Makeshift Arc Furnace

Idea:

The idea of an arc furnace is that if you put high amperage current through the air it will ionize the air. This not only produces huge amounts of heat, but it also allows for further current to be drawn through large distances (0-0.5inches) in the air at relatively low voltages (70V). The temperatures produced in the arc are over 2000F, while the amperages frequently melt the wire I use to wrap the transformer, I have not invested in proper transformer wire, and am instead just using standard ACE Hardware 10 gauge stranded wire. In general, this is a pretty unsafe project, but gloves, welding goggles and common sense have stopped me (so far) from having to use a fire extinguisher.
Though the copper wire can withstand the current and voltage, it cannot withstand the temperature of the arc. For that reason, I had to attach 40g graphite rods as anodes to the end of the wire. While these do vaporize when they are used, they do last for 7-10 minutes of use before decaying to the point of not being usable.

Statistics:

Transformer in: 120VAC at 15A (1800W)
Transformer out: ~70VAC at 25A
Estimated max arc length: 1/2 inches
Wire gauge: 10, stranded
Electrode material: Graphite

Those are all the interesting statistics I can think of, contact me if you wish to know anything else.

Images:

Direct image of 50g of melted copper (melting point: 1984F) sitting in a brick-made mold:

Video of full furnace heating crucible:

Conclusion:

This project was inspired by a video I found on youtube, by The King Of Random who showed me where to acquire the transformers (discarded microwave ovens), and generally how to wire them. The project did not provide the heat energy I was looking for, as it did not heat the full crucible much over 1000F, but it was quite educational. It has provided me with 3 microwave transformers allowing me to reach any voltage and amperage I could ever see needing (up to a theoretical 712,800VAC (chaining), and down to a theoretical 1800A (half wrap)).