Plasmafysiikan

Plasmafysiikan, the study of plasmas, is the branch of physics that investigates ionized gases in which charged particles (electrons and ions) exhibit collective behavior governed by electromagnetic forces as well as collisions. Plasmas are the most common state of ordinary matter in the visible universe, found in stars, interstellar space, lightning, and many laboratory and technological devices.

Key concepts in the field include Debye shielding, plasma frequency, collective oscillations, collisionless behavior, and magnetohydrodynamics (MHD), which treats plasma as a conducting fluid influenced by magnetic fields. Plasmas are classified by temperature, density, and degree of ionization, ranging from cold, partially ionized laboratory plasmas to hot, fully ionized astrophysical plasmas.

Methodologies combine theory, numerical simulation, and experiment. Theoretical approaches span kinetic theory and fluid models; numerical techniques include particle-in-cell and hybrid codes; experimental tools include probes, spectroscopy, interferometry, and magnetic diagnostics. Plasmafysiikan addresses phenomena such as waves, instabilities, magnetic reconnection, and turbulence.

Applications are wide-ranging: controlled nuclear fusion research, spacecraft propulsion, semiconductor processing, lighting and displays, and space-weather forecasting. Historically, the discipline developed in the early 20th century with contributions from scientists studying gas discharges and astrophysical plasmas and has since become interdisciplinary, connecting atomic physics, electromagnetism, fluid dynamics, and computational science.