Plasma (physics)

File:Plasma microfields.webm

plasma fountain

Bliksem in Assen

Magnetic rope

Simple representation of a discharge tube - plasma

Plasma jacobs ladder

Plasma (physics) is one of the four fundamental states of matter, alongside solid, liquid, and gas. It is formed when a gas is heated to high temperatures or subjected to a strong electromagnetic field, causing the atoms to ionize. This means that the electrons are separated from their nuclei, creating a soup of charged particles: positively charged ions and negatively charged electrons. Plasma is distinct from other states of matter in that it contains free charged particles, making it highly electrically conductive and responsive to electromagnetic fields.

Characteristics

Plasma is often referred to as the "fourth state of matter" because its properties are significantly different from those of solids, liquids, and gases. It is the most abundant form of visible matter in the universe, making up more than 99% of the visible universe, including stars like the Sun, the interstellar medium, and the intergalactic medium. On Earth, plasma is naturally found in lightning, auroras, and fire.

The behavior of plasma is dominated by electromagnetic forces, which can lead to complex behaviors such as filamentation, self-organization, and the formation of structures like plasma double layers. Plasma temperature can vary widely, from relatively cool plasmas in neon signs and plasma globes to the extremely hot plasmas found in fusion reactors and the core of stars.

Types of Plasma

Plasmas can be classified based on their temperature and density. High-temperature plasmas, where the electrons and ions have reached thermal equilibrium, are called thermal plasmas. Non-thermal, or cold plasmas, have electrons at a much higher temperature than the ions. These distinctions are important in the study of plasma physics and its applications, including controlled nuclear fusion, plasma medicine, and plasma technology.

Astrophysical Plasma

The majority of the visible universe is in the plasma state. Examples include the Sun and other stars, the interstellar medium, and nebulae. Astrophysical plasmas are typically very hot and can be observed through telescopes using various wavelengths, from radio waves to X-rays.

Laboratory Plasma

Scientists create and study plasma in the laboratory to understand its properties and to develop applications such as nuclear fusion power and advanced manufacturing processes. Devices like tokamaks and stellarators are used to confine plasma in magnetic fields for fusion research.

Applications

Plasma has a wide range of applications. In industry, it is used for plasma cutting, plasma spraying for surface treatment, and in the manufacturing of semiconductor devices. In medicine, plasma technology is used for sterilization and in some treatments, such as wound healing. Plasma displays were a popular application in television screens, although they have been largely replaced by LED and OLED technologies.

Plasma Physics

Plasma physics is the field of physics that studies the properties, dynamics, and applications of plasma. It is a highly interdisciplinary field, overlapping with nuclear physics, astrophysics, and electrical engineering. Plasma physics research is crucial for the development of fusion energy, a potential source of clean, virtually unlimited power.

See Also

• Ionosphere
• Magnetohydrodynamics
• Plasma actuator
• Plasma window