Welcome
Username or Email:

Password:


Missing Code




[ ]
[ ]
Online
  • Guests: 22
  • Members: 0
  • Newest Member: omjtest
  • Most ever online: 396
    Guests: 396, Members: 0 on 12 Jan : 12:51
Members Birthdays:
One birthday today, congrats!
uzzors2k (35)


Next birthdays
03/29 GrantX (34)
03/30 Adam Horden (39)
03/30 Mr.Warwickshire (23)
Contact
If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.


Special Thanks To:
  • Aaron Holmes
  • Aaron Wheeler
  • Adam Horden
  • Alan Scrimgeour
  • Andre
  • Andrew Haynes
  • Anonymous000
  • asabase
  • Austin Weil
  • barney
  • Barry
  • Bert Hickman
  • Bill Kukowski
  • Blitzorn
  • Brandon Paradelas
  • Bruce Bowling
  • BubeeMike
  • Byong Park
  • Cesiumsponge
  • Chris F.
  • Chris Hooper
  • Corey Worthington
  • Derek Woodroffe
  • Dalus
  • Dan Strother
  • Daniel Davis
  • Daniel Uhrenholt
  • datasheetarchive
  • Dave Billington
  • Dave Marshall
  • David F.
  • Dennis Rogers
  • drelectrix
  • Dr. John Gudenas
  • Dr. Spark
  • E.TexasTesla
  • eastvoltresearch
  • Eirik Taylor
  • Erik Dyakov
  • Erlend^SE
  • Finn Hammer
  • Firebug24k
  • GalliumMan
  • Gary Peterson
  • George Slade
  • GhostNull
  • Gordon Mcknight
  • Graham Armitage
  • Grant
  • GreySoul
  • Henry H
  • IamSmooth
  • In memory of Leo Powning
  • Jacob Cash
  • James Howells
  • James Pawson
  • Jeff Greenfield
  • Jeff Thomas
  • Jesse Frost
  • Jim Mitchell
  • jlr134
  • Joe Mastroianni
  • John Forcina
  • John Oberg
  • John Willcutt
  • Jon Newcomb
  • klugesmith
  • Leslie Wright
  • Lutz Hoffman
  • Mads Barnkob
  • Martin King
  • Mats Karlsson
  • Matt Gibson
  • Matthew Guidry
  • mbd
  • Michael D'Angelo
  • Mikkel
  • mileswaldron
  • mister_rf
  • Neil Foster
  • Nick de Smith
  • Nick Soroka
  • nicklenorp
  • Nik
  • Norman Stanley
  • Patrick Coleman
  • Paul Brodie
  • Paul Jordan
  • Paul Montgomery
  • Ped
  • Peter Krogen
  • Peter Terren
  • PhilGood
  • Richard Feldman
  • Robert Bush
  • Royce Bailey
  • Scott Fusare
  • Scott Newman
  • smiffy
  • Stella
  • Steven Busic
  • Steve Conner
  • Steve Jones
  • Steve Ward
  • Sulaiman
  • Thomas Coyle
  • Thomas A. Wallace
  • Thomas W
  • Timo
  • Torch
  • Ulf Jonsson
  • vasil
  • Vaxian
  • vladi mazzilli
  • wastehl
  • Weston
  • William Kim
  • William N.
  • William Stehl
  • Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Forums
4hv.org :: Forums :: High Voltage
« Previous topic | Next topic »   

High speed spark photography

Move Thread LAN_403
Tesladownunder
Tue Sept 05 2006, 02:48PM
Tesladownunder Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424
This sort of follows on from the thead about End-on and broken sparks but has drifted into a new field for me. Here I look at spark photography in a rotating mirror particularly to examine the area of discontinuity frequently seen at the negative end of low intensity DC sparks.

Now this is interesting. This is taken through a rotating mirror. I joined a first surface laser mirror to one of my motors. Running at 2250RPM and with the spark 16cm away the radial velocity of the spark is 37m/s. With the image being only the negative 2cm of a total 7cm spark width, the vertical distance the same as the width of the spark is 500us. So you should see events in the region of 10us easily enough. There doesn't seem to be any structure at that level around the discontinuity.

Of course, with each spark lasting microseconds or less it becomes harder to catch a spark in the mirror. Even with 2 second exposures and the spark firing at perhaps 20Hz you only get a spark in view occasionally.

It should be easy to increase the resolution by a factor of 10 - 20 to see events at microsecond level. It may take many minutes of exposure to get a spark though.
This would be of great interest to Tesla coiling to get sparks seen on that time frame.

Note that this is not a true high speed photograph. Vertical movement of the spark on the image may be due to irregularity of the spark or due to events happening in time. Multiple spark channels should show up well or stepped leaders perhaps.

