Definition A plasma globe, also known as a plasma ball, plasma lamp, or plasma sphere, is a sealed glass container filled with a mixture of noble gases and ionized by a high-voltage electrode at its center, producing branching filaments of colored light that resemble electric arcs.
Overview Plasma globes are commonly used for educational and decorative purposes. They demonstrate principles of electrical conductivity, ionization, and plasma physics in a visually engaging manner. When a person touches the surface of the globe, the filaments of light concentrate toward the point of contact due to the conductivity of the human body, which provides a preferred path to ground for the electrical currents. These devices are typically powered by several thousand volts at high frequency, usually generated by a Tesla coil-like circuit inside the base.
Etymology/Origin The term "plasma globe" combines "plasma," referring to the fourth state of matter (ionized gas), with "globe," describing its spherical shape. The device was invented by Nikola Tesla in the 1890s, who experimented with high-frequency currents in evacuated glass tubes. However, the modern version popularized as a novelty item was developed in the 1970s by James Falk and Bill Parker during their studies at MIT.
Characteristics
- The central electrode emits high-frequency alternating current, typically in the range of 2–5 kV at frequencies around 20–50 kHz.
- The globe is filled with noble gases such as neon, argon, xenon, or krypton, at low pressure.
- The ionized gas forms glowing plasma filaments that extend from the center to the inner glass surface.
- The colors of the filaments depend on the types of gases used; for example, neon produces reddish-orange hues, while xenon yields blue or purple.
- The filaments respond to external conductive objects, such as a hand, due to capacitive coupling.
Related Topics
- Plasma (physics)
- Noble gases
- Ionization
- High-voltage electronics
- Tesla coil
- Gas-discharge lamp
- Electromagnetism
- Dielectric barrier discharge