Download or read book Energetic Electrons in Impulsive Solar Flares written by David Allen Batchelor and published by . This book was released on 1984 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energetics and Dynamics of Simple Impulsive Solar Flares written by and published by . This book was released on 1987 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energetics and Dynamics of Simple Impulsive Solar Flares written by R. Starr and published by . This book was released on 1987 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solar Energetic Particles written by Donald V. Reames and published by Springer. This book was released on 2017-03-10 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: This concise primer introduces the non-specialist reader to the physics of solar energetic particles (SEP) and systematically reviews the evidence for the two main mechanisms which lead to the so-called impulsive and gradual SEP events. More specifically, the timing of the onsets, the longitude distributions, the high-energy spectral shapes, the correlations with other solar phenomena (e.g. coronal mass ejections), as well as the all-important elemental and isotopic abundances of SEPs are investigated. Impulsive SEP events are related to magnetic reconnection in solar flares and jets. The concept of shock acceleration by scattering on self-amplified Alfvén waves is introduced, as is the evidence of reacceleration of impulsive-SEP material in the seed population accessed by the shocks in gradual events. The text then develops processes of transport of ions out to an observer. Finally, a new technique to determine the source plasma temperature in both impulsive and gradual events is demonstrated. Last but not least the role of SEP events as a radiation hazard in space is mentioned and a short discussion of the nature of the main particle telescope designs that have contributed to most of the SEP measurements is given.

Download or read book Dynamic Evolution of the Source Volumes of Gradual and Impulsive Solar Flare Emissions written by and published by . This book was released on 1987 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical Processes in Solar Flares written by B.V. Somov and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar flares are very complex electromagnetic phenomena of a cataclysmic nature. Particles are accelerated to very high velocities and a variety of physical processes happen inside and outside flares. These processes can be studied by a large number of techniques from Earth and from space. The aim is to discover the physics behind solar flares. This goal is complicated because information about the flare mechanism can be obtained only in an indirect way by studying the secondary effects. This book provides three stages in the solution of the solar flare problem. Chapter one describes the connection between observational data and theoretical concepts, where it is stressed that next to investigating flares, the related non-stationary large-scale phenomena must be studied as well. The second chapter deals with secondary physical processes, in particular the study of high-temperature plasma dynamics during impulsive heating. The last chapter presents a model built on the knowledge of the two previous chapters and it constructs a theory of non-neutral turbulent current sheets. The author believes that this model will help to solve the problem of solar flares. For solar physicists, plasma physicists, high-energy particle physicists.

Download or read book Radio and X Ray Evidence for Electron Acceleration in Solar Flares written by R. T. Stewart and published by . This book was released on 1982 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radio and X-ray observations, as well as gamma-ray and interplanetary electron observations, are briefly reviewed for evidence of electron acceleration during solar flares. The evidence suggests that in some large flares a second stage of particle acceleration takes place where ions and electrons are accelerated to very high energies. This second stage follows no more than several minutes after the first or impulsive stage, which occurs during the initial minute or so of the solar flare. During the impulsive phase electrons are accelerated to energies of approximately approx. 10-100 keV, probably by bulk energization, where stored magnetic energy is converted into thermal energy. Energy-loss arguments favor the electrons having a quasi-thermal (near-Maxwellian) electron velocity distribution. During large flares second-phase electrons are accelerated to much higher energies, approx. 10 MeV, and appear to have a power-law velocity distribution. The second-stage acceleration mechanism may be associated with a coronal shock wave, but so far there is no clear evidence that electrons with energies> or = 100 keV are directly associated with a shock wave. (Author).

