combined global demand for electricity and transport – solar heat can make a significant contribution in both tackling climate change and strengthening energy security.

Distributed Wind Cost Reduction: Learning from Solar

Energy Technology Data Exchange (ETDEWEB)

Tegen, Suzanne

2016-02-23

The distributed wind energy industry can learn several lessons from the solar industry regarding reducing soft costs. Suzanne Tegen presented this overview at the 2016 Distributed Wind Energy Association Business Conference in Washington, D.C., on February 23, 2016.

Agua Caliente Wind/Solar Project at Whitewater Ranch

Energy Technology Data Exchange (ETDEWEB)

Hooks, Todd [Agua Caliente Band of Cahuilla Indians, Palm Springs, CA (United States); Stewart, Royce [Red Mountain Energy Partners, Sante Fe, NM (United States)

2014-12-16

Agua Caliente Band of Cahuilla Indians (ACBCI) was awarded a grant by the Department of Energy (DOE) to study the feasibility of a wind and/or solar renewable energy project at the Whitewater Ranch (WWR) property of ACBCI. Red Mountain Energy Partners (RMEP) was engaged to conduct the study. The ACBCI tribal lands in the Coachella Valley have very rich renewable energy resources. The tribe has undertaken several studies to more fully understand the options available to them if they were to move forward with one or more renewable energy projects. With respect to the resources, the WWR property clearly has excellent wind and solar resources. The DOE National Renewable Energy Laboratory (NREL) has continued to upgrade and refine their library of resource maps. The newer, more precise maps quantify the resources as among the best in the world. The wind and solar technology available for deployment is also being improved. Both are reducing their costs to the point of being at or below the costs of fossil fuels. Technologies for energy storage and microgrids are also improving quickly and present additional ways to increase the wind and/or solar energy retained for later use with the network management flexibility to provide power to the appropriate locations when needed. As a result, renewable resources continue to gain more market share. The transitioning to renewables as the major resources for power will take some time as the conversion is complex and can have negative impacts if not managed well. While the economics for wind and solar systems continue to improve, the robustness of the WWR site was validated by the repeated queries of developers to place wind and/or solar there. The robust resources and improving technologies portends toward WWR land as a renewable energy site. The business case, however, is not so clear, especially when the potential investment portfolio for ACBCI has several very beneficial and profitable alternatives.

Solar and wind exergy potentials for Mars

International Nuclear Information System (INIS)

Delgado-Bonal, Alfonso; Martín-Torres, F. Javier; Vázquez-Martín, Sandra; Zorzano, María-Paz

2016-01-01

The energy requirements of the planetary exploration spacecrafts constrain the lifetime of the missions, their mobility and capabilities, and the number of instruments onboard. They are limiting factors in planetary exploration. Several missions to the surface of Mars have proven the feasibility and success of solar panels as energy source. The analysis of the exergy efficiency of the solar radiation has been carried out successfully on Earth, however, to date, there is not an extensive research regarding the thermodynamic exergy efficiency of in-situ renewable energy sources on Mars. In this paper, we analyse the obtainable energy (exergy) from solar radiation under Martian conditions. For this analysis we have used the surface environmental variables on Mars measured in-situ by the Rover Environmental Monitoring Station onboard the Curiosity rover and from satellite by the Thermal Emission Spectrometer instrument onboard the Mars Global Surveyor satellite mission. We evaluate the exergy efficiency from solar radiation on a global spatial scale using orbital data for a Martian year; and in a one single location in Mars (the Gale crater) but with an appreciable temporal resolution (1 h). Also, we analyse the wind energy as an alternative source of energy for Mars exploration and compare the results with those obtained on Earth. We study the viability of solar and wind energy station for the future exploration of Mars, showing that a small square solar cell of 0.30 m length could maintain a meteorological station on Mars. We conclude that the low density of the atmosphere of Mars is responsible of the low thermal exergy efficiency of solar panels. It also makes the use of wind energy uneffective. Finally, we provide insights for the development of new solar cells on Mars. - Highlights: • We analyse the exergy of solar radiation under Martian environment • Real data from in-situ instruments is used to determine the maximum efficiency of radiation • Wind

Global solar magetic field organization in the extended corona: influence on the solar wind speed and density over the cycle.

Science.gov (United States)

Réville, V.; Velli, M.; Brun, S.

2017-12-01

The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11yr solar cycle. For instance, the wind terminal velocity is thought to be anti-correlated with the expansion factor, a measure of how the magnetic field varies with height in the solar corona, usually computed at a fixed height (≈ 2.5 Rȯ, the source surface radius which approximates the distance at which all magnetic field lines become open). However, the magnetic field expansion affects the solar wind in a more detailed way, its influence on the solar wind properties remaining significant well beyond the source surface: we demonstrate this using 3D global MHD simulations of the solar corona, constrained by surface magnetograms over half a solar cycle (1989-2001). For models to comply with the constraints provided by observed characteristics of the solar wind, namely, that the radial magnetic field intensity becomes latitude independent at some distance from the Sun (Ulysses observations beyond 1 AU), and that the terminal wind speed is anti-correlated with the mass flux, they must accurately describe expansion beyond the solar wind critical point (even up to 10Rȯ and higher in our model). We also show that near activity minimum, expansion in the higher corona beyond 2.5 Rȯ is actually the dominant process affecting the wind speed. We discuss the consequences of this result on the necessary acceleration profile of the solar wind, the location of the sonic point and of the energy deposition by Alfvén waves.

Study on the optium operation of the solar assisted air-source heat pump system. Part 5. ; Fundamental performance of a SOL-AIR PANEL effected by environmental condition that can be controlled artifically. SOL-AIR heat pump system no saiteki untenho ni kansuru kenkyu. 5. ; Jinko kankyo joken hendo ni uoru shuhonetsu panel no kiso tokusei

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Y; Ohashi, K; Kasuya, A [Kogauin Univ., Tokyo (Japan); Shiraishi, K; Hino, T [Kajima Institute of Construction Technology, Tokyo (Japan)

1990-12-06

This paper follows the privious paper which reports about the experimental system of the solar air panel and the experimental conditions in the artificial environmental room. In this paper the basic performance of heat exchange of a solar panel related to the difference of the artificial enviromental conditions such as the wind speed, the wind direction, the radiation, and the dry or wet surface of the solar air panel, and the results of its analysis are presented. As a result of the experiment, the following were determined: wind direction affects the heat exchange characteristics of the solar air panel; the slits lead to improved heat conduction on both sides of the panel; and when the flat surface of the panel is wet the amount of all the heat exchange increases, due to increased air circulation and evaporation. It is possible to estimate the total quantity of heat exchange, and to determine the fundamental performance of a solar air panel. 7 refs., 10 figs.

The most intense electric currents in turbulent high speed solar wind

Science.gov (United States)

Podesta, J. J.

2017-12-01

Theory and simulations suggest that dissipation of turbulent energy in collisionless astrophysical plasmas occurs most rapidly in spatial regions where the current density is most intense. To advance understanding of plasma heating by turbulent dissipation in the solar corona and solar wind, it is of interest to characterize the properties of plasma regions where the current density takes exceptionally large values and to identify the operative dissipation processes. In the solar wind, the curl of the magnetic field cannot be measured using data from a single spacecraft, however, a suitable proxy for this quantity can be constructed from the spatial derivative of the magnetic field along the flow direction of the plasma. This new approach is used to study the properties of the most intense current carrying structures in a high speed solar wind stream near 1 AU. In this study, based on 11 Hz magnetometer data from the WIND spacecraft, the spatial resolution of the proxy technique is approximately equal to the proton inertial length. Intense current sheets or current carrying structures were identified as events where the magnitude of the current density exceeds μ+5σ, where μ and σ are the mean and standard deviation of the magnitude of the current density (or its proxy), respectively. Statistical studies show (1) the average size of these 5σ events is close to the smallest resolvable scale in the data set, the proton inertial length; (2) the linear distance between neighboring events follows a power law distribution; and (3) the average peak current density of 5σ events is around 1 pA/cm2. The analysis techniques used in these studies have been validated using simulated spacecraft data from three dimensional hybrid simulations which show that results based on the analysis of the proxy are qualitatively and quantitatively similar to results based on the analysis of the true current density.

Solar Air Heaters with Thermal Heat Storages

OpenAIRE

Saxena, Abhishek; Goel, Varun

2013-01-01

Solar energy can be converted into different forms of energy, either to thermal energy or to electrical energy. Solar energy is converted directly into electrical power by photovoltaic modules, while solar collector converts solar energy into thermal energy. Solar collector works by absorbing the direct solar radiation and converting it into thermal energy, which can be stored in the form of sensible heat or latent heat or a combination of sensible and latent heats. A theoretical study has be...

