Plasma Physics — 60 Terms Defined

Relativistic Plasma Plasma Physics keV or MeV (Thermal Energy) A high-energy density plasma where thermal electron energies approach or exceed rest mass energy (511 keV), requiring relativistic plasma dynamics. k_B T_e ≳ m_e c² ≈ 511 keV, γ_e ≫ 1

Reversed Field Pinch (RFP) Plasma Physics T (Toroidal Field B_T) A toroidal magnetic confinement device in which the toroidal magnetic field self-reverses direction near the outer edge of the plasma column. B_toroidal reverses direction near plasma edge (q < 1)

Saha Ionization Equation Plasma Physics m⁻³ (Ionization Balance Density) A thermodynamic relation expressing the ionization state of a plasma in thermal equilibrium as a function of temperature and electron density. (n_i+1 n_e) / n_i = (2 g_i+1 / g_i) (2 π m_e k_B T / h²)^(3/2) e^(-E_ion / (k_B T))

Solar Wind Plasma Physics km/s (Velocity) & cm⁻³ (Density) A continuous supersonic stream of fully ionized magnetoplasma (protons, electrons, alpha particles) expanding outward from the Sun's corona into interstellar space. v_sw ≈ 300–800 km/s, n_e ≈ 5 cm⁻³ at 1 AU

Stellarator Plasma Physics Dimensionless Magnetic Transform A magnetic confinement fusion device that produces a helical magnetic field using complex, 3D non-planar external electromagnetic coils without requiring net plasma current. Rotational Transform ι = 1 / q (Generated entirely by 3D external coils)

Thermal vs Non-Thermal Plasmas Plasma Physics Kelvin or eV The classification of plasmas based on thermodynamic equilibrium between electron temperature T_e and heavy ion/gas temperature T_i. Thermal: T_e ≈ T_i ≈ T_gas; Non-Thermal: T_e ≫ T_i ≈ T_gas

Tokamak Plasma Physics Dimensionless Safety Factor q A toroidal magnetic confinement fusion device that utilizes external magnetic coils and an internal driven plasma current to create a helical magnetic field. q = (r B_toroidal) / (R B_poloidal)

Two-Stream Instability Plasma Physics s⁻¹ (Growth Rate Im(ω)) A fundamental electrodynamic plasma instability that occurs when two counter-streaming particle beams or an electron beam injected into a stationary plasma excite growing electrostatic waves. 1 = (ω_pe1² / (ω - k v₁)²) + (ω_pe2² / (ω - k v₂)²)

Upper & Lower Hybrid Resonances Plasma Physics rad/s (Resonance Frequencies) Characteristic wave resonance frequencies in magnetized plasmas where wave group velocity vanishes and electromagnetic energy couples efficiently into plasma heating. Upper: ω_UH = √(ω_pe² + ω_ce²); Lower: 1 / ω_LH² = 1 / (ω_ci² + ω_pi²) + 1 / (ω_ce ω_ci)

Vlasov Equation Plasma Physics Collisionless Kinetic Operator The fundamental partial differential equation governing the evolution of the single-particle distribution function f(r, v, t) in a collisionless plasma. ∂f / ∂t + v · ∇_r f + (q / m) (E + v × B) · ∇_v f = 0

Whistler Waves Plasma Physics Audio Frequency Pitch Glissando (kHz) A right-hand circularly polarized electromagnetic wave mode propagating along magnetic field lines in a magnetized plasma below electron cyclotron frequency. v_phase = c √(ω ω_ce) / ω_pe (For ω ≪ ω_ce)

Z-Pinch Plasma Physics MA (Mega-amperes Current) A plasma confinement geometry where an axial electric current passed through a plasma column generates a self-pinching azimuthal magnetic field. Bennett Relation: I² = (8 π / μ₀) N k_B (T_e + T_i)