it and into the 150 pF capacity, or capacitance, presented by an object, a conducting body, the size of a human. The filament is thinner because the magnetic fields around it, augmented by the now-higher current flowing through it, causes a magnetohydrodynamic effect called pinch: the plasma channel's own magnetic fields create a force acting to compress the size of the plasma channel itself. Much of the movement of the filaments is due to heating of the gas around the filament. When gas along the filament is heated, it becomes more buoyant and rises, carrying the filament with it. If the filament is discharging into a fixed object (like a hand) on the side of the ball, it will begin to deform into a curved path between the central electrode and the object. When the distance between the electrode and the object becomes too great to maintain, the filament will break and a new filament will reform between the electrode and the hand (see also Jacob's Ladder, which exhibits a similar behavior). An electric current is produced within any conductive object near the orb. The glass acts as a dielectric in a capacitor formed between the ionized gas and the hand. History In ("Incandescent Electric Light", 1894 February 6), Nikola Tesla describes a plasma lamp. This patent is for one of the first high-intensity discharge lamps. Tesla used an incandescent-type lamp ball with a single internal conductive element and excited the element with high voltage currents from a Tesla coil, thus creating the brush discharge emanation. He gained patent protection on a particular form of the lamp in which a light-giving small body or button of refractory material is supported by a conductor entering a very highly exhausted ball or receiver. Tesla called this invention the single terminal lamp, or, later, the "Inert Gas Discharge Tube". The Groundstar style of plasma ball was created by James Falk and marketed to collectors and science museums in the 1970s and 1980s. Jerry Pournelle in 1984 praised Orb Corporation's Omnisphere as "the most fabulous object in the entire world" and "magnificent ... a new kind of art object", stating "you can't buy mine for any price". The technology needed to formulate gas mixtures used in today's plasma spheres was not available to Tesla. Modern lamps typically use combinations of xenon, krypton and neon, although other gases can be used. These gas mixtures, along