On September 17th, I got a chance to see the world’s largest Tesla coil in operation at the Tesla Science Center at Wardenclyffe which is located in Shoreham, New York. As part of a belated birthday celebration of Nikola Tesla’s 166th birthday, which was on July 10th, Greg Leyh (@LightningOD on Twitter) operated his 40 ft tall Tesla coil in a spectacular and educational demonstration. The Tesla coil is a 1/3rd scale prototype for his endeavor to build two 121 ft tall Tesla coils. At his website, Lightning On Demand, you can read about the science behind this project and the objectives he hopes to achieve.
During the demonstration, Greg first had selected members of the audience hold onto fluorescent bulbs. He slowly raised the surrounding electric field by activating the coil and soon the bulbs lit up in their hands. Next he operated his own “Original Tesla Roadster” which used the invisible electric field to power a motor onboard the small “go kart sized” three wheeled buggy.
Turning things up a notch, Greg then demonstrated “Saint Elmo’s Fire” which is a cold corona discharge that occurs on pointed objects when the electric field reaches a certain breakdown threshold. These faint blue/purple arcs of light are cold streamers formed when that air ionizes without enough energy to cause significant thermal energy from kinetic collisions. The light comes from emissions during molecular and atom recombination or primarily nitrogen and oxygen after ionization or excitation to higher energy states.
He then demonstrated how these static discharges can ignite gasoline but not diesel fuel, followed by an impressive ignition of gun powder and hydrogen filled balloons.
Turning things up once again, Greg increased the voltage output of the Tesla coil and brilliant arcs finally began leaping from the Tesla coil itself as the air broke down under the electric stress produced by the tuned oscillators and coils. He zapped a long piece of wood which burst into flames as the power increased. His assistants then hoisted a human wood cutout holding an umbrella that had a covering of metal mesh spread out across its top. The Tesla coil struck the metal mesh which acted as a Faraday cage protecting the wood cutout below. After the metal mesh was removed, the arc did not hesitate to propagate down to the wood cutout burning a scar with ease.
I first met Greg in 2008 when he asked me if I could film his then smaller Tesla coils using my high-speed camera. I jumped at the opportunity and filmed them in action in San Francisco at recording speeds up to 66,000 images per second. The high-speed recordings, timelapes and integrated image stacks are below.
I learned then that Greg likes to run things until they break, and he did just that with his biggest coil in San Francisco. I suspected he would do the same at the Tesla Science Center, and sure enough he kept increasing the power to see what happens. Arcs shot up to the sky and down to the ground to the delight of all.