74 research outputs found
Electron acceleration and ionization fronts induced by high frequency plasma turbulence
There are recent observations of artificial plasmas created during ionospheric modification experiments, in which intense radio waves are injected into the overhead ionosphere by ground-based transmitters. The plasma is formed just below the reflection point of the ordinary wave mode, where Langmuir and upper hybrid turbulence take place. When the plasma builds up, the radio wave is reflected at a lower altitude, and an ionization front is formed, rapidly descending to an altitude a few tens of kilometres below the initial critical layer. The ionization of the neutral gas is attributed to collisions with energetic electrons accelerated by the plasma wave turbulence. Numerical full-scale modeling of the Langmuir turbulence, electron acceleration and transport, and ionization processes are consistent with the observations. By a similarity principle, the experiment can be scaled down from the large-scale ionosphere to a metre-scale laboratory plasma, where microwaves are used instead of radio waves to induce the plasma turbulence. Such laboratory experiments under controlled conditions are now planned at Strathclyde, and may lead to new methods for electron acceleration and plasma generation in the laboratory
Rayleigh-Taylor and Richtmyer-Meshkov instabilities: A journey through scales
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordHydrodynamic instabilities such as Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities usually appear
in conjunction with the Kelvin-Helmholtz (KH) instability and are found in many natural phenomenon and engineering applications. They frequently result in turbulent mixing, which has a major impact on the overall flow development
and other effective material properties. This can either be a desired outcome, an unwelcome side effect, or just an unavoidable consequence, but must in all cases be characterized in any model. The RT instability occurs at an interface
between different fluids, when the light fluid is accelerated into the heavy. The RM instability may be considered a
special case of the RT instability, when the acceleration provided is impulsive in nature such as that resulting from a
shock wave. In this pedagogical review, we provide an extensive survey of the applications and examples where such
instabilities play a central role. First, fundamental aspects of the instabilities are reviewed including the underlying
flow physics at different stages of development, followed by an overview of analytical models describing the linear,
nonlinear and fully turbulent stages. RT and RM instabilities pose special challenges to numerical modeling, due to
the requirement that the sharp interface separating the fluids be captured with fidelity. These challenges are discussed
at length here, followed by a summary of the significant progress in recent years in addressing them. Examples of
the pivotal roles played by the instabilities in applications are given in the context of solar prominences, ionospheric
flows in space, supernovae, inertial fusion and pulsed-power experiments, pulsed detonation engines and scramjets.
Progress in our understanding of special cases of RT/RM instabilities is reviewed, including the effects of material
strength, chemical reactions, magnetic fields, as well as the roles the instabilities play in ejecta formation and transport, and explosively expanding flows. The article is addressed to a broad audience, but with particular attention to
graduate students and researchers that are interested in the state-of-the-art in our understanding of the instabilities and
the unique issues they present in the applications in which they are prominent.Science and Technology Facilities CouncilScience and Technology Facilities Counci
Wave Propagation
A wave is one of the basic physics phenomena observed by mankind since ancient time. The wave is also one of the most-studied physics phenomena that can be well described by mathematics. The study may be the best illustration of what is “science”, which approximates the laws of nature by using human defined symbols, operators, and languages. Having a good understanding of waves and wave propagation can help us to improve the quality of life and provide a pathway for future explorations of the nature and universe. This book introduces some exciting applications and theories to those who have general interests in waves and wave propagations, and provides insights and references to those who are specialized in the areas presented in the book
Abstracts on Radio Direction Finding (1899 - 1995)
The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography).
Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM.
The contents of these files are:
1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format];
2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format];
3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion
Physics through the 1990s: Plasmas and fluids
The volume contains recommendations for programs in, and government support of, plasma and fluid physics. Four broad areas are covered: the physics of fluids, general plasma physics, fusion, and space and astrophysical plasmas. In the first section, the accomplishments of fluid physics and a detailed review of its sub-fields, such as combustion, non-Newtonian fluids, turbulence, aerodynamics, and geophysical fluid dynamics, are described. The general plasma physics section deals with the wide scope of the theoretical concepts involved in plasma research, and with the machines; intense beam systems, collective and laser-driven accelerators, and the associated diagnostics. The section on the fusion plasma research program examines confinement and heating systems, such as Tokamaks, magnetic mirrors, and inertial-confinement systems, and several others. Finally, theory and experiment in space and astrophysical plasma research is detailed, ranging from the laboratory to the solar system and beyond. A glossary is included
Recommended from our members
Laboratory directed research and development. FY 1995 progress report
This document presents an overview of Laboratory Directed Research and Development Programs at Los Alamos. The nine technical disciplines in which research is described include materials, engineering and base technologies, plasma, fluids, and particle beams, chemistry, mathematics and computational science, atmic and molecular physics, geoscience, space science, and astrophysics, nuclear and particle physics, and biosciences. Brief descriptions are provided in the above programs
Numerical modelling of mesoscale atmospheric dispersion
Fall 1992.Includes bibliographical references
Recommended from our members
1997 international Sherwood fusion theory conference
Papers presented during the conference are indexed separately
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