MSimon wrote:Chris,
In a fusor the beams pass through the holes. Not all the holes have beams.
It's a good and interesting point and I do not pretend to have a known answer other than the electric fields are not uniform and also that once a beam starts up it will, specifically, ionise more material along ITS path and not another path.
The 'beam' is therefore self-ionising in that way - ions will run in from the point of their creation as it is formed, simply, where the beam is. The beams energy is lost to ionising event, and is therefore likely to be self-sustaining. Why selectively on particular beam directions? Because once a beam forms it will also generate an excess of electrons through which there are conductance losses, thus 'draining' the input power to feed the otherwise as yet unformed beams, and specifically in the direction of that beam, thus there will be a cascade of electrons in the first beam. More that one beam? Then they are better balanced than between another alterantive beam line.
Consider it as if it were a 'slow' form of lightning/HV tracking. These pick preferred routes also, and once the tracks are active, so they pull down all the current for themselves and surpress the power supply.
The experimenter might see a couple of beams form and cut off the current at that point. if the power had been upped, maybe more beams would form. Perhaps your question might equally be 'why do fusor experimenters only turn up the power to get one or two beams', the answer then being because they don't want ot burn the device out. So maybe we don't even actually understand the question well enough!!
Of course, you may be right, there may be a more complex reason that this that may touch on self-organisation. There are a lot of maybe-s between that and a $2M a year justification looking for it, just to prove a hunch.
I think you may choose that my explanation is insufficient because you are hoping for something more interesting than this - and that is you perogative to think like this on your own time and for your own interest, nothing wrong with that at all and good for you. But just be careful about the balance of evidence versus wishful thinking if you are trying to progress towards an 'optimum' understanding. I accept what you are saying as a possibility, sure. Does the evidence support further invesitgation based on your hunch..I am clearly less convinced than you are, but if it's your money then go for it!
best regards,
Chris MB.