Published on May 11, 2013
UPDATE 9/01/2014: New 21 centimetre fulgurite! Updated video: http://youtu.be/HWFCXNtWZEc
UPDATE 8/01/2014: I just beat my previous record of 19.5 centimetres with a fulgurite measuring 20 centimetres long! I shall post a video update soon.
UPDATE 26/10/2013: The longest fulgurite I have now made is 19.5 centimetres long, which is possibly a world record for artificial fulgurites. This narrowly beats the 19 centimetre fulgurite that Stefan, Toni, Daniel and Max from CapturedLightning.org made, using a 55kVA distribution transformer.
I will also try putting two MOT's in parallel and doubling the capacitance of my capacitor bank to get even longer fulgurites. The tip to success is more current and not so much voltage - 2,400 volts from my setup is plenty. However my setup does not supply quite enough amperage for my liking. I will post more updates soon.
Here I present my Artificial Fulgurite Forge, or: Fusing Sand with Electricity.
When lightning strikes sand, a hollow column of glass is left behind! These columns are called "fulgurites" (from Latin "Fulgor", meaning Thunder and also known as Petrified Lightning), and I will be making artificial fulgurites using a resonant MOT high voltage power supply. The supply consists of a single MOT (Microwave Oven Transformer) and two resonant HV capacitors. When short circuited, this supply can make high voltage plasma arcs 60cm long. When the arc is pulled through sand, the silica fuses to form a kind of glass. The molten glass is conductive, allowing the arc to be sustained. In this video I tested two types of silicous minerals: silicous soil and beach sand. The silicous soil is quite low purity, only about 90% Silicon dioxide. The rest consists of organic matter, charcoal, other minerals (notably Potassium carbonate, pumice and limestone), volcanic ash and sulfur (this kind of soil is evident of volcanic activity). Because of the organic matter and sulfur content, the soil is slightly flammable and drawing arcs gives off a terrible odour of sulfur dioxide. The longest fulgurites this material could yield was about 4cm. The beach sand, on the other hand, is completely unflammable, and very high purity (Over 99.9% SiO₂) with trace amounts of lime from shells. The fulgurite quality is substantially increased, with some fulgurites exceeding 16cm long. The fulgurites are also a much more appealing colour and texture.
Upcoming high voltage experiments that I am working on include making elemental silicon from a mixture of charcoal and sand, and making fulgurites from crushed Silica gel.
1 x Microwave Oven transformer. Supplies about 2100 volts AC, 0.5-1 amps short circuit current, but rated for 1000VA.
2 x Microwave Oven capacitor. Total; 2 microfarads (1uF each). Allows transformer resonant frequency to be 50Hz (New Zealand's line frequency). This is not quite resonant capacitance, but close enough. Increases voltage to about 2,400 and current to about 4 amps.
Outlet details: 240 volts, 10 amp breaker, 50Hz. Draws about 8 amps with capacitors (this has NEVER tripped the breaker). Without capacitors it draws 12 - 20 amps from mains and trips the breaker after about 10 seconds.
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