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Summary-Introduction: Collision-Free Plasmas(*)

Published online by Cambridge University Press:  19 March 2018

H. E. Petschek
H. E. Petschek*
Affiliation:
Avco-Everett Research Laboratory - Everett, Mass.

Extract

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In many cases, the outer atmosphere or corona regions of stars are not dominated by the ordinary process of collisions between ions. Very roughly, collision-free phenomena become of interest when the mean free path for interparticle collisions is larger than the region of space being considered. For solar corona conditions, if we consider a density of 107 particles per cubic centimeter and a typical particle velocity of 500 kilometer per second, the mean free path is a few times the solar diameter. At the same velocity for a density of 100 particles per cubic centimeter, corresponding to the interplanetary density, the mean free path would be a thousand astronomical units. Since in both of these regions, we are interested in smaller dimensions, it is of interest to consider the properties of a plasma in which collisions are very rare.

Information

Type
Part IV. Considerations on Localized Velocity Fields in Stellar Atmospheres: Prototype — The Solar Atmosphere
Information
Symposium - International Astronomical Union , Volume 12: Aerodynamic Phenomena in Stellar Atmospheres , 1960, pp. 448 - 458
Copyright
Copyright © Italian physical society 1960 

References

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