scholarly journals Theory of plasma transport induced by low-frequency hydromagnetic waves

1999 ◽  
Vol 104 (A2) ◽  
pp. 2421-2427 ◽  
Author(s):  
Liu Chen
Keyword(s):  
Low Frequency ◽  
Plasma Transport ◽  
Hydromagnetic Waves

Preferential acceleration of heavy ions from thermal velocities

1968 ◽  
Vol 46 (10) ◽  
pp. S638-S641 ◽  
Author(s):  
D. B. Melrose
Keyword(s):  
Frequency Spectrum ◽  
High Frequency ◽  
Heavy Ions ◽  
Crab Nebula ◽  
Low Frequency ◽  
High Frequency Waves ◽  
Hydromagnetic Waves ◽  
The Crab Nebula ◽  
Low Frequency Waves

The acceleration of ions from thermal velocities is analyzed to determine conditions under which heavy ions can be preferentially accelerated. Two accelerating mechanisms involving high-and low-frequency hydromagnetic waves respectively are considered. Preferential acceleration of heavy ions occurs for high-frequency waves if the frequency spectrum falls off faster than (frequency)−1. For the low-frequency waves heavy ions are less effectively accelerated than lighter ions. However, very heavy ions can be preferentially accelerated, the abundances of the very heavy ions being enhanced by a factor Ai over the thermal abundances. Acceleration of ions in the envelope of the Crab nebula is considered as an example.

Observations of ELF (extremely low frequency) signatures arising from space vehicle disturbances of the ionosphere

1991 ◽  
Vol 69 (8-9) ◽  
pp. 959-965 ◽  
Author(s):  
Jack Y. Dea ◽  
William Van Bise ◽  
Elizabeth A. Rauscher ◽  
Wolfgang-M. Boerner
Keyword(s):  
Geomagnetic Field ◽  
San Diego ◽  
Low Frequency ◽  
Space Vehicle ◽  
Lower Ionosphere ◽  
Space Vehicles ◽  
Extremely Low Frequency ◽  
Evanescent Fields ◽  
Hydromagnetic Waves

We report on observations of extremely low-frequency (ELF) signatures during exit or reentry of space vehicles through the ionosphere. The two modes regularly observed gave signals that peaked at 5.6 and 11.2 Hz. The evidence points to the lower ionosphere, i.e., the D- and E-layers, as the generator of these signals. The measurements were performed using ground-based multiturn coil sensors located in Reno and San Diego. The nature of these signals is unclear at present but it is surmised that we are detecting either the evanescent fields of hydromagnetic waves traveling in the ionosphere or the oscillating geomagnetic field associated with these hydromagnetic waves.

WAVES IN A RAREFIED IONIZED GAS PROPAGATED TRANSVERSE TO AN EXTERNAL MAGNETIC FIELD

1961 ◽  
Vol 39 (7) ◽  
pp. 1044-1057 ◽  
Author(s):  
Tomiya Watanabe
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Sound Waves ◽  
Ionized Gas ◽  
Frequency Limit ◽  
Electrons And Ions ◽  
Hydromagnetic Waves ◽  
Perturbed Magnetic Field

Waves being propagated in a rarefied and fully ionized gas and transverse to an external magnetic field have been studied, particularly hydromagnetic waves. Three modes of waves, in which the perturbed magnetic field is parallel to the external magnetic field, are found to be propagated. In a high-frequency limit, they tend to electromagnetic waves, electron sound waves, and ion sound waves. In the condition that the Alfvén velocity is greater than the ion sound velocity but smaller than the light velocity, the last mode tends to a hydromagnetic wave in the low-frequency limit. The other two modes of waves can be propagated only at frequencies higher than the critical frequencies, both of which almost equal the electron plasma frequency. The condition that hydromagnetic waves should be attenuated severely due to collisions between electrons and ions has been derived.

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