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Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sat Jan 02, 2010 5:55 pm
by Carl Willis
Hi Chris,

>It's driven by a 1kV potential. How fast do +1 ions get in a 1kV field? And what else would orbit at 4cm radius in a B=0.15T field?

The ions might reach 1 keV if they were formed at the center and made it to the cathode. If they are not found at the cathode radius, and did not originate at the center, then there's no reason to assume they are 1-keV ions. I was pointing out that this number is an assumption. As such, I do discourage putting too much credence in it.

>Is there some other way of doing the measurement you envisage?

I suggest setting this up with an oscilloscope that looks at the voltage drop across an appropriately-sized resistor in the power supply lead. Under voltage / pressure conditions where no steady-state discharge current flows, the transient current in the resistor is due electrode and wire capacitance when the sauce is turned on. Under conditions where the discharge forms, the current in the resistor would be the sum of the capacitive current previously measured, leakage current from the discharge, and current corresponding to the buildup of charge in the trap. The time integral of the trap-charging component would be a ballpark measure of trapped charge.

I can't be a backseat driver on such an experiment, I can't troubleshoot it, I can't guarantee it is easy or doable, I can only make the suggestion in general terms. The take-home message is simply that if you come up with a method of measuring trapped charge, that number would be infinitely preferable to assuming your design value by default.

I like the photos. It's a pretty discharge, and the magnetron is a fresh departure from the more-usual fusors and ion sources that fill the annals of this forum.

-Carl

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sat Jan 02, 2010 6:31 pm
by Chris Bradley
Carl Willis wrote:
> The ions might reach 1 keV if they were formed at the center and made it to the cathode. If they are not found at the cathode radius, and did not originate at the center, then there's no reason to assume they are 1-keV ions.
Indeed I agree not to make that assumption, but I hope, in due course, I will sufficiently explain to your satisfaction why ions formed anywhere in the device may attain that drive potential. And I repeat and reaffirm my caveats above - don't let me bias what you think at this stage.

Though - I would still be interested to hear your answer to this question; what else would orbit at 4cm radius in a B=0.15T field? Also, why else might we see such a structure?


> I was pointing out that this number is an assumption. As such, I do discourage putting too much credence in it.
I am currently looking to find a way [within my means] to disprove that it is so. It is not yet disproved.


> I suggest setting this up with an oscilloscope that looks at the voltage drop across an appropriately-sized resistor in the power supply lead. Under voltage / pressure conditions where no steady-state discharge current flows, the transient current in the resistor is due electrode and wire capacitance when the sauce is turned on. Under conditions where the discharge forms, the current in the resistor would be the sum of the capacitive current previously measured, leakage current from the discharge, and current corresponding to the buildup of charge in the trap. The time integral of the trap-charging component would be a ballpark measure of trapped charge.
I can do that. Not sure I quite understand why that is so definitive, but I will try to reconcile these measurements with this suggestion.


> I like the photos. It's a pretty discharge, and the magnetron is a fresh departure from the more-usual fusors and ion sources that fill the annals of this forum.
I'm glad, and I hope it's made your day (in particular!).

Again, to reaffirm my previous comments, I am not stating all that I could about this experiment just yet as I am unsure about much of it myself. This was [hopefully] just a 'spoiler' for things to come, and to get the year off on the right footing for the forum.

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sat Jan 02, 2010 7:35 pm
by Steven Sesselmann
Chris,

Congratulations on some fine work, nice to see some new ideas.

The picture in the above post, looks amazing, are the boundaries of the toroid as sharp as they look?

I can see a sharp red boundary, giving the impression that it is tube like.

Steven

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sat Jan 02, 2010 7:56 pm
by Chris Bradley

yes, generally this is what you see, but in the case of this last photo, you are looking down through a very straight part of this thing and so it is a little misleading. I took the pic just to show it wasn't a discharge in direct contact with the electrode, and at this particular point it followed the (flat) electrode, so you're looking through, as you say, a tube-like section of a few cm of the stuff.

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sat Jan 02, 2010 8:12 pm
by Chris Bradley
Carl Willis wrote:
> I suggest setting this up with an oscilloscope that looks at the voltage drop across an appropriately-sized resistor in the power supply lead. Under voltage / pressure conditions where no steady-state discharge current flows, the transient current in the resistor is due electrode and wire capacitance when the sauce is turned on. Under conditions where the discharge forms, the current in the resistor would be the sum of the capacitive current previously measured, leakage current from the discharge, and current corresponding to the buildup of charge in the trap. The time integral of the trap-charging component would be a ballpark measure of trapped charge.

