This thread really follows on from "The Secret of Sonoluminescence" thread. Any Vort coming new to this post really ought to read "The Secret..." first in order to properly follow the argument.
For anyone not familiar with the workings of a cavity magnetron, there is a very clear article on it at the following URL. http://www.ieee-virtual-museum.org/collection/tech.php?id=2345892&lid=1 In particular, it is well worth while firing up the animation half way down the page. This gives a very good visual appreciation of what is going on. Interestingly enough the other night I was watching a programme on Michael Faraday (whose house I pass by every Sunday morning). The programme presented a dramatisation of his discovery of the electric motor where a wire rotates around the pole of a vertical magnet in a pool of mercury. Seeing the animation of the electrons circling round the magnetic field in the cavity magnetron immediately brought Faraday's historic experiment to mind. The IEEE animation of the magnetron's operation states, ============================================== It works somewhat like a whistle. Wind blown over a bottle excites the air inside sending off sound waves at a wavelength dependent on the size of the cavity. Tipped on its side the bottle opening resembles one of the 8 cavities in a cavity magnetron. In a cavity magnetron, however, instead of wind, electrons form a propeller-shaped cloud and pass rapidly over the cavity openings, exciting them. Instead of sound, short radio waves called microwaves are generated at a wavelength set by the size of the cavities. ============================================== Now the following paragraphs appear in the main body of the article. ======================================================= By 1939, other researchers had discovered that under certain conditions, the magnetron could produce very high-frequency radio waves. Boot and Randall decided to construct a magnetron that could handle a lot of power and generate microwaves efficiently. Most electron tubes at that time used glass envelopes to enclose the evacuated space inside of the device. Instead of glass, Boot and Randall made their magnetron tube enclosure out of a solid block of copper, which conducts heat very well. In order to tune the tubes output wavelength efficiently, they drilled special holes called cavities into the block. Just as the length of an organ pipe tunes the pipe to a certain pitch, the size of a magnetrons cavities can efficiently tune microwaves to a certain wavelength. Then Boot and Randall put the entire tube into a strong magnetic field that swept electrons past the cavities in a rotary motion. In February of 1940, the English researchers tested their first working cavity magnetron. They were amazed to find that it produced over 400 watts of power at the extremely short wavelength of 9.8 cm (about 4 inches). This was nearly a hundred times more power than anyone else had ever produced at that wavelength. ========================================================== Now ask yourself the question. Why were the Boot and Randall so amazed to find that it produced "a hundred times more power than anyone else had ever produced" ? They were amazed because they didn't realise that the above two paragraphs that accompany the animation are a perfect description of what is going on in an Atmosphere at a pressure undreamt of in their wildest imaginings. What atmosphere? The Beta-atmosphere, obviously. Rewriting the animation paragraphs in the light of this insight gives us, ============================================== It works somewhat like a whistle. Wind blown over a bottle excites the Alpha-atmosphere inside sending off sound waves at a wavelength dependent on the size of the cavity. Tipped on its side the bottle opening resembles one of the 8 cavities in a cavity magnetron. In a cavity magnetron, however, instead of Alpha-atmosphere wind, electrons manifest a Beta-atmosphere wind which passes rapidly over the cavity openings, exciting them. Instead of Alpha-atmosphere sound waves, Beta-atmosphere invisible light waves called microwaves are generated at a wavelength set by the size of the cavities. ============================================== Now, to me, that interpretation of what is going on is obviously right. But then I've been working with the concept of a Beta-atmosphere for decades so it's relatively easy for me to realise when a piece of the jigsaw fits. It will be interesting to find out if anyone else can see what I have seen. Cheers, Frank Grimer ======================== in principio erat Verbum et lux in tenebris lucet ========================