Diamagnetic effect in the foremoon solar wind observed by Kaguya

Science.gov (United States)

Nishino, Masaki N.; Saito, Yoshifumi; Tsunakawa, Hideo; Miyake, Yohei; Harada, Yuki; Yokota, Shoichiro; Takahashi, Futoshi; Matsushima, Masaki; Shibuya, Hidetoshi; Shimizu, Hisayoshi

2017-04-01

Direct interaction between the lunar surface and incident solar wind is one of the crucial phenomena of the planetary plasma sciences. Recent observations by lunar orbiters revealed that strength of the interplanetary magnetic field (IMF) at spacecraft altitude often increases over crustal magnetic fields on the dayside. In addition, variations of the IMF on the lunar night side have been reported in the viewpoint of diamagnetic effect around the lunar wake. However, few studies have been performed for the IMF over non-magnetized regions on the dayside. Here we show an event where strength of the IMF decreases at 100 km altitude on the lunar dayside (i.e. in the foremoon solar wind) when the IMF is almost parallel to the incident solar wind flow, comparing the upstream solar wind data from ACE with Kaguya magnetometer data. The lunar surface below the Kaguya orbit is not magnetized (or very weakly magnetized), and the sunward-travelling protons show signatures of those back-scattered at the lunar surface. We find that the decrease in the magnetic pressure is compensated by the thermal pressure of the back-scattered protons. In other words, the IMF strength in the foremoon solar wind decreases by diamagnetic effect of sunward-travelling protons back-scattered at the lunar dayside surface. Such an effect would be prominent in the high-beta solar wind, and may be ubiquitous in the environment where planetary surface directly interacts with surrounding space plasma.

Interaction of intersteller pick-up ions with the solar wind

International Nuclear Information System (INIS)

Mobius, E.; Klecker, B.; Hovestadt, D.; Scholer, M.

1988-01-01

The interaction of interstellar pick-up ions with the solar wind is studied by comparing a model for the velocity distribution function of pick-up ions with actual measurements of He + ions in the solar wind. The model includes the effects of pitch-angle diffusion due to interplanetary Alfven waves, adiabatic deceleration in the expanding solar wind and the radial variation of the source function. It is demonstrated that the scattering mean free path is in the range ≤0.1 AU and that energy diffusion can be neglected as compared with adiabatic deceleration. The effects of adiabatic focusing, of the radial variation of the neutral density and of an variation of the solar wind velocity with distance from the Sun are investigated. With the correct choice of these parameters the authors can model the measured energy spectra of the pick-up ions does not vary with the solar wind velocity and the direction of the interplanetary magnetic field for a given local neutral gas density and ionization rate. Therefore, the comparison of the model distributions with the measurements leads to a quantitative determination of the local interstellar gas density

Estimated solar wind-implanted helium-3 distribution on the Moon

Science.gov (United States)

Johnson, J. R.; Swindle, T.D.; Lucey, P.G.

1999-01-01

Among the solar wind-implanted volatiles present in the lunar regolith, 3 He is possibly the most valuable resource because of its potential as a fusion fuel. The abundance of 3 He in the lunar regolith at a given location depends on surface maturity, the amount of solar wind fluence, and titanium content, because ilmenite (FeTiO3) retains helium much better than other major lunar minerals. Surface maturity and TiO2 maps from Clementine multispectral data sets are combined here with a solar wind fluence model to produce a 3He abundance map of the Moon. Comparison of the predicted 3He values to landing site observations shows good correlation. The highest 3He abundances occur in the farside maria (due to greater solar wind fluence received) and in higher TiO2 nearside mare regions.

Solar wind conditions for a quiet magnetosphere

International Nuclear Information System (INIS)

Kerns, K.J.; Gussenhoven, M.S.

1990-01-01

The conditions of the solar wind that lead to a quiet magnetosphere are determined under the assumption that the quiet or baseline magnetosphere can be identified by prolonged periods of low values of the am index. The authors analyzed solar wind data from 1978 to 1984 (7 years) during periods in which am ≤ 3 nT to identify those solar wind parameters that deviate significantly from average values. Parallel studies were also performed for prolonged periods of Kp = 0, 0+ and AE z ) show distinctive variations from average values. They independently varied these solar wind parameters and the length of time the conditions must persist to minimize am. This was done with the additional requirement that the conditions yield a reasonable number of occurrences (5% of the data set). The resulting baseline conditions are V ≤ 390 km/s; 180 degree - arctan |B y /B z | ≤ 101 degree, when b z ≤ 0 (no restriction on B z positive); B ≤ 6.5 nT; and persistence of these conditions for at least 5 hours. Minimizing the am index does not require a clear upper limit on the value of B z as might be anticipated from the work of Gussenhoven (1988) and Berthelier (1980). Apparently, this is a result of the requirement that the conditions must occur 5% of the time. When the requirement is lowered to 1% occurrence, an upper limit to B z emerges

Does the magnetic expansion factor (fs) play a role in solar wind acceleration?

Science.gov (United States)

Wallace, Samantha; Arge, Charles N.; Pihlstrom, Ylva

2017-08-01

For the past 25 years, magnetic expansion factor (fs) has been a key parameter used in the calculation of terminal solar wind speed (vsw) in both the Wang-Sheeley-Arge (WSA) model and its predecessor the Wang-Sheeley (WS) model. Since the discovery of an inverse relationship between fs and vsw, the physical role that magnetic expansion factor plays in the acceleration of the solar wind has been explored and debated. In this study, we investigate whether magnetic expansion factor plays a causal role in determining the terminal speed of the solar wind or merely serves as proxy. To do so, we explore how fs, as determined by WSA, relates to vsw for two different scenarios: 1) extended periods where the fast solar wind emerges from the centers of large coronal holes, and 2) periods where the solar wind emerges from pseudostreamers. For these same scenarios, we will also consider an alternative empirical relationship between solar wind speed and the minimum angular distance at the photosphere of a solar wind source to the nearest coronal hole boundary (i.e., DCHB, θb). We then compare these two different prediction techniques directly with heliospheric observations (i.e., ACE, STEREO-A & B, Ulysses) of solar wind speed to determine whether one clearly out performs the other.

The effect of asymmetric solar wind on the Lyman α sky background

International Nuclear Information System (INIS)

Joselyn, J.A.; Holzer, T.E.

1975-01-01

The Lyman α (Ly α) sky background arises from the scattering of solar Ly α from a spatial distribution of neutral hydrogen in interplanetary space. This distribution is partially determined by the solar wind proton flux, which provides the principal mechanism of loss by charge exchange of the neutral hydrogen. By generating isophotal maps of scattered Ly α for several choices of interstellar wind direction and solar wind proton flux distributions, the results show that latitudinal variations of the solar wind proton flux can have a significant effect on the observed location and shape of the Ly α intensity maximum. This fact should aid in the interpretation of Ly α maps and also indicates a possible method for inferring values for the average solar wind proton flux out of the ecliptic plane

Solar heating pipe

Energy Technology Data Exchange (ETDEWEB)

Hinson-Rider, G.

1977-10-04

A fluid carrying pipe is described having an integral transparent portion formed into a longitudinally extending cylindrical lens that focuses solar heat rays to a focal axis within the volume of the pipe. The pipe on the side opposite the lens has a heat ray absorbent coating for absorbing heat from light rays that pass through the focal axis.

Preferred solar wind emitting longitudes on the sun

International Nuclear Information System (INIS)

Gosling, J.T.; Asbridge, J.R.; Bame, S.J.; Feldman, W.C.

1977-01-01

During the 11 1/2-year period from July 1964 through December 1975, high- and low-speed solar wind flows originated from preferred solar longitudes. The preferred longitude effect was most pronounced from 1970 onward but was also evident in the years preceding 1970. The most pronounced modulation in average solar wind speed with longitude (approximately 20%) was obtained when it was assumed that the synodic rotation period of the sun is 27.025 days. Some deep internal structure in the sun must ultmately be responsible for these long-lived longitudinal effects, which appear to rotate rigidly with the sun

Cause of solar wind speed variations observed at 1 a.u

International Nuclear Information System (INIS)

Hakamada, K.; Akasofu, S.