I've just run what I thought was your suggestion but I'm not sure I really follow the applicability (now that I've done it).

At the highest pressures this thing appears at, around 20 microns, (above which you get both regular and 'odd' gas discharges, in my particular setup at the moment) the maximum current to which there is no visible thing happening, as measured by a DVM across a 470ohm load, is 6.8uA. The minimum current for which there is something visible is 7.7uA. Above that, the current will ramp up as much as you want unto >200uA when you start getting discharge modes again.

At the lower pressures of operation (around 1 micron), there is much the same delta but higher currents - with 9.7uA max current for nothing to appear and 11uA for the minimum current for something.

As I say, not sure this quite applies because (forgot to mention, amongst many other details) it appears you can set both voltage and limit current independently. A given voltage doesn't necessarily draw a given current, unless you permit it to, so it appears, which is again why I say it is not a discharge plasma. Not sure if that is a characteristic of my power supply, but basically you can dial in the voltage you want (within the range for which it works) then you can independently set the current limit, and it is quite happy and steady state is possible for a wide range of V and I settings. All that changes is the position, and the visible intensity, of the emissions. Whether there is some high frequency current switching going on unseen, I do not know, but it doesn't look like there is.

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sat Jan 02, 2010 10:17 pm
by DaveC
I don't want to be a "heavy" - here, but Chris - What is it that we are looking at? The pictures are very pretty.... I think from your discussion that you've built something that has a single central rod electrode ( that we can't really see) with four other electrodes arranged around the central axis, at some relatively small distance out from the central electrode. The space around all this is filled with a magnetic field established by permanent magnets (presumably) creating an axial magnetic field(?) of how strong, how uniform? The magnets are at ground potential (?) making some kind of radial electric field, which bumps around the rod cage.

Your explanation suggests that ions are produced by the four plus one central electrode assembly, which then circulate in the axial magnetic field. The ions do not recombine, per your explanation, but essentially produce molecular ionization (or excitation) of other neutrals, whose relaxation from their excited state is the source of the deep red glow we see???

Am I even close to understanding the experiment, you're doing?

A simple circuit and hardware diagram would go nicely here, to help appreciate all that's happening.

Did you say what the gas was? Deuterium, Oxygen, Hydrogen...or ???

Sorry to be a bit sluggish here.

Dave Cooper

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sun Jan 03, 2010 2:20 am
by Steven Sesselmann
Dave,

Chris has already answered many of the questions you ask in his prevoius posts. If you follow the links in the first post in this thread. Chris gives specific information about the magnetic field, and the assembly of the apparatus.

Steven

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sun Jan 03, 2010 3:28 am
by Quantum
Steven,

I think a lot of the confusion here arises from Chris's explanation of a design that originally consisted of magnets for confinement, then had five electrodes added, and is 'operating; in 'demo mode'(?), with magnets and electrodes, but will not have magnets in it's final form, so will consist of five electrodes.

Chris has often talked of combined magnetic/electrostatic confinement in the past, as being the key to improved efficiency in a fusor.

I think what Dave is asking for, and what would help a lot of people to follow this experiment, is a simple, brief explanation, with a 'diagram', of the method and objectives, rather than having to search through endless links to 'pick out' the relevant information.

In short, a 'brief summary',

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sun Jan 03, 2010 7:04 am
by Chris Bradley
Dave Cooper wrote:
> Am I even close to understanding the experiment, you're doing?

No, you're not close - you're bang on! Clearly I have said enough for you to comprehend it!

In regards the details of the conditions, as Steven says I have said all of this but will re-iterate these points so as to confirm them, and also add them to the extant 'summary' at the top:

Mag field = 0.15T, variation across device <5%, background; air, 1 to 20 microns controlled by a metered leak whilst running the turbo unthrottled (i.e. high through-put flow rates).

I guess I'm just concerned that the 'summary' might end up getting too long and someone will then want me to summarise the summary! This isn't a trivial experiment and has taken two years for me to get it all together (partly because I didn't know what it was supposed to look like!! - I have no plans to build to, I'm out on a limb here and 'winging it' as I go...).

You might begin to note that I have scattered the background to this amongst my posts over my 20 months of posting (yes, it's only been that long since I appeared here!). I guess about 30% of my posts directly or indirectly relate to this device, and I will create an anthology of those posts with some text to gel them together at some later stage, if it turns out to be worthwhile to do so. I was essentially aiming to provide background and build up understanding of my plans here these last 20mths before springing this on you, hence you will have to go rummage around if you want the fullest insight ahead of me creating a 'compiled works'!

