ThinkGeek’s shocking USB-powered Plasma Ball uses a “combination of interesting and fun gasses” to produce “some positively charged ions and a gorgeous gaseous and electrically conductive environment.” Video after the break. Click here for one more picture.
That high voltage served up through the electrode will now arc up through the plasma to the lower voltage edge of the plastic sphere (starting at the top where the temperature is greater). The arcs glow because they are hotter than the surrounding plasma. You can touch the plastic and the arcs will strongly congregate to your touch because you will be creating an even lower voltage jump from the electrode