On 5/19/15 3:09 AM, b alex pettit jr via Tesla wrote:
Hi All, I have a low powered TC that can produce arcs in the 2" to 8" range,secondary resonant freq 190 KHz. On any power setting, if I use a conductive rod to attract arcs ( sparks ) and space itto get individual, non branching arcs, there is surprisingly a consistent, repetitive pattern of brighter and darker ( fatter and thinner ) areas along its length.. Such as -------=========----------===---------------------------------------- Anyone have any ideas why this may be so ? I would have expected consistency,but there are arc segments with a brightness maybe 5 times the other portions. What is the propagation velocity of an arc in air ? This has been confirmed by others so it is not related to my 'visual acuity'.
What you see as a single spark is actually a lot of sparks following mostly the same paths. Not only is there a spark moving for each half cycle of the RF (way faster than you can see), but there's also multiple spark groups corresponding to the AC line voltage peaks.
When the sparks happen to align (or not) changes the apparent brightness.If you see a picture of a TC operating in a small movement of air, sometimes you see the different sparks (for AC line voltage cycles) spread out in parallel.
the other thing affecting apparent brightness is whether the spark is traveling exactly normal to the line of sight, or more aligned with it. This is really obvious when you are looking at a spark coming towards you: the spark segments that are exactly parallel to your line of sight look like really bright dots. Most people who have been in a "cage of death" faraday cage kind of situation have commented on this. I've tried to take a picture of it, but not been very successful: I think it's partly due to how the human visual system works in real time.
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