Download or read book Acceleration of Electrons and Ions by Strong Lower Hybrid Turbulence in Solar Flares written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-22 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the outstanding problems in solar flare theory is how to explain the 10-20 keV and greater hard x-ray emissions by a thick target bremsstrahlung model. The model requires the acceleration mechanism to accelerate approximately 10(exp 35) electrons sec(exp -l) with comparable energies, without producing a large return current which persists for long time scales after the beam ceases to exist due to Lenz's law, thereby, producing a self-magnetic field of order a few mega-Gauss. In this paper, we investigate particle acceleration resulting from the relaxation of unstable ion ring distributions, producing strong wave activity at the lower hybrid frequency. It is shown that strong lower hybrid wave turbulence collapses in configuration space producing density cavities containing intense electrostatic lower hybrid wave activity. The collapse of these intense nonlinear wave packets saturate by particle acceleration producing energetic electron and ion tails. There are several mechanisms whereby unstable ion distributions could be formed in the solar atmosphere, including reflection at perpendicular shocks, tearing modes, and loss cone depletion. Numerical simulations of ion ring relaxation processes, obtained using a 2 1/2-D fully electromagnetic, relativistic particle in cell code are discussed. We apply the results to the problem of explaining energetic particle production in solar flares. The results show the simultaneous acceleration of both electrons and ions to very high energies: electrons are accelerated to energies in the range 10-500 keV, while ions are accelerated to energies of the order of MeVs, giving rise to x-ray emission and gamma-ray emission respectively. Our simulations also show wave generation at the electron cyclotron frequency. We suggest that these waves are the solar millisecond radio spikes. The strong turbulence collapse process leads to a highly filamented plasma producing many localized regions for particle acceleration and resulting in ...
Download or read book Acceleration of Electrons and Ions by Strong Lower hybrid Turbulence in Solar Flares written by and published by . This book was released on 1994 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lower Hybrid Resonance Acceleration of Electrons and Ions in Solar Flares and the Associated Microwave Emission written by and published by . This book was released on 1992 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 1028 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Prompt Simultaneous Acceleration of Protons and Electrons to Relativistic Energies by Shock Waves in Solar Flares written by Yukiharu Ohsawa and published by . This book was released on 1987 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stochastic Acceleration of Electrons by Turbulence in Solar Flares written by Qingrong Chen and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar flares are among the most powerful explosions and most efficient particle accelerators in the solar system. The model of stochastic acceleration by plasma turbulence has been very instrumental in explaining the observed high-energy radiations and particles from solar flares. In this thesis, we aim to better constrain the electron acceleration and scattering processes by turbulence from hard X-ray imaging spectroscopic observations of solar flares. By utilizing the leaky box Fokker-Planck equation and the thick target equation describing particle acceleration and transport, we derive analytical formulas for the stochastic acceleration model quantities directly in terms of the accelerated and escaping particle spectra. Based on the hard X-ray radiating electron flux spectral images via regularized inversion, we determine the timescales for electron escape, pitch angle scattering, energy diffusion, and direct acceleration in two intense solar flares with a high-energy loop-top coronal source observed by the RHESSI mission. The existence of distinct coronal hard X-ray sources up to 100-150 keV in the impulsive phase indicates efficient confinement of high-energy electrons in the corona. The results that the electron escape time increases with energy and the acceleration time and scattering time exhibit very different energy dependences contradict existing predictions for stochastic acceleration due to wave-particle resonant interactions. The discrepancy between the observations and the acceleration model could be alleviated if the turbulence spectrum is much steeper than commonly assumed. A more plausible explanation for such events is that the escape of electrons from the loop-top acceleration region is not diffusive in nature due to scattering, but is affected by magnetic mirroring.
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 Particle Acceleration and Kinematics in Solar Flares written by Markus Aschwanden and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade we entered a new exploration phase of solar flare physics, equipped with powerful spacecraft such as Yohkoh, SoHO, and TRACE that pro vide us detail-rich and high-resolution images of solar flares in soft X-rays, hard X -rays, and extreme-ultraviolet wavelengths. Moreover, the large-area and high sensitivity detectors on the Compton GRO spacecraft recorded an unprecedented number of high-energy photons from solar flares that surpasses all detected high energy sources taken together from the rest of the universe, for which CGRO was mainly designed to explore. However, morphological descriptions of these beau tiful pictures and statistical catalogs of these huge archives of solar data would not convey us much understanding of the underlying physics, if we would not set out to quantify physical parameters from these data and would not subject these measurements to theoretical models. Historically, there has always been an unsatisfactory gap between traditional astronomy that dutifully describes the mor phology of observations, and the newer approach of astrophysics, which starts with physical concepts from first principles and analyzes astronomical data with the goal to confirm or disprove theoretical models. In this review we attempt to bridge this yawning gap and aim to present the recent developments in solar flare high-energy physics from a physical point of view, structuring the observations and analysis results according to physical processes, such as particle acceleration, propagation, energy loss, kinematics, and radiation signatures.
