How Does a Lumin/Plasma Disc Work?

[PenguinCo]

Hello,
I am familiar with how a plasma globe works, and there are plenty of resources describing them, but I'm not 100% sure how a plasma disc works.
If anyone knows, I'd love to have some insight on this subject.

Regards,

 

[Baluncore]

I believe that they work on the same principle. One has a spherical envelope, the other is a flat walled disc.

Since the envelope is filled at close to atmospheric pressure with a noble gas such as neon, there is no need for the spherical structure needed to enclose a vacuum. The manufacturing challenge with a disc comes when pumping out the air before replacing it with the noble gas.

 

[Mister Perfessor]

Yes I know it's an old thread. But I just thought it was a shame nobody cared enough to provide a solution. Who knows, maybe somebody else may come along looking for more information? I did, and this was only the 15th search result on the 1st page. I usually don't call it until at least 50 pages in...

But it seems to me there's a very well-established industry of dual paned insulated windows. Doesn't this speak to further insights?

Anyways, here's a few dumb ideas: One, you could try filling the space between panes with a liquid in order to purge the air, then blow the liquid back out using your noble gas. A hydrophobic coating on the glass might be useful for this. Two, you could seal the panes together with a flexible rubber ring that would allow temporarily collapsing the panes together while pumping the air out. Three, you can use a automatic-mixing epoxy gun inside a glovebox filled with the noble gas mixture to assemble a large batch of disks

I'm sure that if you actually do some research unlike myself, you may find much more practical advice on how to go about making plasma disks

 

[Baluncore]

Welcome to PF.
Those are not dumb ideas.

 

[Mister Perfessor]

Thanks. And, what about this: just how close together can the plates be & still work as a plasma discharge lightshow? Could one of the plates be used as the rear wall of an aquarium, to any useful effect? Could a upward facing plasma disk be used to influence the motion of a pendulum? Can a plasma discharge generate a magnetic field & thereby be utilized to affect the position of a compass needle?

 

[Baluncore]

just how close together can the plates be & still work as a plasma discharge lightshow?

That will depend on the cleanliness of the glass and the tendency for the discharge to burn a track on the inner surface.

Could one of the plates be used as the rear wall of an aquarium, to any useful effect?

Useful to whom? The discharge would probably not follow the fish because the water would discharge any external electric field. Maybe it would produce interesting florescence in the fish or algae. It might be more useful if you filled your double glazed windows with water, and fish.

Could a upward facing plasma disk be used to influence the motion of a pendulum?

Only through very small electrostatic effects due to charge induced on the outside of the plates. It is more likely that the pendulum would disturb the electric field and so change the path of the plasma discharge.

Can a plasma discharge generate a magnetic field & thereby be utilized to affect the position of a compass needle?

Every discharge generates a magnetic field. Where the discharge is driven by high frequency AC there will be no observable effect on a compass needle because the magnetic field is balanced AC, impressed on the Earth's much stronger magnetic field.

 

[Mister Perfessor]

I hadn't considered the cleanliness of the glass. But then, I haven't built these sort of things before

My original search was to find the same sort of answers like the OP's question on this thread. Ideally a website like Instructables. I suppose I should search that one directly

I'm getting the idea that established plasma sphere construction should be used for a guide in attempting to make a plasma disk. Power supply should be the same type & construction. Gases used should definitely be the same. Electrode material, the same. I would have to consider the sort of sealing material used at the outer edge of the disks might potentially contribute some contamination of the gas mixture? This would be one of the significant deviations from a sphere. I think it would also not be so good if the sealant was a good electrical conductor! My 1st choice at the moment without knowing more would be to try using Smooth-On's Solaris. With a 1" section of sealant, the breakdown voltage could be as high as 366,000 volts

I've noticed that the 'Lumin' plasma disks all have a very wide outer section of their disks which are filled with a sealer. This will likely be important for having enough dialectric thickness

 

[anorlunda]

I would have to consider the sort of sealing material used at the outer edge of the disks

Must you presume separate discs with seams? I can imagine starting with a glass plasma sphere, then heating it and flattening it into a pancake shape. No seams, no sealants.

Consult with your local friendly glass blower, or make a pilgrimage to Corning, New York.

 

[Mister Perfessor]

Must you presume separate discs with seams? I can imagine starting with a glass plasma sphere, then heating it and flattening it into a pancake shape. No seams, no sealants.

Consult with your local friendly glass blower, or make a pilgrimage to Corning, New York.

Oh yes, I must!

But that is an interesting alternate idea. Might even work better for some artistic applications I was considering

If you should happen to look at an example of the 'Lumin' plasma disk, you will see that they are using a pair of glass disks, bonded together. The OP's question was somewhat an investigation into how that particular approach is done

So far, I'm just guessing at how that was done. I don't actually know. But I have found a strange absence of DIY articles on how to make any sort of plasma disk, so I think that any discussion on any type of blog is better than what's been going on

It seems as if this is truly a dark art only meant for the Consumer Gods & chinese factories to know!