Some old timers you can tell -- I ain't no spring chicken, and despite fast living, haven't died hard (yet). I think it's already past the point of leaving a good looking corpse. I'd guess Chris has some reason not to have put up a picture of himself as well (just kidding
). If pixels and computers don't mix well for him, he can always send me a photo and get me to do it!
LDX actually looks extremely complex to me, and superconductors right next to fusion -- as they say on Slashdot, "GoodLuckWithThat". I'd love to play with all that, but live kinda too far from a source of affordable cyrogenics (which might be true for everyone with that "affordable" qualifier).
I have no objection to using magnetic fields for things in general. However, they only affect moving particles and then only to make them tend to spiral around the lines. Containment is pretty iffy, as 100% or so of existing attempts seem to show, very roughly speaking. Directing and guiding seem wiser uses of that particular force, but I am willing to be shown a better way. Static containment just doesn't seem to actually work for anybody with H fields. Plasma is pretty snaky stuff...hard to handle at all, much less with a force that only ever acts normal to particle motions. I suppose the hope there is, that while two wrongs don't make a right, two rights can make a U turn.
As Chris points out, what is actually going on inside a plain old fusor is both complex and very poorly characterized in actuality. We have searched the literature widely for people measuring things I think might be important (like which polarity particles are going which way where, and how many, little things like that) and come up mostly a totally blank slate. Of course, if you go to fusor.net and ask "what are the rays" you'll get a number of opinions that is roughly twice the number of posters! And all of that is "it has to be" or "it oughta be" -- still no measurements.
I've learned to take that kind of armchair theorizing by people who only half-grasp an oversimplified version of the theory with a grain of salt, at best (this makes me unpopular in some places).
So, I determined to start grad school here, if you consider fusor.net grade school. Here we don't accept things because someone said so quite as much, and here it's also ok to out-do the teacher in your research, and in fact, encouraged. A saying I often use in sigs is "Why guess, when you can know,
measure it!".
It seems pretty obvious to me that nearly all the "theory" people come up with for fusors is in the class of "that's not even wrong", frankly. One example is recirculation -- why should that happen at all? I further tried to measure it and could detect none at all. I see the spring and the mass...that's a tuned circuit, not an oscillator. I measure a huge excess of electrons with a faraday probe that "armchair" theory says shouldn't be there, but it's there. And so on. Further, almost none of the fusor people (so far) have a clue about nearly a century of charged particle work in practical usage -- vacuum tubes. I think quite a lot of that can be valuable to us, but no one looks in the old books. After all, a proton acts pretty much like a heavier electron with the other sign of charge, as far as controlling them, making them flow and focus, all that. Here we have a more complex system -- both flavors of charge in a normal fusor, which allows for other things to creep in -- various emergent behavior, but that doesn't mean you first toss out existing knowledge before tackling the next step, at least, not to me. And in fact, I'm looking at approaches that simplify all this by getting rid of the electrons insofar as is possible. Well, that's my rant, yours is yours.
I would suspect that any dome that size you got affordable on E bay isn't quartz -- Ask MarkB what that would cost and the number of digits alone will amaze you. Probably 5 (used) or 6 (new) of those in base 10. You've probably got borosilicate, which is fine, actually. You will have to take measures to protect it, at least a metal screen with 100% coverage, or a metal box it sits over, otherwise it will break, and before that, it will be ruined by charged particle impacts and radiation. While being sputtered with metal from any charged electrodes in there. Even in my metal tank, I have to put a sacrificial glass piece inside the windows, and those pieces don't live many hours of operation before they become cracked and blackened. Just an FYI.
You'll get to glow with an NST, but nearly 100% of those are center-tapped with the center tap to ground, and it's real hard to change that. You can use one in a full wave CW multiplier to get the DC volts you need fairly well, especially if you resonate out the huge series inductance they have built in as a ballast, but that takes larger capacitor values than using a high frequency version. This won't help with the also huge series R they have built in of course. A 60 ma 15kv NST will only put out about 10 ma at 15kv (if you're lucky) -- the current is the short circuit current rating. Of course, if all you want is glow, AC is fine, and half of a big NST works very nicely -- it's what they were made for! The built in current limit is useful there while you learn.
You'll also get to glow with the nice Welch (I like those myself). But no one has gotten to really good fusion with just that. Sadly, most all fusors need to operate in a range a little better than any mech pump can get a real world chamber to, while a diffusion or turbo pump tends to be overkill and hard to control. You just can't get to pressure and purity requirements at the same time with just a mech pump in the presence of outgassing, one of those "sad but true" situations.
Everybody should have at least a plain old geiger counter (one with a thin window that can see alpha particles is good for other uses too). A real CD-V700 should do fine - It should be good enough to show you the cosmic ray background at a minimum, and most of those will (not the old super numb ion chambers though -- they only read awhile after you are dead). I strongly reccomend that it be hooked to some kind of audio output so you can hear it go, it's better and you can't ignore it or forget to check that way. Even my little survey meter has a little speaker and driver I added to it to hear the clicks, it's a super nice (and easy to add) feature. I used one transistor, a headphone speaker, and a 9v battery to make mine. This isn't so useful in detecting fusion, but it's kind of a mandatory safety device as when you have fusion, you're going to have X and gamma rays too, in general. In my system, almost as much energy goes to that as does to heat -- it's
loud. We'd like to keep you around!
In short, avoid the really old ion chamber/dosimeter type Civil Defense stuff. I put one of those nice dosimeters in a box with, well, hot rocks (Nuclear waste) that my scint counter sees from 10 feet away -- right through the lead walls -- and in a month, it finally just began to read at all. There's enough rads in that box to kill algae and cockroaches! And the ion chamber/meter says the box is cold. Yeah, right -- it utterly saturates a decent geiger counter with the lid off from about 3 feet -- this is one I keep outdoors! There are some nice parts to scavenge in these (an electrometer tube and some real high value resistors) but otherwise, it's a nice box to build something else into.
I'm using electron cyclotron resonance acceleration in a
microwave ion source I use here. I know at least Chris and I both think mere thermal energy cannot be the way to go, and got started discussing
a paper that shows why on another thread here. Basically it amounts to this -- thermalization means all the energy is split up into all the degrees of freedom, which is at least 3 for a proton (XYZ) and 6 for anything you can notice rotation on around those three axes. So 5/6 of the input energy is wasted, more or less. Further, it appears nearly all the losses are from various ways electron energy gets changed into photons, so if you had a choice (and I think you do) you'd just as soon not have them at all.