On the matter of what I've set up for the e-fields: basically, I'm gonna flat out dodge the question! This is because I don't really know. I could say all that I am doing, but then that'd be another long post of speculated theory, and this was just to be some pretty pictures in Images du Jour. So please treat the subject of this thread as just that - mainly pretty pictures.

I've given a taster for where I think the theory sits just to give it sufficient context that they aren't abstract images, but as and when I have some level of ability to say with greater knowledge and insight than you, *then* I will discuss it further. For now, you may well guess better than me.

The reason that I'm not yet going to discuss what the e-fields are up to is because there are many many dielectric surfaces in this, some of which regularly break down (!) and therefore presumably many might be running in dark discharges without me noticiing. There is also plenty of electrode surface. So, taken altogether, I anticipate there are multiple sheath interactions and discharge processes going on which may dominate the e-field behaviour. I am therefore making many multiple alterations to the experiment to see what makes a difference and what those differences are. I don't think it is appropriate to speculate, then, beyond the most cursory 'working-explanation' of what we might be seeing in these photos.

I hope that properly gives the right level of 'caveat' coverage for now!

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sun Jan 03, 2010 3:07 pm
by Carl Willis
Hi Chris,

Well, the applicability would be to establish (A) that your magnetron does in fact trap some charge, (B) that it traps a particular quantity of charge, and (C) ultimately it would motivate scientific conclusions about particle density and circulating current along the lines of the numbers you came up with earlier by a daisy-chain of questionable assumptions.

What did your experiment entail, and what were the results? Are you able to capture a 'scope trace of the inrush current and post it?

For reference, attached is a figure from Greaves R., Phys. Rev. Letters 74, p. 90-93 (1995). The experiment has something to do with argon ions in a Penning trap, and they measure the trap filling by looking at the power supply current. The inset in the figure is a raw 'scope trace. The main figure is stored charge versus trap potential. For them, the kind of experiment I mentioned yielded useful data (though it has a lot of uncertainty as the error bars show). Your mileage may vary. This approach may not be useful in your situation.

-Carl

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sun Jan 03, 2010 3:12 pm
by Chris Bradley
Sure. That looks easily do-able.

So, is it the integration from baseline to peak, or to the knee of where it settles back down to the steady state loss.

Thanks for the suggestion. I'll get onto it.

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Mon Jan 04, 2010 6:35 pm
by DaveC
Chris -

Thanks for your confirmation. A detailed description of electric fields under plasma conditions is indeed difficult.

Dave Cooper

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Thu Jan 14, 2010 12:06 pm
by Chris Bradley
I have something to add in case it prompts anyone to pitch any new ideas on what is going on here (or alternative set-ups).

In the case of this experiment, and also of the images in download_thread.php?site=fusor&bn=fusor ... 1263249888 , I can say that I feel I chose wisely to construct a chamber that was fully lined by dielectrics. My latest round of experiments has been looking at holding various parts of the device at a fixed potential wrt ground. It turns out that if I do this then these plasma structures don't appear.

I've tried holding various parts at the external ground potential - tieing the +ve electrodes, the -ve, and even tieing the mid-points of parts, by a couple of multiMohm resistors. No substitute seems to permit these structures to develop.

This wasn't really my expectation...

What might this tell us? I guess it merely confuses the picture somewhat with additional complexity but perhaps some form of self-organisation is going on where the potential of the whole device, and thus the plasma in it, 'adjusts' itself wrt the potentials on the chamber surfaces. So I'm guessing here that the accumulation of charge might only occur if there is some surface charging going on around the assembly that finely balances the increasing potentials inside... or..?

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sun Jan 17, 2010 4:08 pm
by Chris Bradley
In the event that anyone looks at the above image and thinks 'hmm - that looks a bit vauge and blobby and I'm not sure it's circular', then I attach this image to show interesting discolouration patterns on the upper (and same on the lower) electrode after a number of various runs (and during a refit for a change of outer electrode topology).

Again, no specific observations but a few guesses might include electron irradiation from electrons being accelerated straight into the +ve plates (which would be parallel to mag field, so no consequent trapping and pretty much the only direction they can take) from the small background ionisation that would, presumably, be going on locally around the visible 'confinement' region.

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Mon Jan 25, 2010 5:58 pm
by Chris Bradley
I treated myself to a new DSLR today, particularly choosing one with a long 'bulb' capability on it to help image this work. (It is an Olympus e-600 which apparently has a bulb capability of 30 minutes! Me thinks I might out some astronomical imaging with it!!...)

