Videos of crimzon doughnut formation.

[Chris Bradley]

I've made a couple of videos to try help visualise what I've done in the other posts (viewtopic.php?f=18&t=7852#p55811)


http://www.youtube.com/watch?v=UoFGNb0evaA

to which I have put the following text: "This is showing the formation of a toroidal plasma structure. It is a Penning-type plasma in a new design of magnetron-type crossed-field configuration. In this clip, I am running only air into the device around the 1-10 micron range and slowly turning the drive voltage up and down with the aim that just the first few easiest-to-ionise ions/charged molecules form up first, so that they might be moderately well discriminated by q/m and so display a more obvious toroid. There is a magnetic field (0.15T) oriented vertical to the picture shown and there is a central electrode which is the vertical shadow left-of-centre which is surrounded by multiple electrodes some 60mm away and around it. The view is taken from behind and between two of the electrodes, and facing two electrode on the far side. At that pressure range of air, one can expect the chamber contents to be dominated by water molecules, so the Balmer-alpha colour might be expected to be highly dominant, which it appears to be. As the voltage is tweaked up and down in this clip, other ions will participate at higher voltages and the toroid would expect to become more diffused, which it does. The interesting feature of this that might allude to self-organisation is that I have formed a toroid at a lower pressure before ramping up to the conditions shown here and the toroid remains stable and 're-ignitable' simply on removal and reapplication of the electric fields, as can be seen. However, if the voltage is taken up high enough to cause an electrical breakdown, and a discharge plasma, then the toroid will not recover at this pressure. I am looking into this and considering the possibility that this feature is related to the fact that the chamber is all dielectric in construction and the toroid formation requires an evolving surface charge to control and oppose it as the space charge builds up. If this were true, then a discharge would disrupt that surface pattern of charging on the dielectric surfaces and the toroid would not reform, which is the case shown when, at the end, I cycle the voltage up to a point where a discharge occurs. The next video shows the behaviour of the toroid formation at a lower pressure, just at the point where a discharge is also possible."


and


http://www.youtube.com/watch?v=mAt4r7Etz-Q

to which I have put the covering text: "This clip shows a toroid forming at a critical pressure at which both discharge and toroid formations can occur. The central electrode is the vertical shadow to the right of the view. This view is in the plane of the toroid to show its vertical growth more clearly as the charge accumulates in the space. At higher pressures the toroid will not form, instead it only forms a discharge plasma (excepting, importantly, where a toroid has been formed at a lower pressure already and then the pressure slowly ramped up whilst the voltage is slowly ramped down so as to avoid a discharge occuring). At lower pressures, discharges do not occur and the toroid will form up readily. So at this pressure, where both can occur, I have set the conditions and drive voltages just at a critical point, and then left if. There are no adjustments being made to the drive voltage nor pressure in this clip. In the clip you can see the toroid forming up and as the charge density increases the toroid swells until it reaches a point where its potential can discharge to the outer electrodes. There is a discharge disruption, and then a 'new' toroid forms up. This repeats for as long as those conditions are maintained."


Feel free to let me know if you think I could improve the video material or the covering text.

[Doug Coulter]

Chris,
Nice eye candy. Would be better if you had a couple seconds in the front of the lights on so we could see the structure before there's enough self light in there to see it.

The covering text doesn't show up on the link, maybe I just don't know how to find it, or it's private to you, you might have to put it in as a comment. -- let me know, I'm setting up an account for fusor movies myself right about now myself.

Still looks like the gas pressure is way high and you are having cathode glow, which makes sense given the relatively low volts you're driving with -- at lower pressures where your idea should work, the voltages you are using would not start a glow at all, too long a mean free path. So you'll need an ion source or the like I think.

Keep up with this -- it's going to be good I think.

Doug

[Chris Bradley]

> Nice eye candy. Would be better if you had a couple seconds in the front of the lights on so we could see the structure before there's enough self light in there to see it.
I'll see what I can do, but I will have to hone some skills at video editing, I think!


> The covering text doesn't show up on the link, maybe I just don't know how to find it, or it's private to you, you might have to put it in as a comment. -- let me know, I'm setting up an account for fusor movies myself right about now myself.
You have to click the 'more info' in the top right. Alternatively, you can go to page;

http://www.youtube.com/user/crossedfields

and the format is easier to read when you link to the videos from there.