Download or read book Energetic Phenomena on the Sun written by Mukul Ranjan Kundu and published by . This book was released on 1987 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Impulsive Hard X rays from Solar Flares written by John Leach and published by . This book was released on 1984 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solar Impulsive Energetic Electron Events written by Linghua Wang and published by . This book was released on 2009 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Sun is capable of accelerating ions from 0∼ tens of keV up to tens of GeV and electrons from 0∼ tens of eV up to hundreds of MeVs in transient events such as flares and fast coronal mass ejections (CMEs). The energized particles escaping into the interplanetary medium are referred to as Solar Energetic Particle (SEP) events. The great majority of SEP events are impulsive SEP events that are dominated by 0∼1-100 keV electrons and 0∼MeV/nucleon ion emissions, with enhanced 3He/4He ratios up to 104 times the coronal values (also called electron/3He-rich SEP events). This thesis is focused on solar impulsive energetic electron events, the electron part of impulsive SEP events, using electron observations from the 3-D Plasma and Energetic Particle instrument (3DP) on the WIND spacecraft near the Earth. First, I present the first comprehensive statistical study of solar energetic electron events over almost one solar cycle. I find that the occurrence rate of solar electron events shows a strong solar-cycle variation; after correction for the background effect, the estimated occurrence frequency exhibits a good power-law distribution, and the estimated occurrence rate near the Earth is 0∼1000/year at solar maximum and 0∼30/year at solar minimum for the instrumental sensitivity (0∼2.90×10-4 (cm3 s str eV)-1 for the 40 keV channel) of WIND/3DP, about one order of magnitude larger than the observed occurrence rate. Solar energetic electron events have a one-to-one association with type III radio bursts and a poor association with flares, but a close association with 3He-rich ion emissions. These 3He-rich electron events also have a poor association with flares but a close (0∼ 60%) association with west-limb CMEs. Then I present two case studies: one investigating the temporal relationship between solar impulsive electrons and type III radio emissions, and the second studying the temporal relationship between solar impulsive electrons and 3He-rich ions. For both studies, I chose nearly scatter-free electron events and developed a forward-fitting method that assumes an isosceles triangular injection profile (equal rise and fall times) at the Sun. I find that in electron/3He-rich SEP events, the low-energy (0∼0.4 to 6-9 keV) electron injection starts 0∼9 min before the coronal release of the type III radio burst; the high-energy (0∼13 to 0∼300 keV) electron injection starts 0∼8 min after the type III burst; and the injection of 0∼MeV/nucleon, 3He-rich ions begins 0∼1 hour later. I also find that the selected electron/3He-rich SEP events have a remarkable one-to-one association with fast west-limb CMEs, and most of the associated CMEs are narrow. Finally, I present a case study to investigate the propagation of different energy electrons in solar impulsive electron events. I find that in the interplanetary medium, low-energy (0∼ 10-30 keV) and high-energy (0∼ 10-30 keV) electrons propagate differently, with more scattering at high energies. Such scattering appears to be caused by resonance with waves/turbulence at scale greater than 0∼ the thermal proton gyroradius in the solar wind. Although a transition to more scattering occurs at energies where the electron injection delays are detected, I show that the scattering is not enough to produce these delays. Based on the results of this thesis, a coherent picture of electron/3He-rich SEP events can be built up. At the Sun, the low-energy (0∼0.4 to 6-9 keV) electrons may be accelerated in jets that are ejected upward from magnetic reconnection sites between closed and open field lines; these low-energy electrons generate the type III radio bursts. The jets may appear as CMEs high in the corona, and the high-energy (0∼13 to 0∼300 keV) electrons may then be accelerated at>0∼ 1 RS by CMEs, acting on the seed electrons provided by the low-energy injection. The 0∼MeV/nucleon, 3He-rich ions may be accelerated by selective resonance with electron-beam generated waves and/or by fast, narrow CMEs. In the interplanetary medium, both low and high energy electrons often propagate nearly scatter-free, but the high-energy electrons experience more scattering than the low-energy electrons, likely by waves/turbulence generated by solar wind ions. In the future, the upcoming missions to visit the inner heliosphere within 0∼0.2 AU (Solar Orbiter) or 0∼10 RS (Solar Probe Plus) will provide the near-Sun measurements to improve our understanding of SEP events.

Download or read book The Imulsive Phase of Solar Flares written by Joan Welter Vorpahl and published by . This book was released on 1971 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solar Flare Loops Observations and Interpretations written by Guangli Huang and published by Springer. This book was released on 2018-01-31 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides results of analysis of typical solar events, statistical analysis, the diagnostics of energetic electrons and magnetic field, as well as the global behavior of solar flaring loops such as their contraction and expansion. It pays particular attention to analyzing solar flare loops with microwave, hard X-ray, optical and EUV emissions, as well as the theories of their radiation, and electron acceleration/transport. The results concerning influence of the pitch-angle anisotropy of non-thermal electrons on their microwave and hard X-ray emissions, new spectral behaviors in X-ray and microwave bands, and results related to the contraction of flaring loops, are widely discussed in the literature of solar physics. The book is useful for graduate students and researchers in solar and space physics.

Download or read book Energy Release and Particle Acceleration in the Solar Atmosphere written by Brian R. Dennis and published by . This book was released on 2003 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Impulsive Solar X ray Bursts Bremsstrahlung Radiation from a Beam of Electrons in the Solar Chromosphere and the Total Energy of Solar Flares written by Stanford University. Institute for Plasma Research and published by . This book was released on 1973 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Advanced Composition Explorer Mission written by C.T. Russell and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 667 pages. Available in PDF, EPUB and Kindle. Book excerpt: NASA's Advanced Composition Explorer (ACE) was launched on August 25, 1997, carrying six high-resolution spectrometers that measure the abundances of the elements, isotopes, and ionic charge states of energetic nuclei in space. Data from these instruments is being used to measure and compare the composition of the solar corona, the nearby interstellar medium, and cosmic-ray sources in the Galaxy, and to study particle acceleration processes in a variety of environments. ACE also includes three instruments that monitor solar wind and energetic particle activity near the inner Lagrangian point, "1.5 million kilometers sunward of Earth, and provide continuous, real-time data to NOAA for use in forecasting space weather. Eleven of the articles in this volume review scientific progress and outline questions that ACE will address in solar, space-plasma, and cosmic-ray physics. Other articles describe the ACE spacecraft, the real-time solar-wind system, and the instruments used to measure energetic particle composition.

Download or read book The Role of the Big Flare Syndrome in Correlations of Solar Energetic Proton Fluxes and Associated Microwave Burst Parameters written by S. W. Kahler and published by . This book was released on 1981 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: In previous studies correlating E> 10 MeV proton fluxes and spectra with various associated microwave burst parameters, the resulting high correlations were assumed to reflect a common acceleration process for the protons and the microwave-emitting electrons. We suggest and test an alternative explanation for these correlations, which we term the Big Flare Syndrome (BFS), that states that, statistically, energetic flare phenomena are more intense in larger flares, regardless of the detailed physics. Peak 1-8 A X-ray fluxes, characteristic of the thermal flare, are correlated with peak proton fluxes to derive correlation coefficients characteristics of the BFS. Of all microwave parameters tested for the 1973-1979 period, only the time-integrated flux densities at 8800 and 15400 MHz may be significantly larger than expected form the BFS. We fail to confirm previous results associating peak proton spectra with peak microwave spectral characteristics, thus finding no evidence that peak microwave fluxes are indicative of proton acceleration. We extend this conclusion to peak hard X-ray correlations. The strongly nonlinear relationship deduced between flare energy and proton production also appears invalid.

Download or read book A Thermal nonthermal Approach to Solar Flares written by Stephen G. Benka and published by . This book was released on 1991 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: