Plasma Sphere

A clear glass orb filled with a mixture of various noble gases (pressure inside 1-10 mm Hg) with a high-voltage electrode (5-10 kV and 30-100 kHz) in the centre of the sphere. Plasma filaments extend from the inner electrode to the outer glass insulator, giving the appearance of multiple constant beams of coloured light. Plasma is another state of matter besides gas, liquid and solid; in fact our Sun is made of plasma. Plasma sphere creates electro-magnetic field and that is why energy efficient bulb light up.

Plasma filaments drift from the centre of the sphere to surface because their density is smaller than density of the noble gas inside. When we put finger to the sphere we can observe higher density and brighter filament. This is because finger has electric potential 0 V (electric potential of the Earth) and the highest energy difference is between our finger and the central electrode.