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Re: High speed Tesla spark photographs



Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>

Comments interspersed. A lot of this is cross posted to the 4HV forum thread on the same topic as well.
http://4hv.org/e107_plugins/forum/forum_viewtopic.php?15766.last

I am rather a noob in terms of camera knowledge but it looks like I will need to look at the RAW files being recorded separately. I do have a better understanding of unsharp masking now due to recent posts. I have a SanDisk Ultra II 1 gig Compact Flash card which is a fast version (or at least was last year) and needed for rapid photo sequences. Not sure that it helps the final image though. High speed cameras are great, but unless I win this one as a prize (like my current one), I am unlikely to ever get to use one. I am sure all of this stuff is trivial to people who have access to proper stuff and "know" physics. We (me anyway) are humble backyard experimenters just havin' fun .... I would like to get some better streamer shots but I have some "new" ideas that will be of even more interest, I think.

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
...
This is probably the most impressive Tesla coil spark photo I have ever seen!! ....

Flattery works for me :)  Thanks

It looks like the leader tip stalls a bit probably as that cycle reverses and cuts off the power. The next cycle reheats it and eventually it goes onward and briefly stalls again. ....

I don't think these are leader tips and my interpretation is a little different. What you have labelled as the leader tip on the left looks to me like a simple change in direction for the spark. In the two dimensions we see it in there is a sudden change in direction downwards. This will overlap the streamers and make that area bright. If the area is much brighter than expected (as it appears to be visually) then this is due to a third dimensional effect, ie the spark goes in or out of the plane of view for a distance which will relate to the perceived brightness. The second leader tip that you indicate on the right occurs where a streamer branches. Again there is streamer overlap. In both cases the streamer channel continues although all the 4 or 5 channels may be "stepped" so it looks like one or two were stopped. The diagrams from Bazelyan/Raizer, while not well labelled with time axes, indicate much faster events analysing what happens within the first strike that I just see as a single event.

Happily, I just got my mirrors in ;-))) A lot is going on the next few days, but I will see what I can get going!!

Great, don't let me have all the fun...

Cheers,

        Terry


Peter
http://tesladownunder.com/HighVoltage.htm#High%20speed%20Tesla%20spark%20photography