1981-01-01

An attempt is made to interpret solar wind variations observed at the earth's distance, namely the solar cycle variations, the semi-annual variations, and the 27-day variations, as well as the polarity changes of the interplanetary magnetic field, mainly in terms of two effects, a positive latitudinal gradient of the solar wind speed and a wobbling solar dipole, combined with the annual (heliospheric) latitudinal excursion of the earth. It is shown that a significant part of the solar wind variations observed at the earth's distance and the changes of polarity pattern of the interplanetary magnetic field can be reasonably well reproduced by the two effects

Helium abundance and speed difference between helium ions and protons in the solar wind from coronal holes, active regions, and quiet Sun

Science.gov (United States)

Fu, Hui; Madjarska, M. S.; Li, Bo; Xia, LiDong; Huang, ZhengHua

2018-05-01

Two main models have been developed to explain the mechanisms of release, heating and acceleration of the nascent solar wind, the wave-turbulence-driven (WTD) models and reconnection-loop-opening (RLO) models, in which the plasma release processes are fundamentally different. Given that the statistical observational properties of helium ions produced in magnetically diverse solar regions could provide valuable information for the solar wind modelling, we examine the statistical properties of the helium abundance (AHe) and the speed difference between helium ions and protons (vαp) for coronal holes (CHs), active regions (ARs) and the quiet Sun (QS). We find bimodal distributions in the space of AHeand vαp/vA(where vA is the local Alfvén speed) for the solar wind as a whole. The CH wind measurements are concentrated at higher AHeand vαp/vAvalues with a smaller AHedistribution range, while the AR and QS wind is associated with lower AHeand vαp/vA, and a larger AHedistribution range. The magnetic diversity of the source regions and the physical processes related to it are possibly responsible for the different properties of AHeand vαp/vA. The statistical results suggest that the two solar wind generation mechanisms, WTD and RLO, work in parallel in all solar wind source regions. In CH regions WTD plays a major role, whereas the RLO mechanism is more important in AR and QS.

Potential for Development of Solar and Wind Resource in Bhutan

Energy Technology Data Exchange (ETDEWEB)

Gilman, P.; Cowlin, S.; Heimiller, D.

2009-09-01

With support from the U.S. Agency for International Development (USAID), the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) produced maps and data of the wind and solar resources in Bhutan. The solar resource data show that Bhutan has an adequate resource for flat-plate collectors, with annual average values of global horizontal solar radiation ranging from 4.0 to 5.5 kWh/m2-day (4.0 to 5.5 peak sun hours per day). The information provided in this report may be of use to energy planners in Bhutan involved in developing energy policy or planning wind and solar projects, and to energy analysts around the world interested in gaining an understanding of Bhutan's wind and solar energy potential.

Application of Power Systems Economics to Wind and Solar Power Integration

OpenAIRE

Mills, Andrew David

2015-01-01

The focus of this dissertation is the economic implications of the technical challenges of integrating variable generation, namely wind and solar, into the electric power system. The research is organized around three topics: short-term variability of wind and solar generation, changes in the economic value of wind and solar with increasing penetration, and the effectiveness of different measures at mitigating changes in economic value with increasing penetration levels. Early studies of PV g...

Fossil energy versus nuclear, wind, solar and agricultural biomass: Insights from an Italian national survey

International Nuclear Information System (INIS)

Cicia, Gianni; Cembalo, Luigi; Del Giudice, Teresa; Palladino, Andrea

2012-01-01

In Italy there has been considerable political debate around the new energy policy, which is specifically designed to contribute to climate change mitigation. While there is renewed interest in nuclear energy generation, there has been heated debate concerning wind farms that have rapidly expanded and are dramatically changing the landscape in many rural areas. Finally, interest has also increased in biomass as an energy source. However, in this case, a significant part of the population is worried about landscape change and primary crop reduction. In this study we report the results from a nation-wide survey (=504 households) in Italy undertaken during summer 2009. A Latent Class Choice Experiment was used to quantify household preferences over different energy sources. Our results show that Italian households can be split into three segments with homogeneous preferences. The first segment (35% of the population) shows strong preference for wind and solar energy and dislikes both biomass and nuclear. The second (33% of the population) shows moderate preference for solar and wind energy and, as with the first segment, dislikes both nuclear and biomass. The third (32% of the population) shows a strong preference for green energy (solar, wind and biomass) and is very much against nuclear energy. The three segments were also characterized in terms of household socio-economic characteristics. - Highlights: ► We quantify Italian household preferences over different energy sources. ► Results come from a nation-wide survey undertaken during summer 2009. ► Energy sources tested: fossil fuel, nuclear, wind, solar and agricultural biomass. ► A latent class choice experiment was used. ► Italians can be split into three segments with different energy source preferences.

Internal plasma state of the high speed solar wind at 1 AU

International Nuclear Information System (INIS)

Feldman, W.C.; Abraham--Shrauner, B.; Asbridge, J.R.; Bame, S.J.

1976-01-01

The character of particle velocity distributions in the high speed solar wind is presented. It is found that electron distribution shapes differ from simple bi-Maxwellians in that a hot, strongly beamed, high energy electron component is always present and is observed to move relative to a distinct low energy electron component along the magnetic field direction, B, away from the sun. The velocity difference between hot and cold electron components appears, at times, to be strongly correlated with the local Alfven speed. This correlation suggests that the solar wind heat flux is being limited some of the time in the neighborhood of 1 AU. Proton velocity distributions are also best described in terms of two relatively convecting, unresolved components. The velocity of the lower density proton beam component is generally larger than that of the main component and the temperature of the main component perpendicular to B is typically 2 to 3 times larger than its parallel temperature. Alpha particles as a whole generally move faster than the protons along B and have a temperature which is, on the average, 6 times higher than the temperature of the total proton population. Evidence is presented which supports the idea that the two-component proton structure observed in high speed regions is intimately related to fine scale velocity variations at 1 AU, and hence by inference, to prominent spatial and/or temporal structures present throughout that part of the corona from which the solar wind evolves

Ulysses solar wind plasma observations at high southerly latitudes.

Science.gov (United States)

Phillips, J L; Bame, S J; Feldman, W C; Gosling, J T; Hammond, C M; McComas, D J; Goldstein, B E; Neugebauer, M; Scime, E E; Suess, S T

1995-05-19

Solar wind plasma observations made by the Ulysses spacecraft through -80.2 degrees solar latitude and continuing equatorward to -40.1 degrees are summarized. Recurrent high-speed streams and corotating interaction regions dominated at middle latitudes. The speed of the solar wind was typically 700 to 800 kilometers per second poleward of -35 degrees . Corotating reverse shocks persisted farther south than did forward shocks because of the tilt of the heliomagnetic streamer belt. Sporadic coronal mass ejections were seen as far south as -60.5 degrees . Proton temperature was higher and the electron strahl was broader at higher latitudes. The high-latitude wind contained compressional, pressure-balanced, and Alfvénic structures.

Formation of Heliospheric Arcs of Slow Solar Wind

Energy Technology Data Exchange (ETDEWEB)

Higginson, A. K.; Zurbuchen, T. H. [Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Antiochos, S. K.; DeVore, C. R. [Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Wyper, P. F., E-mail: aleida@umich.edu [Department of Mathematical Sciences, Durham University, Durham DH1 3LE (United Kingdom)

2017-05-01

A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun’s atmosphere is divided into magnetically open regions, known as coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchange reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole with a geometry that includes a narrow corridor flanked by closed field and is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations.

Design of Hybrid Solar and Wind Energy Harvester for Fishing Boat

Science.gov (United States)

Banjarnahor, D. A.; Hanifan, M.; Budi, E. M.

2017-07-01

In southern beach of West Java, Indonesia, there are many villagers live as fishermen. They use small boats for fishing, in one to three days. Therefore, they need a fish preservation system. Fortunately, the area has high potential of solar and wind energy. This paper presents the design of a hybrid solar and wind energy harvester to power a refrigerator in the fishing boat. The refrigerator should keep the fish in 2 - 4 °C. The energy needed is 720 Wh daily. In the area, the daily average wind velocity is 4.27 m/s and the sun irradiation is 672 W/m2. The design combined two 100W solar panels and a 300W wind turbine. The testing showed that the solar panels can harvest 815 - 817 Wh of energy, while the wind turbine can harvest 43 - 62 Wh of energy daily. Therefore, the system can fulfil the energy requirement in fishing boat, although the solar panels were more dominant. To install the wind turbine on the fishing-boat, a computational design had been conducted. The boat hydrostatic dimension was measured to determine its stability condition. To reach a stable equilibrium condition, the wind turbine should be installed no more than 1.7 m of height.

CHARACTERIZATION OF TRANSITIONS IN THE SOLAR WIND PARAMETERS

International Nuclear Information System (INIS)

Perri, S.; Balogh, A.

2010-01-01

The distinction between fast and slow solar wind streams and the dynamically evolved interaction regions is reflected in the characteristic fluctuations of both the solar wind and the embedded magnetic field. High-resolution magnetic field data from the Ulysses spacecraft have been analyzed. The observations show rapid variations in the magnetic field components and in the magnetic field strength, suggesting a structured nature of the solar wind at small scales. The typical sizes of fluctuations cover a broad range. If translated to the solar surface, the scales span from the size of granules (∼10 3 km) and supergranules (∼10 4 km) on the Sun down to ∼10 2 km and less. The properties of the short time structures change in the different types of solar wind. While fluctuations in fast streams are more homogeneous, slow streams present a bursty behavior in the magnetic field variances, and the regions of transition are characterized by high levels of power in narrow structures around the transitions. The probability density functions of the magnetic field increments at several scales reveal a higher level of intermittency in the mixed streams, which is related to the presence of well localized features. It is concluded that, apart from the differences in the nature of fluctuations in flows of different coronal origin, there is a small-scale structuring that depends on the origin of streams themselves but it is also related to a bursty generation of the fluctuations.