Download or read book Monthly Catalogue United States Public Documents written by and published by . This book was released on 1994-12 with total page 950 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monthly Catalog of United States Government Publications written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1994 with total page 1154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microphysics of Cosmic Plasmas written by André Balogh and published by Springer Science & Business Media. This book was released on 2014-01-15 with total page 631 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents a comprehensive review of physical processes in astrophysical plasmas. This title presents a review of the detailed aspects of the physical processes that underlie the observed properties, structures and dynamics of cosmic plasmas. An assessment of the status of understanding of microscale processes in all astrophysical collisionless plasmas is provided. The topics discussed include turbulence in astrophysical and solar system plasmas as a phenomenological description of their dynamic properties on all scales; observational, theoretical and modelling aspects of collisionless magnetic reconnection; the formation and dynamics of shock waves; and a review and assessment of microprocesses, such as the hierarchy of plasma instabilities, non-local and non-diffusive transport processes and ionisation and radiation processes. In addition, some of the lessons that have been learned from the extensive existing knowledge of laboratory plasmas as applied to astrophysical problems are also covered. This volume is aimed at graduate students and researchers active in the areas of cosmic plasmas and space science. Originally published in Space Science Reviews journal, Vol. 278/2-4, 2013.
Download or read book Particle Acceleration and Trapping in Solar Flares written by G. Trottet and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: These are the Proceedings of the Second CESRA Workshop on Particle Acceleration and Trapping in Solar Flares. The Workshop was held on June 23-26,1986, at the city hall of Aubigny-sur-Nere (France), near Bourges and near the Nan
Download or read book Proceedings of the International Workshop on Acceleration and Radiation Generation in Space and Laboratory Plasmas written by International Workshop on Acceleration and Radiation Generation in Space and Laboratory Plasmas and published by . This book was released on 1994 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multiscale Coupling of Sun Earth Processes written by A.T.Y. Lui and published by Elsevier. This book was released on 2005-07-06 with total page 527 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many approaches exist for scientific investigations and space research is no exception. The early approach during which each space plasma region within the Sun-Earth system was investigated separately with physics-based tools has now progressed to encompass investigations on coupling between these regions. Ample evidence now exists indicating the dynamic processes in these regions exhibit disturbances over a wide range of scales both in time and space. This new reckoning naturally leads to an emerging perspective of probing these natural phenomena with concepts and tools developed in modern statistical mechanics for physical processes governing the evolution of out-of-equilibrium and complex systems. These new developments have prompted a topical conference on Sun-Earth connection, held on February 9-13, 2004 at Kailua-Kona, Hawaii, USA, with the goal of promoting interactions among scientists practicing the traditional physics-based approach and those utilizing modern statistical techniques. This monograph is a product of this conference, a compilation of thirty-nine articles assembled into seven chapters: (1) multiscale features in complexity dynamics, (2) space storms, (3) magnetospheric substorms, (4) turbulence and magnetic reconnection, (5) modeling and coupling of space phenomena, (6) techniques for multiscale space plasma problems, and (7) present and future multiscale space missions. These articles show a diversity of space phenomena exhibiting scale free characteristics, intermittency, and non-Gaussian distributions of probability density function of fluctuations in the physical parameters of the Sun-Earth system. The scope covers the latest observations, theories, simulations, and techniques on the multiscale nature of Sun-Earth phenomena and underscores the usefulness in cross-disciplinary exchange needed to unravel the underlying physical processes, which may eventually lead to a possible unified description and prediction for space disturbances. * Extensive collection of state-of-the-art papers on multiscale coupling of Sun-Earth Processes * Present and future multiscale space missions * New techniques and models for performing multiscale analysis
Download or read book Plasma Astrophysics written by Arnold O. Benz and published by Springer Science & Business Media. This book was released on 2005-11-28 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook is intended as an introduction to the physics of solar and stellar coronae, emphasizing kinetic plasma processes. It is addressed to observational astronomers, graduate students, and advanced undergraduates without a ba- ground in plasma physics. Coronal physics is today a vast field with many different aims and goals. So- ing out the really important aspects of an observed phenomenon and using the physics best suited for the case is a formidable problem. There are already several excellent books, oriented toward the interests of astrophysicists, that deal with the magnetohydrodynamics of stellar atmospheres, radiation transport, and radiation theory. In kinetic processes, the different particle velocities play an important role. This is the case when particle collisions can be neglected, for example in very brief phenomena – such as one period of a high-frequency wave – or in effects produced by energetic particles with very long collision times. Some of the most persistent problems of solar physics, like coronal heating, shock waves, flare energy release, and particle acceleration, are likely to be at least partially related to such p- cesses. Study of the Sun is not regarded here as an end in itself, but as the source of information for more general stellar applications. Our understanding of stellar processes relies heavily, in turn, on our understanding of solar processes. Thus an introduction to what is happening in hot, dilute coronae necessarily starts with the plasma physics of our nearest star.
Download or read book Abstracts for the AGU Western Pacific Geophysics Meeting written by and published by . This book was released on 2008 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:
