Explore #477 Jun 25, 2009
Taken at the CAMERA OBSCURA, EDINBURGH
These plasma balls have always fascinated me as a kid & great to see my kids just as fascinated. Just to actually feel the raw power beneath your fingertips divided by a millimetre thick dome of glass, you can actually hear the energy crackling within the dome !
A much smaller orb in its center serves as an electrode. Plasma filaments extend from the inner electrode to the outer glass insulator, giving the appearance of multiple constant beams of colored light . The beams initially follow the electric field lines of the dipole, but move upwards due to convection.
Placing a hand near the glass alters the high-frequency electric field causing a single beam to migrate from the inner ball to the point of contact. An electric current is produced within any conductive object near the orb, as the glass does not block the electromagnetic field created by the electric current flowing through the plasma (though the insulator does block the current itself).The glass acts as a dielectric in a capacitor formed between the ionized gas and the hand.
If you havent seen one of these before....put it on your Christmas list !