A hybrid reconfigurable solar and wind energy system

Science.gov (United States)

Gadkari, Sagar A.

We study the feasibility of a novel hybrid solar-wind hybrid system that shares most of its infrastructure and components. During periods of clear sunny days the system will generate electricity from the sun using a parabolic concentrator. The concentrator is formed by individual mirror elements and focuses the light onto high intensity vertical multi-junction (VMJ) cells. During periods of high wind speeds and at night, the same concentrator setup will be reconfigured to channel the wind into a wind turbine which will be used to harness wind energy. In this study we report on the feasibility of this type of solar/wind hybrid energy system. The key mechanisms; optics, cooling mechanism of VMJ cells and air flow through the system were investigated using simulation tools. The results from these simulations, along with a simple economic analysis giving the levelized cost of energy for such a system are presented. An iterative method of design refinement based on the simulation results was used to work towards a prototype design. The levelized cost of the system achieved in the economic analysis shows the system to be a good alternative for a grid isolated site and could be used as a standalone system in regions of lower demand. The new approach to solar wind hybrid system reported herein will pave way for newer generation of hybrid systems that share common infrastructure in addition to the storage and distribution of energy.

Solar Wind Associated with Near Equatorial Coronal Hole M ...

Indian Academy of Sciences (India)

2015-05-25

May 25, 2015 ... coronal hole and solar wind. For both the wavelength bands, we also com- pute coronal hole radiative energy near the earth and it is found to be of similar order as that of solar wind energy. However, for the wavelength. 193 Å, owing to almost similar magnitudes of energy emitted by coronal hole and ...

Contribution of Strong Discontinuities to the Power Spectrum of the Solar Wind

International Nuclear Information System (INIS)

Borovsky, Joseph E.

2010-01-01

Eight and a half years of magnetic field measurements (2 22 samples) from the ACE spacecraft in the solar wind at 1 A.U. are analyzed. Strong (large-rotation-angle) discontinuities in the solar wind are collected and measured. An artificial time series is created that preserves the timing and amplitudes of the discontinuities. The power spectral density of the discontinuity series is calculated and compared with the power spectral density of the solar-wind magnetic field. The strong discontinuities produce a power-law spectrum in the ''inertial subrange'' with a spectral index near the Kolmogorov -5/3 index. The discontinuity spectrum contains about half of the power of the full solar-wind magnetic field over this ''inertial subrange.'' Warnings are issued about the significant contribution of discontinuities to the spectrum of the solar wind, complicating interpretation of spectral power and spectral indices.

An analytical investigation: Effect of solar wind on lunar photoelectron sheath

Science.gov (United States)

Mishra, S. K.; Misra, Shikha

2018-02-01

The formation of a photoelectron sheath over the lunar surface and subsequent dust levitation, under the influence of solar wind plasma and continuous solar radiation, has been analytically investigated. The photoelectron sheath characteristics have been evaluated using the Poisson equation configured with population density contributions from half Fermi-Dirac distribution of the photoemitted electrons and simplified Maxwellian statistics of solar wind plasma; as a consequence, altitude profiles for electric potential, electric field, and population density within the photoelectron sheath have been derived. The expression for the accretion rate of sheath electrons over the levitated spherical particles using anisotropic photoelectron flux has been derived, which has been further utilized to characterize the charging of levitating fine particles in the lunar sheath along with other constituent photoemission and solar wind fluxes. This estimate of particle charge has been further manifested with lunar sheath characteristics to evaluate the altitude profile of the particle size exhibiting levitation. The inclusion of solar wind flux into analysis is noticed to reduce the sheath span and altitude of the particle levitation; the dependence of the sheath structure and particle levitation on the solar wind plasma parameters has been discussed and graphically presented.

Detection of fast nanoparticles in the solar wind

International Nuclear Information System (INIS)

Meyer-Vernet, N.; Maksimovic, M.; Lecacheux, A.; Le Chat, G.; Czechowski, A.; Mann, I.; Goetz, K.; Kaiser, M. L.; Cyr, O. C. St.; Bale, S. D.

2010-01-01

Dust grains in the nanometer range bridge the gap between atoms and larger grains made of bulk material. Their small size embodies them with special properties. Due to their high relative surface area, they have a high charge-to-mass ratio, so that the Lorentz force in the solar wind magnetic field exceeds the gravitational force and other forces by a large amount, and they are accelerated to a speed of the order of magnitude of the solar wind speed. When such fast nanoparticles impact a spacecraft, they produce craters whose matter vaporises and ionises, yielding transient voltages as high as do much larger grains of smaller speed. These properties are at the origin of their recent detection at 1 AU in the solar wind. We discuss the detection of fast nanoparticles by wave instruments of different configurations, with applications to the recent detections on STEREO/WAVES and CASSINI/RPWS. Finally we discuss the opportunities for nanoparticle detection by wave instruments on future missions and/or projects in the inner heliosphere such as Bepi-Colombo and Solar Orbiter.

Global Solar Magnetic Field Organization in the Outer Corona: Influence on the Solar Wind Speed and Mass Flux Over the Cycle

Science.gov (United States)

Réville, Victor; Brun, Allan Sacha

2017-11-01

The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11-year solar cycle. For instance, the wind terminal velocity is thought to be anti-correlated with the expansion factor, a measure of how the magnetic field varies with height in the solar corona, usually computed at a fixed height (≈ 2.5 {R}⊙ , the source surface radius that approximates the distance at which all magnetic field lines become open). However, the magnetic field expansion affects the solar wind in a more detailed way, its influence on the solar wind properties remaining significant well beyond the source surface. We demonstrate this using 3D global magnetohydrodynamic (MHD) simulations of the solar corona, constrained by surface magnetograms over half a solar cycle (1989-2001). A self-consistent expansion beyond the solar wind critical point (even up to 10 {R}⊙ ) makes our model comply with observed characteristics of the solar wind, namely, that the radial magnetic field intensity becomes latitude independent at some distance from the Sun, and that the mass flux is mostly independent of the terminal wind speed. We also show that near activity minimum, the expansion in the higher corona has more influence on the wind speed than the expansion below 2.5 {R}⊙ .

Nonlinear Evolution of Observed Fast Streams in the Solar Wind - Micro-instabilities and Energy Exchange between Protons and Alpha Particles

Science.gov (United States)

Maneva, Y. G.; Poedts, S.

2017-12-01

Non-thermal kinetic components such as deformed velocity distributions, temperature anisotropies and relative drifts between the multiple ion populations are frequently observed features in the collisionless fast solar wind streams near the Earth whose origin is still to be better understood. Some of the traditional models consider the formation of the temperature anisotropies through the effect of the solar wind expansion, while others assume in situ heating and particle acceleration by local fluctuations, such as plasma waves, or by spacial structures, such as advected or locally generated current sheets. In this study we consider the evolution of initial ion temperature anisotropies and relative drifts in the presence of plasma oscillations, such as ion-cyclotron and kinetic Alfven waves. We perform 2.5D hybrid simulations to study the evolution of observed fast solar wind plasma parcels, including the development of the plasma micro-instabilities, the field-particle correlations and the energy transfer between the multiple ion species. We consider two distinct cases of highly anisotropic and quickly drifting protons which excite ion-cyclotron waves and of moderately anisotropic slower protons, which co-exist with kinetic Alfven waves. The alpha particles for both cases are slightly anisotropic in the beginning and remain anisotropic throughout the simulation time. Both the imposed magnetic fluctuations and the initial differential streaming decrease in time for both cases, while the minor ions are getting heated. Finally we study the effects of the solar wind expansion and discuss its implications for the nonlinear evolution of the system.

Solar Spots - Activities to Introduce Solar Energy into the K-8 Curricula.

Science.gov (United States)

Longe, Karen M.; McClelland, Michael J.

Following an introduction to solar technology which reviews solar heating and cooling, passive solar systems (direct gain systems, thermal storage walls, sun spaces, roof ponds, and convection loops), active solar systems, solar electricity (photovoltaic and solar thermal conversion systems), wind energy, and biomass, activities to introduce solar…

Predicting Ionization Rates from SEP and Solar Wind Proton Precipitation into the Martian Atmosphere

Science.gov (United States)

Jolitz, R.; Dong, C.; Lee, C. O.; Curry, S.; Lillis, R. J.; Brain, D.; Halekas, J. S.; Larson, D. E.; Bougher, S. W.; Jakosky, B. M.

2017-12-01

Precipitating energetic particles ionize planetary atmospheres and increase total electron content. At Mars, the solar wind and solar energetic particles (SEPs) can precipitate directly into the atmosphere because solar wind protons can charge exchange to become neutrals and pass through the magnetosheath, while SEPs are sufficiently energetic to cross the magnetosheath unchanged. In this study we will present predicted ionization rates and resulting electron densities produced by solar wind and SEP proton ionization during nominal solar activity and a CME shock front impact event on May 16 2016. We will use the Atmospheric Scattering of Protons and Energetic Neutrals (ASPEN) model to compare ionization by SEP and solar wind protons currently measured by the SWIA (Solar Wind Ion Analyzer) and SEP instruments aboard the MAVEN spacecraft. Results will help to quantify how the ionosphere responds to extreme solar events during solar minimum.

Self consistent MHD modeling of the solar wind from polar coronal holes

International Nuclear Information System (INIS)

Stewart, G. A.; Bravo, S.

1996-01-01

We have developed a 2D self consistent MHD model for solar wind flow from antisymmetric magnetic geometries. We present results in the case of a photospheric magnetic field which has a dipolar configuration, in order to investigate some of the general characteristics of the wind at solar minimum. As in previous studies, we find that the magnetic configuration is that of a closed field region (a coronal helmet belt) around the solar equator, extending up to about 1.6 R · , and two large open field regions centred over the poles (polar coronal holes), whose magnetic and plasma fluxes expand to fill both hemispheres in interplanetary space. In addition, we find that the different geometries of the magnetic field lines across each hole (from the almost radial central polar lines to the highly curved border equatorial lines) cause the solar wind to have greatly different properties depending on which region it flows from. We find that, even though our simplified model cannot produce realistic wind values, we can obtain a polar wind that is faster, less dense and hotter than equatorial wind, and found that, close to the Sun, there exists a sharp transition between the two wind types. As these characteristics coincide with observations we conclude that both fast and slow solar wind can originate from coronal holes, fast wind from the centre, slow wind from the border

The influence of solar active region evolution on solar wind streams, coronal hole boundaries and geomagnetic storms

International Nuclear Information System (INIS)

Gold, R.E.; Dodson-Prince, H.W.; Hedeman, E.R.; Roelof, E.C.

1982-01-01

We have studied solar and interplanetary data by identification of the heliographic longitudes of the coronal source regions of high speed solar wind streams and by mapping the velocities measured near earth back to the sun using the approximation of constant radial velocity. Interplay of active regions and solar wind were studied

Solar district heating and cooling: A review

DEFF Research Database (Denmark)

Perez-Mora, Nicolas; Bava, Federico; Andersen, Martin

2018-01-01

and decentralized solar district heating as well as block heating. For the different technologies, the paper describes commonly adopted control strategies, system configurations, types of installation, and integration. Real‐world examples are also given to provide a more detailed insight into how solar thermal...... technology can be integrated with district heating. Solar thermal technology combined with thermally driven chillers to provide cooling for cooling networks is also included in this paper. In order for a technology to spread successfully, not only technical but also economic issues need to be tackled. Hence......Both district heating and solar collector systems have been known and implemented for many years. However, the combination of the two, with solar collectors supplying heat to the district heating network, is relatively new, and no comprehensive review of scientific publications on this topic could...

Effect of solar UV/EUV heating on the intensity and spatial distribution of Jupiter's synchrotron radiation

Science.gov (United States)

Kita, H.; Misawa, H.; Tsuchiya, F.; Tao, C.; Morioka, A.

2013-10-01

We analyzed the Very Large Array archived data observed in 2000 to determine whether solar ultraviolet (UV)/extreme ultraviolet (EUV) heating of the Jovian thermosphere causes variations in the total flux density and dawn-dusk asymmetry (the characteristic differences between the peak emissions at dawn and dusk) of Jupiter's synchrotron radiation (JSR). The total flux density varied by 10% over 6 days of observations and accorded with theoretical expectations. The average dawn-dusk peak emission ratio indicated that the dawn side emissions were brighter than those on the dusk side and this was expected to have been caused by diurnal wind induced by the solar UV/EUV. The daily variations in the dawn-dusk ratio did not correspond to the solar UV/EUV, and this finding did not support the theoretical expectation that the dawn-dusk ratio and diurnal wind velocity varies in correspondence with the solar UV/EUV. We tried to determine whether the average dawn-dusk ratio could be explained by a reasonable diurnal wind velocity. We constructed an equatorial brightness distribution model of JSR using the revised Divine-Garrett particle distribution model and used it to derive a relation between the dawn-dusk ratio and diurnal wind velocity. The estimated diurnal wind velocity reasonably corresponded to a numerical simulation of the Jovian thermosphere. We also found that realistic changes in the diurnal wind velocity could not cause the daily variations in the dawn-dusk ratio. Hence, we propose that the solar UV/EUV related variations were below the detection limit and some other processes dominated the daily variations in the dawn-dusk ratio.

Long-term solar wind electron variations between 1971 and 1978

International Nuclear Information System (INIS)

Feldman, W.C.; Asbridge, J.R.; Bame, S.J.; Gosling, J.T.

1979-01-01

Imp solar wind electron data measured between 1971 and 1978 were studied with the aim of determining long-term variations near the earth. Two separate sets of parameter variations were observed: (1) in 1976--1977 the solar wind density, the electron temperature, and the interplanetary electrostatic potential were all enhanced, and (2) the halo density and associated electron parameters were all depressed during a 1 1/2-year period centered on the last 6 months of 1976. Although interpretation of these results in terms of corresponding coronal and interplanetary variations is not unique, it may be significant that measured solar wind parameters near the minimum of solar cycle 20 agree better with the Hartle-Sturrock model of the coronal expansion than they do during other epochs

A model for the origin of solar wind stream interfaces

International Nuclear Information System (INIS)

Hundhausen, A.J.; Burlaga, L.F.

1975-01-01

The basic variations in solar wind properties that have been observed at 'stream interfaces' near 1 AU are explained by a gas dynamic model in which a radially propagating stream, produced by a temperature variation in the solar envelope, steepens nonlinearly while moving through interplanetary space. The region thus identified with the stream interface separates the ambient solar wind from the fresh hot material originally in the stream. However, the interface regions given by the present model are thicker than most stream interfaces observed in the solar wind, a fact suggesting that some additional physical process may be important in determining that thickness. Variations in the density, speed, or Alfven pressure alone appear not to produce streams with such an interface

Solar Heating Systems with Evacuated Tubular Solar Collector

DEFF Research Database (Denmark)

Qin, Lin; Furbo, Simon

1998-01-01

Recently different designed evacuated tubular solar collectors were introduced on the market by different Chinese companies. In the present study, investigations on the performance of four different Chinese evacuated tubular collectors and of solar heating systems using these collectors were...... carried out, employing both laboratory test and theoretical calculations. The collectors were tested in a small solar domestic hot water (SDHW) system in a laboratory test facility under realistic conditions. The yearly thermal performance of solar heating systems with these evacuated tubular collectors......, as well as with normal flat-plate collectors was calculated under Danish weather conditions. It is found that, for small SDHW systems with a combi tank design, an increase of 25% -55% net utilized solar energy can be achieved by using these evacuated tubular collectors instead of normal flat...

The Parametric Decay Instability of Alfvén Waves in Turbulent Plasmas and the Applications in the Solar Wind

Energy Technology Data Exchange (ETDEWEB)

Shi, Mijie; Xiao, Chijie; Wang, Xiaogang [State Key Laboratory of Nuclear Physics and Technology, Fusion Simulation Center, School of Physics, Peking University, Beijing 100871 (China); Li, Hui, E-mail: cjxiao@pku.edu.cn [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2017-06-10

We perform three-dimensional ideal magnetohydrodynamic (MHD) simulations to study the parametric decay instability (PDI) of Alfvén waves in turbulent plasmas and explore its possible applications in the solar wind. We find that, over a broad range of parameters in background turbulence amplitudes, the PDI of an Alfvén wave with various amplitudes can still occur, though its growth rate in turbulent plasmas tends to be lower than both the theoretical linear theory prediction and that in the non-turbulent situations. Spatial–temporal FFT analyses of density fluctuations produced by the PDI match well with the dispersion relation of the slow MHD waves. This result may provide an explanation of the generation mechanism of slow waves in the solar wind observed at 1 au. It further highlights the need to explore the effects of density variations in modifying the turbulence properties as well as in heating the solar wind plasmas.

Implications of the Deep Minimum for Slow Solar Wind Origin

Science.gov (United States)

Antiochos, S. K.; Mikic, Z.; Lionello, R.; Titov, V. S.; Linker, J. A.

2009-12-01

The origin of the slow solar wind has long been one of the most important problems in solar/heliospheric physics. Two observational constraints make this problem especially challenging. First, the slow wind has the composition of the closed-field corona, unlike the fast wind that originates on open field lines. Second, the slow wind has substantial angular extent, of order 30 degrees, which is much larger than the widths observed for streamer stalks or the widths expected theoretically for a dynamic heliospheric current sheet. We propose that the slow wind originates from an intricate network of narrow (possibly singular) open-field corridors that emanate from the polar coronal hole regions. Using topological arguments, we show that these corridors must be ubiquitous in the solar corona. The total solar eclipse in August 2008, near the lowest point of the Deep Minimum, affords an ideal opportunity to test this theory by using the ultra-high resolution Predictive Science's (PSI) eclipse model for the corona and wind. Analysis of the PSI eclipse model demonstrates that the extent and scales of the open-field corridors can account for both the angular width of the slow wind and its closed-field composition. We discuss the implications of our slow wind theory for the structure of the corona and heliosphere at the Deep Minimum and describe further observational and theoretical tests. This work has been supported by the NASA HTP, SR&T, and LWS programs.

Evolution of the solar wind acceleration region during 1990-1994

International Nuclear Information System (INIS)

Tokumaru, Munetoshi; Kondo, Tetsuro; Takaba, Hiroshi; Mori, Hirotaka; Tanaka, Takashi

1996-01-01

The single-station measurements of interplanetary scintillation (IPS) at 2GHz and 8GHz using the Kashima radio telescope are used to study the distribution of the solar wind velocity and density fluctuations near the sun. Wind velocities derived from our IPS data with the IPS co-spectrum method show a radial increase in the distance range between 10 and 30 Rs (solar radii). From the scintillation index analysis, it is found that the radial fall of density fluctuations in the solar wind is described by the power-law function. A series of Kashima IPS observations reveals that a pronounced change in velocity and turbulence level occurs at the polar region of the sun during 1990-1994. That is, the high-speed wind and the reduced-turbulence region develop there as the solar activity declines. This fact is consistent with the long-term evolution of the coronal magnetic structure inferred from He1083nm observations

Saturn radio emission and the solar wind - Voyager-2 studies

International Nuclear Information System (INIS)

Desch, M.D.; Rucker, H.O.; Observatorium Lustbuhel, Graz, Austria)

1985-01-01

Voyager 2 data from the Plasma Science experiment, the Magnetometer experiment and the Planetary Radio Astronomy experiment were used to analyze the relationship between parameters of the solar wind/interplanetary medium and the nonthermal Saturn radiation. Solar wind and interplanetary magnetic field properties were combined to form quantities known to be important in controlling terrestrial magnetospheric processes. The Voyager 2 data set used in this investigation consists of 237 days of Saturn preencounter measurements. However, due to the immersion of Saturn and the Voyager 2 spacecraft into the extended Jupiter magnetic tail, substantial periods of the time series were lacking solar wind data. To cope with this problem a superposed epoch method (CHREE analysis) was used. The results indicate the superiority of the quantities containing the solar wind density in stimulating the radio emission of Saturn - a result found earlier using Voyager 1 data - and the minor importance of quantities incorporating the interplanetary magnetic field. 10 references

Solar wind reconstruction from magnetosheath data using an adjoint approach

International Nuclear Information System (INIS)

Nabert, C.; Othmer, C.

2015-01-01

We present a new method to reconstruct solar wind conditions from spacecraft data taken during magnetosheath passages, which can be used to support, e.g., magnetospheric models. The unknown parameters of the solar wind are used as boundary conditions of an MHD (magnetohydrodynamics) magnetosheath model. The boundary conditions are varied until the spacecraft data matches the model predictions. The matching process is performed using a gradient-based minimization of the misfit between data and model. To achieve this time-consuming procedure, we introduce the adjoint of the magnetosheath model, which allows efficient calculation of the gradients. An automatic differentiation tool is used to generate the adjoint source code of the model. The reconstruction method is applied to THEMIS (Time History of Events and Macroscale Interactions during Substorms) data to calculate the solar wind conditions during spacecraft magnetosheath transitions. The results are compared to actual solar wind data. This allows validation of our reconstruction method and indicates the limitations of the MHD magnetosheath model used.

Solar wind reconstruction from magnetosheath data using an adjoint approach

Energy Technology Data Exchange (ETDEWEB)

Nabert, C.; Othmer, C. [Technische Univ. Braunschweig (Germany). Inst. fuer Geophysik und extraterrestrische Physik; Glassmeier, K.H. [Technische Univ. Braunschweig (Germany). Inst. fuer Geophysik und extraterrestrische Physik; Max Planck Institute for Solar System Research, Goettingen (Germany)

2015-07-01

We present a new method to reconstruct solar wind conditions from spacecraft data taken during magnetosheath passages, which can be used to support, e.g., magnetospheric models. The unknown parameters of the solar wind are used as boundary conditions of an MHD (magnetohydrodynamics) magnetosheath model. The boundary conditions are varied until the spacecraft data matches the model predictions. The matching process is performed using a gradient-based minimization of the misfit between data and model. To achieve this time-consuming procedure, we introduce the adjoint of the magnetosheath model, which allows efficient calculation of the gradients. An automatic differentiation tool is used to generate the adjoint source code of the model. The reconstruction method is applied to THEMIS (Time History of Events and Macroscale Interactions during Substorms) data to calculate the solar wind conditions during spacecraft magnetosheath transitions. The results are compared to actual solar wind data. This allows validation of our reconstruction method and indicates the limitations of the MHD magnetosheath model used.

ANALYSING SOLAR-WIND HYBRID POWER GENERATING SYSTEM

Directory of Open Access Journals (Sweden)

Mustafa ENGİN

2005-02-01

Full Text Available In this paper, a solar-wind hybrid power generating, system that will be used for security lighting was designed. Hybrid system was installed and solar cells, wind turbine, battery bank, charge regulators and inverter performance values were measured through the whole year. Using measured values of overall system efficiency, reliability, demanded energy cost per kWh were calculated, and percentage of generated energy according to resources were defined. We also include in the paper a discussion of new strategies to improve hybrid power generating system performance and demanded energy cost per kWh.

Costs of solar and wind power variability for reducing CO2 emissions.

Science.gov (United States)

Lueken, Colleen; Cohen, Gilbert E; Apt, Jay

2012-09-04

We compare the power output from a year of electricity generation data from one solar thermal plant, two solar photovoltaic (PV) arrays, and twenty Electric Reliability Council of Texas (ERCOT) wind farms. The analysis shows that solar PV electricity generation is approximately one hundred times more variable at frequencies on the order of 10(-3) Hz than solar thermal electricity generation, and the variability of wind generation lies between that of solar PV and solar thermal. We calculate the cost of variability of the different solar power sources and wind by using the costs of ancillary services and the energy required to compensate for its variability and intermittency, and the cost of variability per unit of displaced CO(2) emissions. We show the costs of variability are highly dependent on both technology type and capacity factor. California emissions data were used to calculate the cost of variability per unit of displaced CO(2) emissions. Variability cost is greatest for solar PV generation at $8-11 per MWh. The cost of variability for solar thermal generation is $5 per MWh, while that of wind generation in ERCOT was found to be on average $4 per MWh. Variability adds ~$15/tonne CO(2) to the cost of abatement for solar thermal power, $25 for wind, and $33-$40 for PV.

EFFICIENCY AND LIFETIME OF SOLAR COLLECTORS FOR SOLAR HEATING PLANTS

DEFF Research Database (Denmark)

The 12.5 m² flat plate solar collector HT, today marketed by Arcon Solvarme A/S, has been used in solar heating plants in Scandinavia since 1983. The collector is designed to operate in a temperature interval between 40°C and 90°C. The efficiency of the collector has been strongly improved since...... it was introduced on the market. The paper will present the increase of the efficiency of the collector due to technical improvements since 1983. Further, measurements from the spring of 2009 of the efficiency of two HT collectors, which have been in operation in the solar heating plant Ottrupgaard, Skørping......, Denmark since 1994 with a constant high flow rate and in the solar heating plant Marstal, Denmark since 1996 with a variable flow rate, will be presented. The efficiencies will be compared to the efficiencies of the collectors when they were first installed in the solar heating plants. The measurements...

EFFICIENCY AND LIFETIME OF SOLAR COLLECTORS FOR SOLAR HEATING PLANTS

DEFF Research Database (Denmark)

Fan, Jianhua; Chen, Ziqian; Furbo, Simon

2009-01-01

The 12.5 m² flat plate solar collector HT, today marketed by Arcon Solvarme A/S, has been used in solar heating plants in Scandinavia since 1983. The collector is designed to operate in a temperature interval between 40°C and 90°C. The efficiency of the collector has been strongly improved since...... it was introduced on the market. The paper will present the increase of the efficiency of the collector due to technical improvements since 1983. Further, measurements from the spring of 2009 of the efficiency of two HT collectors, which have been in operation in the solar heating plant Ottrupgaard, Skørping......, Denmark since 1994 with a constant high flow rate and in the solar heating plant Marstal, Denmark since 1996 with a variable flow rate, will be presented. The efficiencies will be compared to the efficiencies of the collectors when they were first installed in the solar heating plants. The measurements...

