elektronjonplasma

Elektronjonplasma (electron–ion plasma) is a plasma in which free electrons coexist with positively charged ions. It is the most common form of plasma in the universe and is routinely produced in laboratories, including fusion devices, glow discharges, and plasma processing.

On macroscopic scales the plasma is quasi-neutral, with local charge imbalances screened by the Debye mechanism. Its dynamics are governed by electromagnetic fields described by Maxwell's equations, coupled to the motion of the charged species. Key frequencies include the electron plasma frequency ωp and the ion plasma frequency ωpi; electrons respond on much shorter timescales than ions. The two-fluid nature of the system means electrons and ions can have different temperatures and flows, leading to a range of collective phenomena.

The system is often described by a two-fluid model, treating electrons and ions as interpenetrating fluids with different masses, or by magnetohydrodynamics when magnetic fields are important. If a magnetic field is present, waves such as Alfvén waves, ion-acoustic waves, and magnetosonic modes can propagate, reflecting the coupled dynamics of charge, mass, and temperature.

Compositions range from fully ionized plasmas in stars and fusion devices to partially ionized plasmas in some laboratory and industrial contexts. Multiple ion species can be present, leading to a spectrum of ion dynamics and characteristic frequencies.

Applications and occurrences include astrophysical plasmas (solar wind, interstellar and intergalactic media), laboratory fusion devices (tokamaks and stellarators), plasma processing and microfabrication, and high-energy density physics involving laser–plasma interactions.

Diagnostics commonly used to study electron–ion plasmas include Langmuir probes, Thomson scattering, interferometry, and spectroscopy to measure densities, temperatures, and flow velocities.