I've added this image to the top post so that it can be compared directly to the first image. I allowed a little light into the room during the exposure to help make out some of the structures in the vessel. It differs slightly in that this configuration has a solid central electrode and I have replaced the outer electrodes with wire electrodes in this particular set up (they are the horizontal wires, which you can just make out in the background - there are two parallel horizontal wires at each electrode position where previously there were flat copper pieces).

.

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Thu Jul 01, 2010 4:43 am
by morgoth31
do you see a slight pinch where the other electrode are located?

Re: Archived - EXP: A New Year's treat; Crimzon doughnuts.

Posted: Thu Jul 01, 2010 9:25 am
by Hector
I like it. It's very original work in plasma physics. Never hurts to have some variety in the forum.

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sat Jul 03, 2010 2:18 pm
by Chris Bradley
I've observed nothing I would regard as pinching.

The 'torus' itself is somewhat squared off, so at the 'corners', there are some subtleties of geometry. It is like the shape you get in a Thomas cyclotron, where the azimuthal magnetic strength is varied in sectors. This is the same here - the magnets are at the corners and their flux passes through the upper and lower plates so as to even out the field throughout the volume, but this is somewhat imperfect and, unsurprisingly, there are azimuthal (and some radial) variations of magnetic field, but only by 10% or so. As the electric field is also varied at those 'exposed corners', so there is a basic change to any ExB behaviour there, and you get what you might describe as a characteristic 'Thomas angle' there.

I have yet to fully understand the interplay of electric and magnetic fields in this device (I've already evaded the question on electric fields, as above, and will continue to do so for a while until I feel I have confidence in my understanding of what I am doing) and the radius of the plasma glow region is affected by the geometry of the outer electrodes. I can cause a radius by changing the geometry and, as you might trivially expect, the further in is the plasma glow the more evenly toroidal it is, whereas the further out the more 'Thomas' shaped it is.

Whether you might argue the geometry becomes pinched at the corners, I wouldn't say at this time. I would tend to answer by being deliberately vauge (as I don't really know much better) and say that "there are configurations where the geometry of the plasma glow in the corners is anomalous". But in front of the electrodes, no, I have not noticed much but will be mindful to consider the question in future experiments.

Re: EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sun Jul 04, 2010 7:55 am
by morgoth31
point taken see what you mean.

just looked a pinched but yeah the field would be stronger right there.

i do love the look and feel of that its a very nice setup.

Re: Archived - EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sun Jul 04, 2010 8:20 am
by dbrown
Really like your chamber design and idea - hope you don't mind if I used the chamber design (not your approch to your problem!) some future day. A glass chamber looks great and your feed thru's are inspired.

Again, I know little about fusor's so can comment little on your physics but I will add one thing - remember, any statement you make must be based on fact, not speculation. It is your job to prove what you are speculating about is true. Speculation has its place and is good but that does not prove anything - only data does that. Still, good luck with your interesting idea.

Remember, we all make mistakes and don't worry about that nor take offense when people doubt what you say - that is how we learn and grow!

Re: Archived - EXP: A New Year's treat; Crimzon doughnuts.

Posted: Sun Jul 04, 2010 7:01 pm
by Chris Bradley
Dennis Brown wrote:
> I will add one thing - remember, any statement you make must be based on fact, not speculation. It is your job to prove what you are speculating about is true. Speculation has its place and is good but that does not prove anything - only data does that.

Well... personally I would only partly agree with such a statement. A statement that says "It Is So" should be backed up in an appropritate manner, but there is nothing in science that can be *proven* to be true. This is a false understanding of science.

For example, I'll ask you, if you don't mind, to *prove* the Sun will come up tomorrow. The reality is that you cannot *prove* it, but you can put forward a very convincing amount of evidence to suggest that it will be this way tomorrow. Modern science is based on the axiom that what we know works today will work tomorrow, and all that supports that observation is a dogmatic acceptance that it is so, based on an uninterrupted period where it has been shown to be true.

But this is just pontificating over the philosophy of science. In reality, I have never made any such statements that a thing "Is So" , but I have said "I consider that..." or "It appears that..". [If I have made such a statement, then it was only as shorthand for 'it is my opinion...']

Science is an accumulation of faith in repeatedly self-consistent outcomes (see "Bayesian probability"), and at some point, after something has happened enough times, it may become 'accepted' as being so.

In the case of this work, I said at the outset that there is little I want to say about it, other than putting up the pretty pictures and discussing some of the background, because there is not so much that I can confidently say about it at the moment.

Re: Archived - EXP: A New Year's treat; Crimzon doughnuts.

