Published online by Cambridge University Press: 28 March 2006
The related questions concerning the transmission of electromagnetic waves are considered:
The reflexion and transmission of plane waves at a perfectly conducting layer of gas in an otherwise non-conducting atmosphere, when there is a uniform external magnetic field perpendicular to the layer. Here the main result is that a layer of finite depth h is an almost perfect filter, being transparent to waves of frequency nπA0/h (A0 = Alfvén velocity, n an integer).
The existence of plane surface waves for such a finite layer. There is always one such wave and, for certain ranges of frequency, two. The first becomes ‘choked’ at the filter frequencies, its velocity first tending to zero and then jumping to a finite value. The second chokes at the frequencies nπA0a0/h √(a20 + A20 (a0 = acoustic velocity).