plazmafüüsikat

Plasma physics is the study of plasmas, ionized gases in which free electrons and ions interact collectively through electromagnetic fields. Plasma is considered the fourth state of matter, arising when sufficient energy ionizes a gas. Plasmas are abundant in the universe, from stars and interstellar matter to the solar wind, and they also appear in many laboratory and technological contexts.

Key properties include Debye shielding, which describes how electric fields are screened over a characteristic Debye length, and the plasma frequency, which sets the natural response time of electrons. Plasmas are typically quasi-neutral on macroscopic scales but can sustain local charge separations near boundaries. They often exhibit strong coupling to magnetic fields, supporting a rich set of waves and instabilities, and they can be magnetized, leading to magnetohydrodynamic (MHD) behavior.

The theoretical framework combines Maxwell’s equations with kinetic (Vlasov/Boltzmann) and fluid (MHD) models. Important phenomena include Langmuir waves, Alfvén waves, magnetic reconnection, and sheath formation at material boundaries. Diagnostic methods commonly use spectroscopy, Langmuir probes, and laser-based techniques to measure temperature, density, and flow.

Subfields span low-temperature plasmas used in industry (semiconductor processing, lighting, surface treatment, sterilization) and high-temperature plasmas relevant to fusion energy and astrophysics. Practical fusion research employs magnetically confined plasmas in devices such as tokamaks and stellarators. Space plasmas and astrophysical plasmas underpin understanding of the Sun, planets, and the interstellar medium.

This field is referred to as plazmafüüsikat in Estonian.