Wind power integration using individual heat pumps – Analysis of different heat storage options

DEFF Research Database (Denmark)

Hedegaard, Karsten; Mathiesen, Brian Vad; Lund, Henrik

2012-01-01

Significant installations of individual heat pumps are expected in future energy systems due to their economic competitiveness. This case study of the Danish energy system in 2020 with 50% wind power shows that individual heat pumps and heat storages can contribute to the integration of wind power....... Heat accumulation tanks and passive heat storage in the construction are investigated as two alternative storage options in terms of their ability to increase wind power utilisation and to provide cost-effective fuel savings. Results show that passive heat storage can enable equivalent to larger...... reductions in excess electricity production and fuel consumption than heat accumulation tanks. Moreover, passive heat storage is found to be significantly more cost-effective than heat accumulation tanks. In terms of reducing fuel consumption of the energy system, the installation of heat pumps is the most...

Predicting Atmospheric Ionization and Excitation by Precipitating SEP and Solar Wind Protons Measured By MAVEN

Science.gov (United States)

Jolitz, Rebecca; Dong, Chuanfei; Lee, Christina; Lillis, Rob; Brain, David; Curry, Shannon; Halekas, Jasper; Bougher, Stephen W.; Jakosky, Bruce

2017-10-01

Precipitating energetic particles ionize and excite planetary atmospheres, increasing electron content and producing aurora. At Mars, the solar wind and solar energetic particles (SEPs) can precipitate directly into the atmosphere because solar wind protons can charge exchange to become neutral and pass the magnetosheath, and SEPs are sufficiently energetic to cross the magnetosheath unchanged. We will compare ionization and Lyman alpha emission rates for solar wind and SEP protons during nominal solar activity and a CME shock front impact event on May 16 2016. We will use the Atmospheric Scattering of Protons and Energetic Neutrals (ASPEN) model to compare excitation and ionization rates by SEPs and solar wind protons currently measured by the SWIA (Solar Wind Ion Analyzer) and SEP instruments aboard the MAVEN spacecraft. Results will help quantify how SEP and solar wind protons influence atmospheric energy deposition during solar minimum.

Effects of the Solar Wind Pressure on Mercury's Exosphere: Hybrid Simulations

Science.gov (United States)

Travnicek, P. M.; Schriver, D.; Orlando, T. M.; Hellinger, P.

2017-12-01

We study effects of the changed solar wind pressure on the precipitation of hydrogen on the Mercury's surface and on the formation of Mercury's magnetosphere. We carry out a set of global hybrid simulations of the Mercury's magnetosphere with the interplanetary magnetic field oriented in the equatorial plane. We change the solar wind pressure by changing the velocity of injected solar wind plasma (vsw = 2 vA,sw; vsw = 4 vA,sw; vsw = 6 vA,sw). For each of the cases we examine proton and electron precipitation on Mercury's surface and calculate yields of heavy ions released from Mercury's surface via various processes (namely: Photo-Stimulated Desorption, Solar Wind Sputtering, and Electron Stimulated Desorption). We study circulation of the released ions within the Mercury's magnetosphere for the three cases.

Coronal mass ejections and disturbances in solar wind plasma parameters in relation with geomagnetic storms

International Nuclear Information System (INIS)

Verma, P L; Singh, Puspraj; Singh, Preetam

2014-01-01

Coronal Mass Ejections (CMEs) are the drastic solar events in which huge amount of solar plasma materials are ejected into the heliosphere from the sun and are mainly responsible to generate large disturbances in solar wind plasma parameters and geomagnetic storms in geomagnetic field. We have studied geomagnetic storms, (Dst ≤-75 nT) observed during the period of 1997-2007 with Coronal Mass Ejections and disturbances in solar wind plasma parameters (solar wind temperature, velocity, density and interplanetary magnetic field) .We have inferred that most of the geomagnetic storms are associated with halo and partial halo Coronal Mass Ejections (CMEs).The association rate of halo and partial halo coronal mass ejections are found 72.37 % and 27.63 % respectively. Further we have concluded that geomagnetic storms are closely associated with the disturbances in solar wind plasma parameters. We have determined positive co-relation between magnitudes of geomagnetic storms and magnitude of jump in solar wind plasma temperature, jump in solar wind plasma density, jump in solar wind plasma velocity and jump in average interplanetary magnetic field with co-relation co-efficient 0 .35 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma temperature, 0.19 between magnitude of geomagnetic storms and magnitude of jump in solar wind density, 0.34 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma velocity, 0.66 between magnitude of geomagnetic storms and magnitude of jump in average interplanetary magnetic field respectively. We have concluded that geomagnetic storms are mainly caused by Coronal Mass Ejections and disturbances in solar wind plasma parameters that they generate.

A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples.

Science.gov (United States)

Marty, B; Chaussidon, M; Wiens, R C; Jurewicz, A J G; Burnett, D S

2011-06-24

The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a (15)N/(14)N ratio of 2.18 ± 0.02 × 10(-3) (that is, ≈40% poorer in (15)N relative to terrestrial atmosphere). The (15)N/(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10(-3), which is the lowest (15)N/(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the (15)N-depleted components observed in solar system reservoirs.

The study of the heat-engineering characteristics of a solar heat collector based on aluminum heat pipes

International Nuclear Information System (INIS)

Khairnasov, S.M.; Zaripov, V.K.; Passamakin, B.M. et al.

2013-01-01

This paper presents the results of studies into the heat-engineering characteristics of a flat heat solar collector based on aluminum heat pipes that is designed to be used in building facades. The principle of work and the structure of the solar collector are considered; the results of its comparison with a traditional flat solar collector are presented. The studies were performed at a heat carrier temperature range of +10 - +30 degree C and at a solar heat flow density of 400 - 1000 W/m 2 . The obtained experimental heat-engineering characteristics of the collector based on heat pipes show that they are at a level of traditional flow solar collectors; for example, its efficiency is 0.65 - 0.73. Meanwhile, the hydraulic resistance of the structure with heat pipes is by a factor of 2 - 2.4 smaller and ensures a high level of scalability, reliability, and maintainability, which is important when using it as an element of facade constructions of solar heat systems. (author)

Turbulence in the solar wind

CERN Document Server

Bruno, Roberto

2016-01-01

This book provides an overview of solar wind turbulence from both the theoretical and observational perspective. It argues that the interplanetary medium offers the best opportunity to directly study turbulent fluctuations in collisionless plasmas. In fact, during expansion, the solar wind evolves towards a state characterized by large-amplitude fluctuations in all observed parameters, which resembles, at least at large scales, the well-known hydrodynamic turbulence. This text starts with historical references to past observations and experiments on turbulent flows. It then introduces the Navier-Stokes equations for a magnetized plasma whose low-frequency turbulence evolution is described within the framework of the MHD approximation. It also considers the scaling of plasma and magnetic field fluctuations and the study of nonlinear energy cascades within the same framework. It reports observations of turbulence in the ecliptic and at high latitude, treating Alfvénic and compressive fluctuations separately in...

NEMO 2 - Be aware: Wind and solar are coming

Energy Technology Data Exchange (ETDEWEB)

Lund, P. [Helsinki Univ. of Technology, Otaniemi (Finland)

1996-12-31

Finnish research and development is well placed with respect to new renewable energy technologies in that there exists considerable expertise in specialized areas. For example, over 20 % of all power transmission equipment and generators used in wind energy systems world-wide are manufactured in Finland, while advanced instruments for monitoring wind speed are also highly regarded internationally. Moreover, unique wind technology for complex windy and freezing conditions have been developed. Finland has a 10 % share in the European photovoltaic market, and has competitive advantages in photovoltaic systems and applications, thin film solar cells, and automated electronic controlling systems. A unique solar energy storage system based on hydrogen technology demonstrates skills on overcoming the summer-winter syndrome of large-scale solar energy utilization. The annual turnover of the Finnish industries on solar and wind energy has increased from 5 million ECU in 1988 to almost 50 million ECU in 1996. The national R and D and D from 1988 onwards has played an important role in this context. Most of the research and development into new and renewable energy technologies in Finland has been carried out through the Advanced New Energy Systems and Technologies Research Programme (NEMO2) of Tekes

Solar wind dynamic pressure variations and transient magnetospheric signatures

International Nuclear Information System (INIS)

Sibeck, D.G.; Baumjohann, W.