Posted: Mon Jul 05, 2010 10:09 pm
by dbrown
Prove the sun will come up?

OK, I'll agree with you that is a question that science can not do - wait, it can't prove that the next second will come or that jumping out the top window on a twenty story building will lead to your death since even gravity can not be proven to exist in absolute terms that we only use for religion - the thing called faith. But somehow, I'm sure I woun't (and I hope you) make the jump because it can't scientifically be proven to hurt you, must less kill yeah.

The issue is what we mean by science and that is the idea of empirical knowledge. Making statements about experiments require some support from data (and that others can repeat the experiment) - that is a fact and silly to argue or else we will endlessly try to prove the sun will come up tomorrow ... wait, how do you prove that it is the Earth that goes around the Sun, anyway? ... oops, that again.

Philosophy arguments can be fun and have their place but I would hope that here we will tend to prefer more serious discussions on this interesting topic of fusion and not these issues (but they are fun, too and do have a place.)

When someone makes strong speculation on an interesting topic without supporting empirical data (pictures are nice and informative, too but it doesn’t prove the ion types/orbits or other physics – don’t get me wrong, I like his results and think his results should be posted but also, strong statements need support so I hope they provide the data.) I thought the diffraction data and spectrum comparison was pure genius! And very good data.

However, here at this forum I agree that speculation has its place but so does accepting that others will not agree with your claims when they are speculative in nature and these people do not need to prove you wrong – it is your job to prove that you are right. That is the fun of experimental science (and it is science I hope we are doing here.)

Re: Archived - EXP: A New Year's treat; Crimzon doughnuts.

Posted: Tue Jul 06, 2010 2:28 am
by Chris Bradley
Dennis Brown wrote:
> The issue is what we mean by science and that is the idea of empirical knowledge.

> When someone makes strong speculation on an interesting topic without supporting empirical data (pictures are nice and informative, too but it doesn’t prove the ion types/orbits or other physics – don’t get me wrong,

A strong speculation? Perhaps your disagreement comes in deciding when a strong speculation requires supporting 'proof'. I agree a *statement* may require such a thing (if the caveats don't cover it as being axiomatic), but how can anyone make proprosals about what they are theorising if they aren't able to make 'strong speculations' without facts?

[It is my opinion and preference that an amateur effort should [and no doubt must] engage in speculations, else it will never be able to do anything more that repeat the prior work of academics. This is because if the only acceptable standard of evidence is 'full academic, and publishable' then it is not a standard we can be expected to achieve and so would end up limited to reconfirming the results of others because the path has already been trodden and the level of evidence so considerably lower, but pre-existing empirical material, that it is more engineering than science. But it is my preference to contemplate that which has not yet been done, whereas others here *do* find engagement in recreating the discoveries and findings of others, and do so very effectively at the highest levels. Perhaps part of this is that they are spared the sense of incorrigible audacity that grips some of us into thinking we can exceed what has gone before whereas they do not feel they are placed to exceed the research of academia. If you are only repeating prior work then there is no need to speculate about much.]

I will repeat what I said from the outset, and have reiterated;

"Now, please take on board that there is much I don't yet know about my own experiment. The work is ongoing. So whatever I might say about what I intended the experiment to do, what I think it does, &c., all of that might be wrong, and for now you will have to make up your own minds on what you're actually looking at. I will therefore be trying to say, and reply with, as little as possible so as not to bias your opinions of it."

..but being the open chap I am that likes to engage in discussion on things, I guess I may not have stuck to the last comment so well!!

As it happens, I do now have supporting evidence for some of the 'speculations' and will release it as 'evidence' once it is of sufficient and repeatable quality.

Re: Archived - EXP: A New Year's treat; Crimzon doughnuts.

Posted: Tue Jul 06, 2010 9:33 am
by dbrown
Please, speculate as needed! I didn't mean to say you shouldn’t - I just got the feeling that when someone challenged the speculation that this wasn't received so well. When speculating, you have to have a thick skin (I know all too well.) I was not trying to imply that there is anything wrong with speculation. That said, data and proof is best so others can review and use the information. This will, I feel, permit this great site to advance fusor's and keep people from associating this device with the cold fusion failures (which still appear to be based mostly on endless speculation - and to my surprise, just like the LLNL NIF (tragically).)

I really admire the dedication to good, well calibrate detectors and other aspects of data collection that the main guy's here do. I hope (someday, with luck and help from the great people here, to get near that level.)

Meantime, us less fortunate souls (without the great detectos), will also use speculation as needed, too.