Peter

1157467707 10 FT0 Hvbrokensparksrotatingmirror1
Back to top
Bjørn
Tue Sept 05 2006, 04:12PM
Bjørn Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
Do you have the .NEF RAW file?
Back to top
Tesladownunder
Tue Sept 05 2006, 06:39PM
Tesladownunder Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424
I don't have software to manipulate the RAW files (I think) so I haven't set up to save pics as RAW.

I could try another camera but pics will be low quality compared to the Nikon.

Some other fast pics with 500us Vertical scale. There were a few partial shots where the spark is only seen one one side. I thought that this might have been end of shutter travel effects, however two examples on one shot make this unlikely. Could this be spark growth from a positive leader? This was seen several times.

The last two are slower pics at only 94RPM ie vertical scale is 12ms. My interpretation of the blur on the last pic is the ionization fading away after the spark ceases.

Peter

1157481592 10 FT15720 Hvbrokensparksrotatingmirrorpartial

1157481592 10 FT15720 Hvbrokensparksrotatingmirrorpartial2

1157481592 10 FT15720 Hvbrokensparksrotatingmirror2

1157481592 10 FT15720 Hvbrokensparksrotatingmirror12msvert
Back to top
Terry Fritz
Sat Sept 09 2006, 02:09AM
Terry Fritz Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297
Hi TDU,

I am thinking of something like this:

Link2

The camera is just mounted to a base. A small square block is machined "well" and has four mirrors glued to its faces. Two 20,000 RPM hobby car motors spin it like mad. A lexan shild protects the camera if it gives way. I can mill the block to 0.001 inch and all so I think it will not tear up cry

At 20,000 RPM, the angulare velocity of the image is really double to 40,000 x 360 degrees per minute or 1 degree every 4uS wink At say 8 feet that is 0.4 inch per uS or 4 inches per cycle for a 100kHz coil!!! Should work!!

Easy just to use two motors for mounting since another motor is simple and cheap like the Mabuchi Speed-550 here for $10...

Link2

Edmund has the mirrors:

Link2

Should be very easy to do and should work well I think. My old digital camera has manual focus too. Glad I paid $800 for it amazed I even got it to work with Windows XP!! So I think it is a "go" cheesey

Cheers,

Terry
Back to top
Tesladownunder
Sat Sept 09 2006, 03:46AM
Tesladownunder Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424
I was previously thinking that better resolution would be obtained at a greater distance. This of course only happens while your camera can enlarge the image to fit the feature size in the full screen. After that no benefit. By analogy 1 degree is millions of miles at the orbit of our most recently excommunicated planet, Pluto but if you can't focus a full screen there, forget it.
Accepting that means I get clearer pics and easier focus to make things full screen. Here is 100kHz with reasonable detail of the LED internals.
1157773575 10 FT15720 Hvbrokensparkledcalibrate100khz
Back to top
Terry Fritz
Sat Sept 09 2006, 04:25AM
Terry Fritz Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297
Here is 100kHz with reasonable detail of the LED internals


Wow cool!! Are you able to focus your setup on a Tesla coil?

Maybe I don't have to bother. Although it would be a cool toy to have wink)

My cam has nice focus and zoom manual adjustments. I will have to figure them out wink)

Cheers,

Terry
Back to top
Tesladownunder
Sun Sept 10 2006, 06:49AM
Tesladownunder Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424
The weather is not the best for my TC at present but here is a pic of a Royer ZVS circuit firing a rewound inverter MOT transformer to give perhaps 2kV at 15kHz. It wasn't bright enough to show so I had to use a diode, resistor and .06uF Mica Cap to give a brighter spark which was rather irregular due to the low firing voltage.

Pic shows the setup before I added the cap. Second pic is 100 vertical pixels = 10us showing 3 sparks of less then 1us duration, which appear to deviate from a vertical line. Going back to the setup photo, you can see that one of the electrodes is vibrating changing the spark position.
The 3 sparks suggest that there is a resonance at about 10us period - 100kHz due to the .06uF cap and the effective series inductance of the cap itself plus the two 8 inch crocodile clip leads.

As you can judge by the pixellation (automatically smoothed by the software) plus the noise, the camera is being pushed to the limit. Very small sparks still seem to be point events. Hopefully a 2 foot TC spark will have more structure.

To see speed of light events I would need to have 500 foot events which would be 1us. In fact it would not be too hard to bounce a laser over a path this length to show the speed of light. Hmmm... I have a corner cube prism and two eight inch parallel first surface mirrors. Add a beam splitter or two, line it all up and go. Ohh, and it needs to have picosecond switching. Did I mention that sad Maybe my scanner Hex mirror assembly could rotate the laser beam to give fast enough effective switching. Head is starting to hurt here.


Peter

1157870971 10 FT15720 Hvrotmirrorroyer2kvdctransformerview

Back to top

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob

Go to:

Powered by e107 Forum System
 
Legal Information
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.