1989-01-01

Contrary to the prevailing popular view, we find some transient ground events with bipolar north-south signatures are related to variations in solar wind dynamic pressure and not necessarily to magnetic merging. We present simultaneous solar wind plasma observations for two previously reported transient ground events observed at dayside auroral latitudes. During the first event, originally reported by Lanzerotti et al. [1987], conjugate ground magnetometers recorded north-south magetic field deflections in the east-west and vertical directions. The second event was reported by Todd et al. [1986], we noted ground rader observations indicating strong northward then southward ionospheric flows. The events were associated with the postulated signatures of patchy, sporadic, merging of magnetosheath and magnetospheric magnetic field lines at the dayside magnetospause, known as flux transfer events. Conversely, we demonstrate that the event reported by Lanzerotti et al. was accompanied by a sharp increase in solar wind dynamic pressure, a magnetospheric compression, and a consequent ringing of the magnetospheric magnetic field. The event reported by Todd et al. was associated with a brief but sharp increase in the solar wind dynamic pressure. copyright American Geophysical Union 1989

The 3-D solar radioastronomy and the structure of the corona and the solar wind. [solar probes of solar activity

Science.gov (United States)

Steinberg, J. L.; Caroubalos, C.

1976-01-01

The mechanism causing solar radio bursts (1 and 111) is examined. It is proposed that a nonthermal energy source is responsible for the bursts; nonthermal energy is converted into electromagnetic energy. The advantages are examined for an out-of-the-ecliptic solar probe mission, which is proposed as a means of stereoscopically viewing solar radio bursts, solar magnetic fields, coronal structure, and the solar wind.

ULF Wave Activity in the Magnetosphere: Resolving Solar Wind Interdependencies to Identify Driving Mechanisms

Science.gov (United States)

Bentley, S. N.; Watt, C. E. J.; Owens, M. J.; Rae, I. J.

2018-04-01

Ultralow frequency (ULF) waves in the magnetosphere are involved in the energization and transport of radiation belt particles and are strongly driven by the external solar wind. However, the interdependency of solar wind parameters and the variety of solar wind-magnetosphere coupling processes make it difficult to distinguish the effect of individual processes and to predict magnetospheric wave power using solar wind properties. We examine 15 years of dayside ground-based measurements at a single representative frequency (2.5 mHz) and a single magnetic latitude (corresponding to L ˜ 6.6RE). We determine the relative contribution to ULF wave power from instantaneous nonderived solar wind parameters, accounting for their interdependencies. The most influential parameters for ground-based ULF wave power are solar wind speed vsw, southward interplanetary magnetic field component Bzstill account for significant amounts of power. We suggest that these three parameters correspond to driving by the Kelvin-Helmholtz instability, formation, and/or propagation of flux transfer events and density perturbations from solar wind structures sweeping past the Earth. We anticipate that this new parameter reduction will aid comparisons of ULF generation mechanisms between magnetospheric sectors and will enable more sophisticated empirical models predicting magnetospheric ULF power using external solar wind driving parameters.

Observations of micro-turbulence in the solar wind near the sun with interplanetary scintillation

Science.gov (United States)

Yamauchi, Y.; Misawa, H.; Kojima, M.; Mori, H.; Tanaka, T.; Takaba, H.; Kondo, T.; Tokumaru, M.; Manoharan, P. K.

1995-01-01

Velocity and density turbulence of solar wind were inferred from interplanetary scintillation (IPS) observations at 2.3 GHz and 8.5 GHz using a single-antenna. The observations were made during September and October in 1992 - 1994. They covered the distance range between 5 and 76 solar radii (Rs). We applied the spectrum fitting method to obtain a velocity, an axial ratio, an inner scale and a power-law spectrum index. We examined the difference of the turbulence properties near the Sun between low-speed solar wind and high-speed solar wind. Both of solar winds showed acceleration at the distance range of 10 - 30 Rs. The radial dependence of anisotropy and spectrum index did not have significant difference between low-speed and high-speed solar winds. Near the sun, the radial dependence of the inner scale showed the separation from the linear relation as reported by previous works. We found that the inner scale of high-speed solar wind is larger than that of low-speed wind.

GPP Webinar: Market Outlook and Innovations in Wind and Solar Power

Science.gov (United States)

Green Power Partnership webinar reviewing the state of the renewable energy industry as a whole, with a focus on wind and solar power and exploring recent marketplace innovations in wind and solar power and renewable energy purchases.

Low-cost solution to the grid reliability problem with 100% penetration of intermittent wind, water, and solar for all purposes.

Science.gov (United States)

Jacobson, Mark Z; Delucchi, Mark A; Cameron, Mary A; Frew, Bethany A

2015-12-08

This study addresses the greatest concern facing the large-scale integration of wind, water, and solar (WWS) into a power grid: the high cost of avoiding load loss caused by WWS variability and uncertainty. It uses a new grid integration model and finds low-cost, no-load-loss, nonunique solutions to this problem on electrification of all US energy sectors (electricity, transportation, heating/cooling, and industry) while accounting for wind and solar time series data from a 3D global weather model that simulates extreme events and competition among wind turbines for available kinetic energy. Solutions are obtained by prioritizing storage for heat (in soil and water); cold (in ice and water); and electricity (in phase-change materials, pumped hydro, hydropower, and hydrogen), and using demand response. No natural gas, biofuels, nuclear power, or stationary batteries are needed. The resulting 2050-2055 US electricity social cost for a full system is much less than for fossil fuels. These results hold for many conditions, suggesting that low-cost, reliable 100% WWS systems should work many places worldwide.

Solar heat-pipe wick modeling

Energy Technology Data Exchange (ETDEWEB)

Andraka, C.E.

1999-07-01

Stirling-cycle engines have been identified as a promising technology for the conversion of concentrated solar energy into usable electrical power. In previous experimental work, the author has demonstrated that a heat pipe receiver can significantly improve system performance over a directly-illuminated heater head. The design and operating conditions of a heat pipe receiver differ significantly from typical laboratory heat pipes. New wick structures have been developed to exploit the characteristics of the solar generation system. Typically, these wick structures allow vapor generation within the wick. Conventional heat pipe models do not handle this enhancement, yet it can more than double the performance of the wick. In this study, the author developed a steady-state model of a boiling-enhanced wick for a solar heat pipe receiver. The model is used for design-point calculations and is written in FORTRAN90. Some limited comparisons have been made with actual test data.

Solar-wind system powers mountain clean-up

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

By using a hybrid solar-wind system, the Japanese have tackled the problem of human excrement left by tourists in mountain lodges and in natural parks by installing flush toilets and wastewater treatment plants. The solar array (4.9 kW{sub p}) consists of 76 panels of single-crystal photovoltaic cells each with an output of 64 Wp. The wind turbines (total capacity 2.1 kW) operate whatever the wind strength or direction. Storage batteries prevent any dip in power which would result from low ambient temperatures. The system can still function at temperatures as low as minus 25{sup o}C. Between November and April when the lodge is closed, the waste is decomposed biologically. A block diagram shows the elements of the system, and details of cost are given. The system won the 1999 New Energy Award.

Enhancing information for solar and wind energy technology deployment in Brazil

Energy Technology Data Exchange (ETDEWEB)

Ramos Martins, Fernando, E-mail: fernando.martins@inpe.br [Centro de Ciencia do Sistema Terrestre-Instituto Nacisonal de Pesquisas Espaciais (Earth System Center-National Institute for Space Research), P.O. Box 515, 12245-970, Sao Jose dos Campos (Brazil); Pereira, Enio Bueno, E-mail: enio.pereira@inpe.br [Centro de Ciencia do Sistema Terrestre-Instituto Nacisonal de Pesquisas Espaciais (Earth System Center-National Institute for Space Research), P.O. Box 515, 12245-970, Sao Jose dos Campos (Brazil)

2011-07-15

Brazil's primary energy matrix is based on more than 47% of renewables, and more than 85% of its electricity is generated by hydro power sources. Despite this large fraction of renewable energy resources, less than 0.3% of the national energy supply comes from solar or wind sources. This paper presents a diagnostic review on the penetration of the solar and wind energy technologies in Brazil. It also includes a survey of the latest government policies and incentives for renewable energies deployment by entrepreneurs, industry and commercial and residential consumers. In addition, the paper analyses how to best meet the requirements for policy support and information technology to boost the deployment of solar technology and wind energy in Brazil. This study was mostly based on results of a widely distributed survey covering key issues, and also by personal interviews carried out with key stakeholders in order to better understand the issues highlighted in the survey responses. The study pointed out some of the main obstacles to effectively promote and improve government policies and actions for investment in solar and wind energy market in Brazil. - Highlights: > Current status on the solar and wind energy deployment in Brazil is presented. > Policy framework required to support solar and wind energy was discussed. > Study was based on responses for consultations with key stakeholders. > Worthiness Index was established to rank the stakeholders outlooks. > Energy price, human resources and tax reductions were indicated as priority.

Enhancing information for solar and wind energy technology deployment in Brazil