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Yandersen

Thu Feb 21 2013, 10:27PM

Registered Member #6944 Joined: Fri Sept 28 2012, 04:54PM
Location: Canada
Posts: 340

Indeed! Plasma flare left a dark mark on the wire. So yes, arc does stretches very well. Will continue...
MrFlatox, where are the promised afternoon test shots? ;)

Yandersen

Fri Feb 22 2013, 12:51AM

Registered Member #6944 Joined: Fri Sept 28 2012, 04:54PM
Location: Canada
Posts: 340

So here is my current experimental setup:

The idea was to put electrodes and turns of a coil in the same plane, so plasma arc would experience force pulling it inside the tube (on the picture) stretching in a long flare.

The result seems to be desired, but actually there are no arc anymore - there are two glowing flares starting from each electrode and fading away in the desired direction, smoothly blurring (looks like two brushes). The ozone smell is very strong after the shot. The boom is very loud, even with a very small distance between electrodes - so the desired effect is actually achieved: the amount of air taking part in a process is increased, and electrodes are perfectly fine - melting is negligible.
Trying different inductances in series to limit the current has great effect on loudness of the BOOM. But those big turns of wire right on the accelerator should do the trick, I thought (Update: yeah, inductor is obsolete - BOOMs just fine without it, damper diode is fine).
I think I actually made an ion beam... Will play with it... Untill smg burn or blow... :)

Hmm, why ion beam? No... The glows I see with my eyes is just an ion recombination areas - places where different charges meet each other. All ions should actually make a weird circulations somewhere around electrodes: as soon as they got the same charge electrode has, they radially run away from it, and as a result of being in a magnetic field, ions start to circulate in the turns plane. The direction of flares is just dominant because of the attraction force ' perpendicular direction, so it does not mean there is an actual ion beam, I guess...

I did some modifications to the magnetic deflector and made my first video on YouTube to demonstrate the boom-boom thing:

(Have fun of my English, guys...)

MrFlatox

Fri Feb 22 2013, 11:29AM

Registered Member #9349 Joined: Mon Jan 07 2013, 08:50AM
Location: France
Posts: 102

waow ! That's uber interesting, could you detail a bit more the way you wind your electromagnet in the chamber ? I don't understand why it is wound that way. Very nice job.

Could we have more details on your triggering transformer too?

I promised fire, but I failed : I replace my poorly coupled air core transformer with a ferrite toroid one, and it does not produces any sparks at all now... I am interested in your triggering transformer setup as you seem to be using the same voltage as your main capacitor to power it up. I would like to do the same thing because having 30kV supply, capacitor, and sparkgap in the equation make things a bit messy to work around.

Edit : It would also be interesting to try your "guided plasma coil", but as my chamber is made of steel and brass, I guess this is a no go...

Ash Small

Fri Feb 22 2013, 12:07PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Yan, two related areas are 'Electron Cyclotron Resonance' and 'Z-Pinch'.

There is a thread here somewhere from just before christmas where Andy was trying to get spiral arcs using Z-pinch, I'll try to find some links later. I've only glanced at your posts as I don't have much time at the moment.

EDIT:

Yandersen wrote ...

cathode takes electrons from air molecules and negatively charged particles, anode gives electrons to positively charged particles and neutral atoms

This is actually incorrect. Electrons are emitted from the cathode. They travel to the anode.

The simple way to remember this is 'cathode ray tube' - the 'cathode ray' is an 'electron beam'.

EDIT 2: Here is the link to Andy's Z-pinch experiment:

EDIT 3: Link to Wikipedia page on Electron Cyclotron Resonance. In this case the wavelength would be equal to twice your pulse length, I assume.

Yandersen

Fri Feb 22 2013, 03:46PM

Registered Member #6944 Joined: Fri Sept 28 2012, 04:54PM
Location: Canada
Posts: 340

MrFlatox, the way I wound the coil around the discharge chamber may not be optimal so it may look messy. The idea was the following: if spark gap line and a turns of wire all lay in the same plane, then force which the ions traveling from one electrode to another experience is directed towards the wire (Lorenz force on charged particles) - this prevents ions from flying directly from one electrode to another forcing them to deflect and move around, hitting the other particles nerby, ionizing them and sharing kinetic energy achieved from acceleration by electric field. Here is the picture clearly showing the concept:

My transformer is made by winding a thick heavily insulated wire (22 turns, two wire pieces glued together) over a palm-size ferrite toroid. Primary has only 1 turn and triggering is done by connecting the 0.1uF@780V cap to that turn. You can do the same with your 400V, but add more turns to the secondary. I don't know if picture is of any use, but here is it:

MrFlatox

Fri Feb 22 2013, 04:37PM

Registered Member #9349 Joined: Mon Jan 07 2013, 08:50AM
Location: France
Posts: 102

Thank you for all those clear explanations !

Is the size of the ferrite torroid that important ? I only have small ones...

About your chamber coil, it doesn't look messy, it looks clever

Ash Small

Fri Feb 22 2013, 05:19PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

MrFlatox wrote ...

Is the size of the ferrite torroid that important ? I only have small ones...

You can stack several smaller cores, then wind around them all, as long as you have sufficient space for enough turns of thick wire.

Yandersen

Fri Feb 22 2013, 05:20PM

Registered Member #6944 Joined: Fri Sept 28 2012, 04:54PM
Location: Canada
Posts: 340

Size doesn't matter unless you need to fit hundred turns of thick heavily insulated wire. :)

MrFlatox

Fri Feb 22 2013, 05:38PM

Registered Member #9349 Joined: Mon Jan 07 2013, 08:50AM
Location: France
Posts: 102

Is there a polarity to respect when doing making such a transformer ?

Edit : Would a TV flyback ferrite core work ? I have plenty of thoses laying around, and it has better clearance for wiring.

Yandersen

Fri Feb 22 2013, 07:39PM

Registered Member #6944 Joined: Fri Sept 28 2012, 04:54PM
Location: Canada
Posts: 340

Oh, that would be even better than perfect!
I did not tried to reverse polarity and see the difference, but logically, it should matter. But from the other hand, connecting cap to the primary should create oscillating circuit, so polarity will reverse anyway.

I tried a circular discharger, which works perfectly fine and takes less space:

I think, if non-conductive barrel used, this discharger can be done in the following way:
nail in the center as one electrode, ring around as another electrode, non-conductive pipe encapsulating those electrodes in a closed space (the chamber), and a wire wound around the chamber outside the pipe as inductor and magnetizing coil at the same time. Should work the same way - try.

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