| 1. |
- Alfvén, Hannes
(författare)
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Double-layers and circuits in astrophysics
- 1986
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Ingår i: IEEE Transactions on Plasma Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-3813 .- 1939-9375. ; 14:6, s. 779-793
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Tidskriftsartikel (refereegranskat)abstract
- As the rate of energy release in a double layer with voltage ΔV is P ≈ IΔV, a double layer must be treated as a part of a circuit which delivers the current I. As neither double layer nor circuit can be derived from magnetofluid models of a plasma, such models are useless for treating energy transfer by means of double layers. They must be replaced by particle models and circuit theory. A simple circuit is suggested which is applied to the energizing of auroral particles, to solar flares, and to intergalactic double radio sources. Application to the heliospheric current systems leads to the prediction of two double layers on the sun's axis which may give radiations detectable from Earth. Double layers in space should be classified as a new type of celestial object (one example is the double radio sources). It is tentatively suggested that X-ray and γ-ray bursts may be due to exploding double layers (although annihilation is an alternative energy source). A study of how a number of the most used textbooks in astrophysics treat important concepts such as double layers, critical velocity, pinch effects, and circuits is made. It is found that students using these textbooks remain essentially ignorant of even the existence of these concepts, despite the fact that some of them have been well known for half a century (e.g., double layers, Langmuir, 1929; pinch effect, Bennet, 1934).
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| 2. |
- Alfvén, Hannes
(författare)
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Model of the plasma universe
- 1986
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Ingår i: IEEE Transactions on Plasma Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-3813 .- 1939-9375. ; 14:6, s. 629-638
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Tidskriftsartikel (refereegranskat)abstract
- This paper is a review of a number of publications during the last ten years about those changes in our views of the cosmic environment that are the result of advances in plasma physics. To a large extent, these originate from new observational material that space research has supplied. An attempt is made to construct a model of the "plasma universe" which is claimed to be an alternative to the traditional " visual universe" based mainly on observations in the visual octave. Besides the Hubble expansion there is also a "knowledge expansion," which means that knowledge originating from plasma experiments in the laboratory is spreading to the magnetospheres and, it is predicted, sooner or later will also penetrate astrophysics in general. As an example of the usefulness of this model, it is applied to cosmogony, and a review is given of new results from an analysis of the Saturnian rings. The recent reconstruction of certain cosmogonic events with an accuracy better than 1 percent is reviewed and developed.
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| 3. |
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| 4. |
- Rothwell, P.L., et al.
(författare)
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A new model for auroral breakup during substorms
- 1989
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Ingår i: IEEE Transactions on Plasma Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-3813 .- 1939-9375. ; 17, s. 150-157
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Fälthammar, Carl-Gunne
(författare)
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Electric fields in the magnetosphere - the evidence from ISEE, GEOS, and Viking
- 1989
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Ingår i: IEEE Transactions on Plasma Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-3813. ; v, s. 174-185
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Tidskriftsartikel (refereegranskat)abstract
- Electric field measurements on the satellites GEOS-1, GEOS-2, ISEE-1, and Viking have extended the empirical knowledge of electric fields in space to include the outer regions of the magnetosphere. While the measurements confirm some of the theoretically expected properties of the electric fields, they also reveal unexpected features and a high degree of complexity and variability. The existence of a magnetospheric dawn-to-dusk electric field, as expected on the basis of extrapolation from low-altitude measurements, is confirmed in an average sense. However, the actual field exhibits large spatial and temporal variations, including strong fields of inductive origin. At the magnetopause, the average (dawn-to-dusk directed) tangential electric field component is typically obscured by irregular fluctuations of larger amplitude. In addition, data from electric-field measurements provide further support for the conclusion that a nonvanishing magnetic-field aligned electric field exists in the auroral acceleration region.
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