My biggest coil has a much higher power and throws big white hot sparks over a large area in this 8 second exposure. For more details and photos:
Above top shows some shots of the Tesla coil 18-inch diameter at higher power with a 3 foot rotating breakout point. Still not really firing well with strong 6 foot arcs and only occasional 7 and 8 foot weaker arcs. I didn’t try retuning or altering coupling and I suspect the quenching is still not right. It should be capable of better. Bottom right photo shows an 11 ft radius rotating point with sparks extending over about 27 feet. This was a step towards a shoot in a dome shaped building later in the year.
Above shows the coil in 2005 under early development, with a primary of magnet wire taped onto cardboard. If you look closely you can see Mars about ‘2 feet’ above the coil on the left.
The above photos were from a night shoot at the Gravity Discovery Center. Details here. The left photo shows the “Eye of Sauron” effect with the arc going directly to ground in a heavy power arc. But the spinning electrode is moving horizontally at 7 ft/sec. The ground arc is well formed it pulls an arc out from the top until it is nearly the same length again before it extinguishes and starts the process again. The power arcs are only 2-3 feet but the Tesla coil is running at 5-6 feet power. The middle photo shows the “triple 7” effect.
So why is the angle of the 7 so sharp? There are three competing forces. The main one is to stay in the hot ionized channel. Second is for the magnetic field effect to enlarge the angle outwards (think rail gun forces to push the arc out). This is counteracted by the electric fields encouraging the spark to take the shortest path.
It really is quite dramatic in action zap-stretch, zap-stretch.
The right photo again shows a full rotation which takes place in 7 seconds, perhaps 12 foot radius. It gives a whole march of about 40 “sevens”.
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Photo Date: 2007