The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com Poulsen Arc Experiments:  Single 500T Pancake Coil Tests 11. Jan 2009 Setup:  500 turn 27 AWG Pancake Coil, roughly 6" OD, embedded in Paraffin Wax.  Half dozen primary turns of cloth covered house wire. Secondary has ca. 12 - 16 turns per layer, around 30 layers... Roughly 1/16" space wound between turns, 3 sheets of .010" thick 2" wide paper between layers... .032 Mica Condenser, Turpentine Copper-Graphite Spark Gap, MOT (Microwave Oven Transformer). Electromagnetic blowout coils are wound in series with each other and in series with the MOT to limit current.  They are wound with 21 AWG wire, 3/4" square laminated cores, wound on bakelite forms. Arrangement.  Gap in parallel with MOT output, 2kV, cap and Tesla Coil in series around the arc. Electromagnetic Blowouts, Copper and Graphite Electrodes (Graphite electrode cored with silk soaked in Turpentine) Ceramic insulators placed on wire next to gap.  (Thanks to Brian for those!) Appearance of Gap in operation Hot twisting ribbon sparks Accidental spark photo with flash