| 1. |
- Fälthammar, Carl-Gunne, et al.
(författare)
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Magnetosphere-ionosphere interactions as a key to the plasma Univers
- 1995
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Ingår i: IEEE Transactions on Plasma Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-3813 .- 1939-9375. ; 23, s. 2-9
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Tidskriftsartikel (refereegranskat)abstract
- Almost all known matter in the universe is in a state, the plasma state, that is rare on Earth, and whose physical properties are still incompletely understood. Its complexity is such that a reliable understanding must build on empirical knowledge. While laboratory experiments are still an important source of such knowledge, Earth’s magnetospere-ionosphere system, made accessible by space technology, vastly widens the parameter ranges in which plasma phenomena can be studied. This system contains all three main categories of plasma present in the universe. Furthermore, the interaction between the magnetosphere and the ionosphere excites a wealth of plasma physical phenomena of fundamental importance. These include, among others, formation of magnetic-field aligned electric fields, acceleration of charged particles, release of magnetically stored energy, formation of filamentary and cellular structures, as well as unexpected chemical separation processes. What has been learned, and what stilt remains to be learned, from study of the magnetosphere-ionosphere system should therefore provide a much improved basis for understanding of our universe.
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| 2. |
- Fälthammar, Carl-Gunne
(författare)
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Plasma physics from laboratory to cosmos - The life and achievements of Hannes Alfven
- 1997
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Ingår i: IEEE Transactions on Plasma Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-3813 .- 1939-9375. ; 25, s. 409-414
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Tidskriftsartikel (refereegranskat)abstract
- Hannes Alfven, Lifetime Fellow of IEEE and 1970 Nobel Laureate for Physics, passed away on April 2, 1995 after a life of exceptional scientific achievement. His discoveries laid the foundations of major parts of modern plasma physics and its applications in areas as diverse as industrial processes, thermonuclear research, space physics, astrophysics, and cosmology. From a family background of high achievers and stimulating childhood experiences he went through an extremely rapid academic career, and his intense scientific activity lasted from his early twenties well into his eighties. His scientific work reveals a profound physical insight and an astounding intuition which allowed him to extract results of great importance and generality from specific problems. His most fundamental discoveries were those which opened a new field of physics, magnetohydrodynamics, and provided plasma physics with powerful new tools. His discovery of a new kind of waves, now called Alfven waves, was initially met with disbelief and accepted only years later. With the evolution of plasma physics, and especially space plasma physics, the significance of this discovery has grown to the extent that Alfven waves, and related terms such as Alfven velocity, Alfven number, etc., have become among the most frequently used terms in plasma physics. His introduction of the guiding center concept vastly simplified the analysis of charged particle motion in electric and magnetic fields and was the embryo from which grew the highly sophisticated adiabatic theory of particle motion. In addition to his most fundamental discoveries, Hannes Alfven made numerous important contributions to the physics of (what we now call) the magnetosphere, especially auroras and magnetic storms, as well as to solar and interplanetary physics, astrophysics, and cosmology. Often his contributions were initially disregarded or opposed but vindicated later, often as a result of new experiments in the laboratory or measurements in space. Some of his ideas remain unaccepted or controversial even today. Finally, it is worth emphasizing that Hannes Alfven contributed to the progress of science not only by his own work but also by the extraordinary inspiration that he gave to his many students as well as to colleagues all over the world.
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