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HV water bridge?

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LAN_403

Sulaiman

Wed Oct 03 2007, 03:02PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

WOW!

Please describe how the bridge was formed.

9kV/9mm = 1 kV/mm = WOW!

Alex

Wed Oct 03 2007, 03:45PM

Geometrically Frustrated
Registered Member #6 Joined: Thu Feb 02 2006, 04:18AM
Location: Bowdoin, Maine
Posts: 373

Wow, neat indeed. It would be very interesting if you could freeze it while the bridge was formed (or just try it at different temperatures, near freezing and near boiling, perhaps).

Experimentonomen

Wed Oct 03 2007, 04:54PM

Registered Member #941 Joined: Sun Aug 05 2007, 10:09AM
Location: in a swedish junk pile
Posts: 497

Better idea, video the bridge forming!

Tesladownunder

Wed Oct 03 2007, 08:41PM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

This was just a quick setup using my Sigma 180mm lens that does macros from 40cm away and might not be as clear on video. After all it is only a 1cm transparent event. I should try it though when I get time.
Drinking glasses are not ideal as water tends to get dragged over the edge and drip down. In the article they used beakers with a lip. I was eyeing off some cocktail glasses but my wife told me in no uncertain terms that these are not to be used in experiments.
In operation you start nearly touching and pull the glass away. To do this safely and without jerking I had the glass on a sheet of paper and pulled the paper. It was smooth and controlled.
As for the 1mm/kV I note they got up to 25mm with 25kV. Unfortunately my 80kV supply is out of action and my 100kV x-ray supply is buried so deep in the shed that I can't contemplate pulling it out.

Pic 1 is another shot which is shorter and shows a variation in thickness. This may have been due to vibration from waves in the glass. It appears to be a bit sensitive to wind currents.
I did wonder about attemting to freeze it with LN2 and presumably form a horizontal stalactite/mite. Problems might be the convective air currents, Also the fluid is apparently travelling across as well.

Pic 2 is of my shed and setup. The variac is just out of view. I used it to start at a lower voltage and build up as length progressed.

TDU

1191444071 10 FT32063 Hvwaterbridgeunstable

1191444071 10 FT32063 Hvwaterbridgefullview

Sulaiman

Wed Oct 03 2007, 08:56PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

I'm still amazed/enthralled,

do you know how much current is flowing through the bridge

i.e. is it worth trying with my 10 kV @ 1 mA hv dc supply?

Tesladownunder

Wed Oct 03 2007, 09:24PM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

The current is quite low so try it out. It should be fine. I haven't measured it though. This is the sparking without the water bridge. Almost invisible corona requiring a 30 second exposure for the picture below. This stuff is more about electrostatics than electric current.

Bill Beatty's site has info on the Wasserfedden (water-thread) effect. Apparently 100 years ago they used a Whimhurst static machine to provide the voltage. A small silk thread across the lips of the glasses provides the starter which then slides out when the flow starts. There is apparently two way flow through the bridge determind by putting dye in each side.

Edit: I've just seen a nearly identical thread started on the same day in the HV section.

TDU

1191446645 10 FT32063 Hvwaterbridgearcing

Dr. Dark Current

Thu Oct 04 2007, 08:14AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Do you need de-ionised/distilled water for this experiment or tap water is enough? I might try it with my 100kv dc flyback which runs at moderate power (cca 100w)

Tesladownunder

Thu Oct 04 2007, 09:01AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

Power is not a requirement since they originally ran on a static machine.
Distilled water is needed though but should be found in lots of places. Car battery topups need it and also domestic irons.
The bridge relies on electrostatic attraction rather than current flow.

TDU

Dr. Dark Current

Thu Oct 04 2007, 09:36AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

It does not work, the water just starts to boil in the point of contact, my distilled water is probably not enough distilled

(the bottle has been sitting for a year or so and has been previously opened)

But I've discovered another cool effect, with the glasses a few cm away, small water drops shoot from the positive glass at quite high speed towards the grounded one

Tesladownunder

Fri Oct 05 2007, 02:15AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

I seem to recall they used triple distilled water. I'm not sure how the analysis varies from deionised water which I use. Mst of the supermarket stuff is deionised.

TDU

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