> Still looks like the gas pressure is way high and you are having cathode glow, which makes sense given the relatively low volts you're driving with -- at lower pressures where your idea should work, the voltages you are using would not start a glow at all, too long a mean free path. So you'll need an ion source or the like I think.
I guess you are saying that you can judge the pressures when the discharges occur, and then you see electrode glows. Yes, the pressure are quite high for where I would prefer to be in the parameter space. However....

I think I understand why you are saying this - if I were to put in 'fusing' voltages à la fusors, [10s of kV] then it would light up like an exploding firework factory. Agreed. However... bear in mind that in this configuration you end up with the, perhaps, non-intuitive outcome that the *lower* the voltage then the *higher* the max possible ion energy. Y'see, ions rotation speed are limited by Bq=mw so it is the B that defines their max energy. If I add in a dose of elctric field opposing the B field, then my w comes *down*, not go up. So *in theory* I want to generate this toroid at the lowest possible applied voltage so as to get the maximum 'benefit' out of the B field confinement. In theory I only need enough e-field to generate free ions that can then form into the plasma structures under the teasing guidance of those e-fields and the more brutal forces of the B fields. There are, however, consequences to a lower e-field and that is lower stability. If there was no efield, in extremis, then the ions would spiral off all over the chamber and be entirely un-confined - that is, if they had any energy at all. So there are trade-offs to using lower e field strengths.

I'm sorry if any of this sounds counter to understanding, vis-à-vis fusors, but that's what the maths decides for us!


> Keep up with this -- it's going to be good I think.
Thanks, Doug. Encouragement appreciated!

[Chris Bradley]

I have added an extra video clip;

http://www.youtube.com/watch?v=4_tbdZxm6dg

with the following description:

This is an alternative view of the device and plasma formation, as otherwise depicted in the other video clips. Here the camera is situated behind one of the electrode structures which obscures the central electrode but instead looks along one of the outer electrodes and across the horizontal plane. This means that the view of the plasma edge is, effectively, a tangent of the plasma structure. A small amount of natural light is present in the room to help the observer understand the orientation of the view. The outer electrodes are simply wires that have been secured to polycarbonate support 'plates' and the wires pass through holes drilled in those polycarbonate plates so that the only parts of the electrodes that face the plasma directly are as can be seen in the clip. In this clip a stable toroidally shaped plasma has been formed already, powered off, and the pressure increased. The applied potential is switched back on (with no intentional ramp, the power supply is simply turned back on) and the plasma structure can be seen to grow and swell until it actually envelopes the outer electrodes. I cannot say why, in this state, it doesn't actually cause a current discharge through the device, as in the other clip, but none is evident. I would initially speculate that, though the ions have moved into that region at power-on, the electrons that would be present (and which would move to try to neutralise the space charge those new ions create) are much more restricted in their horizontal movements through the device on account of the 0.15T vertically oriented field, and so there isn't and immediate conduction sufficient for a direct discharge at power-on. What can be seen, however, is that this plasma reaches the polycarbonate support and, after a short pause, retreats gradually back to its stable configuration as a toroidal-like plasma. You may need to watch it a couple of times to see this, but note how the plasma moves into, and illuminates, the area around the wire electrodes then gradually rolls back until at the end of the clip it is once again dark in that region.

[Doug Coulter]

Well, Chris, not exactly. I do agree on the relationship being tenuous between the operating conditions desired here and for normal fusors. But for pressure, a cyclotron-class thing runs at much lower pressure than any fusor for good operation, not more. Cyclotrons run at the edge, in a similar way to fusors where you have just enough gas to get ions, but not so much you have extra scattering. As the path length in a roundy round situation is far longer, for cyclotrons this usually means e-6 mbar and below, not ~1 mbar and up as I see there. Honest, just get to low pressure and see if things don't act a lot better and closer to your calculations, I think you'll get real happy at that point.

What I am saying is with that much gas pressure, your mean free path (another important math) is so short (fractions of a mm) your design isn't operating as stated either, and you won't get to energy with all the collisions with neutrals that will scatter things. Else I think we agree.

To run at decent mean free path pressures, you will have to provide a separate ion source, I think, at least at startup, after which it may (probably) become its own best ionizer anyway. You see this in fusors too. But if every ion has collisions with neutrals several times per roundy round, you're not going to get to energy, so you need to run at a low enough pressure for that to not be the main problem.

At the point you are seeing cathode glows with no visible dark space, your mean free path is very short indeed, you need to get a couple factors of 10 lower pressure, or so I think.

[Chris Bradley]

These tests are in the single-digit micron range, say e-4 to just touching e-2 mbar. Put it this way - it is just at the pressure where the PKR251 lights up the inverted magnetron gauge, so if that's working then presumably it's a pressure that 'magnetrons' work at!

I would not hold up too much reference between these and unmagnetised gas discharges, especially if you are drawing an erroneous conclusion that what you're looking at is 1mbar stuff. It doesn't appear to tie up at all. In the 1mbar range, I just get plain discharges all over the shop and up to the evacuation pipe/vac gauge. The feedthroughs and exposed conductors are 'moderately well covered' but not so well that they don't light up under such higher pressures. In these cases I get very obvious discharges as you suggest and they look quite different. In fact, I'll run it at a higher pressure and you'll see what I mean... Just consider how close those electrodes are to the magnetic yoke (which is held at the other potential) - if it were a 1mbar type discharge then it'd be drawing 10's to 100's mA, not uA as it is actually drawing.

For reasons beyond my complete understanding, once it is below the e-2mbar range, the 'external' discharges stop and I tend to get all the stuff going on inside the magnetic assembly.

I will say also that it is doing a lot of things unexpectedly and 'better than expected' so I am sure there is much to learn about what we don't know on this thing.

[Chris Bradley]

The pictures below show you the difference between what I am doing and what would happen at 1 mbar operating pressure. I've applied polarity both ways, just so you can judge against anything else you see. There is clearly no similarity between these images of applied voltage at 1 mbar, and the operating conditions for the videos.

[Richard Hull]

Magnetrons work at very deep vacuums. 10e-6 torr or thereabouts.

About the only thing on the planet that works near where you are working are neon signs.

Richard Hull

[Chris Bradley]

Richard Hull wrote:
> Magnetrons work at very deep vacuums. 10e-6 torr or thereabouts.
> About the only thing on the planet that works near where you are working are neon signs.
> Richard Hull
..and fusors??

Did you read where I explained it is operating at 1 to 10 microns?

[Carl Willis]

Hi Chris,

Thanks for the videos. Discharge phenomena are endlessly entertaining. They can be hard to explain, but easy to enjoy.

-Carl

[Richard Hull]

Chris was claiming a possible magnetron like activity at high pressures. This has yet to be shown of course and zero fusion in addition.

Carl said it correctly, and as I have long noted, gas discharge displays in the micron pressure ranges are endlessly fascinating and affords a vast range of electrode geometries. This discharging coupled with magnetics is even more intriguing. I have a lot of this type of activity in my first fusor video released back on 1999 with lots of interesting electrostatic breakdown phenomena as well. Fascinating, but no fusion.

My efforts in just studying ionic and electronic phenomena from 1997 to 1999 was to come to "own", at some core level, a "feeling" for many of the effects before proceeding to do the common fusion so easily achieved in a fusor.

Fusors do work in this pressure range by brute force and mass based, luck of the draw at pitiable efficiences with no hope of break even of advancing towards it in a realistic fashion. At any given moment in time, I doubt that more than two fusors are in operation on the surface of the planet. ( I would imagine that one might currently count the total working fusor population on earth by using only one's fingers and toes in the effort. Neon signage runs world wide 24/7 and are real useful systems numbering in the millions.

Glow systems abound. Fusion systems, from stellarators to tokamaks, to fusors, to NIF terawatt based systems all fall flat and are rare, indeed. They all fail to uncover anything new or a path towards useful fusion. The old adage about all the kings horses and all the kings men toiling in vain comes to mind.

We cannot even conceive of a realistically, realizable, continuously operational, day in, day out, fusion system that is even .0001 % efficient.

We can spin, herd and cajole ions and electrons in magnetic fields to our hearts content, bunching, crunching, stretching, and sausaging them, but power ready fusion just is not to be found there, it appears.

Richard Hull

[Chris Bradley]

Richard Hull wrote:
> Chris was claiming a possible magnetron like activity at high pressures. This has yet to be shown of course and zero fusion in addition.
Not sure I have yet strictly claimed anything at all. I have stated the intent, and the result is as the intent. That is all I think I have said.

All I can say is that fusion was never intended with this device, only a demonstration of the toroidal confinement principle, which it appears to have done eminently.

In fact, so eminently I ask; has a persistently confined, visible toroidal plasma with minimal input power and with no physical contact to the glow structure ever been imaged before?

You make such plasmas sound common place, but I've never seen such a thing.

In regards what the dynamics of the plasma is; there is a measured current of, say, typically 20uA. Using F=BIL across the visible width of that glow region, that'd be around 10nNm of torque resultant in that region. Where is that torque being reacted in that plasma, if it doesn't make stuff rotate?

[Carl Willis]

Chris, I see your videos and photos of a glow discharge that at times does seem to resemble a toroid.

About whether there is an "eminent" demonstration of a "toroidal confinement principle"...well, I wouldn't put it that way right now. There is a demonstration of a glow discharge that at times does seem to resemble a toroid. If the toroidal confinement principle is the one you mentioned earlier, namely, the magnetron principle, then there's room to do experiments and find if the results are consistent with it.

>Using F=BIL across the visible width of that glow region, that'd be around 10nNm of torque resultant in that region. Where is that torque being reacted in that plasma, if it doesn't make stuff rotate?

Is stuff rotating? Is the 20 uA flowing perpendicular to the magnetic fields in the apparatus?

-Carl

[Chris Bradley]

Carl Willis wrote:
> Is stuff rotating?

No idea.

> Is the 20 uA flowing perpendicular to the magnetic fields in the apparatus?

There are outer electrodes only at the mid-plane of the device, and there is a central electrode, and it pulls a current through those electrodes. So.. yes. Definitely.

[Kade]

Chris
are the end plates now isolated from the central electrode?

[Chris Bradley]

Unfortunately, no.

I say "unfortunately" because it was my original intention for it to be so and to try out some different configurations of voltages, but after I installed it all there was some continuity between the central electrode and the plates (I used little hand made rubber washers through the plates, which were, obviously, unsuccessful at good isolation) so I wired them together [externally] just to make sure I knew they were all at a consistent potential.

[Kade]

Chris,
I wonder then, if you may be able to install an insulated stud or surface on either the upper or lower end plate (positioned at about the radius of the toroid) that you could hold at either a positive potentional or a pulsing potential,. This may provide insight as to whether you do have rotating ions forming the toroid, and possibly some confirmation as to the frequency of rotation (using pulses may permitt you to view the wave length).
I may be off base but a small localised positive patch would be expected to cause a shift in the axial position locally in the toroid, which if the ions where actually rotating would potentially bounce a couple of times when moving back into the equilibrium position ( half way between the end plates) as the deflected ions rotate away from the localised potential discontinuity. if there was no rotation of ions and the toroid was simply a static "discharge ?" glow, I think that the equilibrium of position would not involve any dynamic phenomenon and would simply re-equalise as a function of distance from the patch electrode with no "ring" or "bounce".

-Kevin

[Chris Bradley]

I like the idea, if only to see what happens. Part of the reason I've not contemplated that before is that to separate upper and lower plates electrically will be a fundamental redesign. But that's why I post; to get all ideas in.

One technical issue to confound that, however, is that the visible formations are, I'm sure, not going to be just ions at this pressure but a plasma with a relatively small net potential. Only at the much lower pressures, where I can't actually see anything optically, would I expect such "pure" behaviour, though indirect detection by analysing the back EMF would seem a viable possible disgnostic means.

Thanks for the input.

[Frank Sanns]

Chris,

Remove one of your magnets. If the torus is there under three but not under the location where the one was removed then there is no rotation.

My intuition tells me there is no rotation and that this is just the shape of the plasma in the configuration you have made. What would the cause of any angular momentum in such a device since none of your fields are changing?

Frank Sanns

[Chris Bradley]

Frank, the mag field doesn't work like that. The flux from the magnets distrubutes itself throughout the volume. The setup is akin to a capacitor - attach a voltage source to a corner of the plates and the efield evens itself across those plates. There is a little "localisation" where the fields are close to saturation, but removing magnets asymmetrically doesn't create asymmetric fields, it just reduces the field strength.


Frank S. wrote:
> What would the cause of any angular momentum in such a device since none of your fields are changing?

ExB. It is a well understood principle. There is around 10nNm torque there, as measured by the magnetic field and current strength. That's one way of measuring torque in an eleectric machine; BIL.

[Kade]

Chris
Yes analysing the back EMF if you have some equipment would be a much better way to get a full story, especialy if you have a second stud or patch electrode positioned a bit around from the one used to input pertubations (could provide for calculating transfer functions).
I imagine if rotation is there, there would be a range of velociites through the radius (more like a free vortex than a forced vortex) and as such a pure result may not be expected as you said, but a frequency spectrum analyser may sort some of that out.