The secret is in the plasma.
The key component of a plasma converter is, effectively, an over-sized plasma torch. So naturally, in order to understand how a plasma converter works, one must first consider the inner workings of a plasma torch, and more importantly, the plasma itself.
The plasma torch can be simplified into two integral pieces: Compressed Gas & an Electric Arc.
(Image from: http://www.plasma-cutter.org/how_it_works.html)
When gas is forced through an electric current, some of that electricity is transfered to the gas. If the electric current is substantial enough, it will superheat the gas, causing it to ionize. In an ionized gas, electrons are not bound to their individual atoms, but instead flow freely within the gas. This highly energized gas is also known as plasma.
When plasma comes in contact with other forms of matter, it transfers the excess energy from itself to the material in question. ( http://www.allaboutcircuits.com/vol_3/chpt_13/9.html )
From a physics perspective, this is merely conservation of momentum in action. Heat can be simplified as vibrations on a sub-atomic level. This is where plasma does its work. As energy from these vibrations are transfered to materials, it actually causes the molecular bonds within the material to break apart.
This process is known as Molecular Disassociation and is the premise for plasma conversion technology.
Plasma can be observed all around us:
 The Sun is actually a giant ball of plasma and has been the source of all our energy for billions of years. |  Lightning is another form of naturally occurring plasma. The energy for lightning is built up as a static charge between particles in the clouds. The lightning bolt is really nothing more than a huge arc between the earth and the clouds. Just like in a plasma torch, the immense energy of the arc transfers to the air molecules, causing a momentary formation of plasma. |  Many applications for plasma exist and not all of them are destructive in nature. Fluorescent bulbs are filled with a plasma that produces little heat and lots of light. Even some toys use plasma to awe and inspire.  |
