A plasma globe or plasma lamp (also called plasma ball, dome, sphere, tube or orb, depending on shape) is (usually) a clear glass sphere filled with a mixture of various noble gases with a high-voltage electrode in the center of the sphere. Plasma filaments extend from the inner electrode to the outer glass insulator, giving the appearance of multiple constant beams of colored light (see corona discharge and electric glow discharge). Plasma globes were most popular as novelty items in the 1980s.
The plasma lamp was invented by Nikola Tesla after his experimentation with high-frequency currents in an evacuated glass tube for the purpose of studying high voltage phenomena, but the modern versions were known to be first designed by Bill Parker. Tesla called this invention an inert gas discharge tube.
Plasma lamps are mainly used as curiosities or toys for their unique lighting effects and the "tricks" that can be performed on them by users moving their hands around them. They might also form part of a school's laboratory equipment for demonstration purposes. They are not usually employed for general lighting. However, as of recent years, some novelty stores have begun selling a nightlight plasma lamp that can fit into a standard light socket.