# Plasma (physics)
## Microsim
### Live player
<div class="microsim-player">
<iframe src="https://editor.p5js.org/sciencenibber/full/Tb2hfHDgn" width="100%" height="620" frameborder="0" sandbox="allow-scripts allow-same-origin"></iframe>
</div>
<div class="microsim-fallback">
<img src="Microsims/thumbs/Plasma_(physics).png" alt="Plasma_(physics) microsim poster" style="width:100%;border:1px solid #4445;border-radius:6px;">
<p><em>Live microsim (desktop) · <a href="https://editor.p5js.org/sciencenibber/sketches/Tb2hfHDgn">open sketch in the p5.js editor</a></em></p>
</div>
**Editor URL:** https://editor.p5js.org/sciencenibber/sketches/Tb2hfHDgn
**Description (100 words):**
A bounded slab of helium plasma sits inside a uniform magnetic field pointing into the page. Small blue dots are electrons; larger orange dots are singly ionized He+ atoms. Three sliders let the reader change the [[Electron|electron]] temperature in eV, the electron number [[Density|density]] in log10 of m^-3, and the field strength in tesla. As the dials move, the gyroradii and thermal speeds adjust visibly while seven derived numbers in the upper right (plasma frequency, Debye length, plasma parameter Lambda, thermal speeds, and Larmor radii) update in real time, and a dashed yellow ring shows the scaled Debye length.
```js
// =====================================================================
// Plasma_(physics).js -- Wikitube microsim
// Article: Plasma (physics) en.wikitube.io/wiki/Plasma_(physics)
// Room: Helium Pattern: E (particles / phase mixing)
// ---------------------------------------------------------------------
// Idea: A bounded slab of weakly coupled helium plasma sits in a
// uniform magnetic field B pointing into the page. The slab carries
// electrons (charge -e, mass m_e) and singly ionised He+ ions
// (charge +e, mass ~7295 * m_e). Each species is in thermal
// equilibrium at a temperature T_e (the same number is used for the
// ions here for visual clarity; in real laboratory plasmas T_e and
// T_i can differ by orders of magnitude). The reader drags three
// sliders (electron temperature in eV, electron number density in
// log10 of m^-3, magnetic field in tesla) and watches the gyration
// radii and thermal speeds change in real time, while the HUD on the
// upper right reports the three quantities that define a plasma:
// the plasma frequency omega_p, the Debye length lambda_D, and the
// plasma parameter Lambda = n * (4/3) pi lambda_D^3.
//
// Physics
// -------
// Lorentz force on each charge q is F = q (E + v x B). With E = 0
// and B = B_hat_z (into page) a charge of mass m moves on a circle
// of radius (Larmor / gyroradius)
//
// r_L = m v_perp / (|q| B)
//
// at the cyclotron frequency
//
// omega_c = |q| B / m
//
// Electrons gyrate ~7295x faster and ~7295x tighter than He+ ions at
// the same speed, which the eye sees as fine blue circles inside
// lazy orange loops.
//
// The plasma frequency is the electron-fluid restoring oscillation
//
// omega_p = sqrt(n_e e^2 / (epsilon_0 m_e))
//
// and electromagnetic waves with omega < omega_p cannot propagate
// through the plasma -- this is why the ionosphere reflects AM radio.
//
// The Debye length is the screening scale
//
// lambda_D = sqrt(epsilon_0 k_B T_e / (n_e e^2))
//
// Inside one Debye sphere a test charge looks bare; beyond it the
// cloud of opposite charges has neutralised it. A plasma is well
// defined only when many particles sit inside one Debye sphere:
//
// Lambda = n_e * (4/3) pi lambda_D^3 >> 1
//
// Helium's first ionisation energy is 24.587 eV (the highest of any
// neutral element), so striking a helium plasma is hard but the
// result is hot and chemically clean -- this is the regime relevant
// for inductively coupled plasma spectrometry and for plasma torches
// with helium as the shielding gas.
//
// Visual layout (720 x 520 canvas)
// --------------------------------
// * top-left: HUD title + en.wikitube.io/wiki/Plasma_(physics)
// * top-right: live readouts (omega_p, lambda_D, Lambda, r_Le,
// r_Li, v_th_e, v_th_i)
// * center: simulation box -- electrons drawn as small blue
// dots with short trails, He+ ions drawn as larger
// orange dots with longer trails. Background marked
// with faint "x x x" symbols to show B is into page.
// A grey dashed circle near the centre traces the
// Debye length (in pixels, after scaling) so the
// reader can see screening shrink with density.
// * bottom row: three sliders -- T_e (eV), log10 n_e (m^-3),
// B (T) -- plus a reset button.
// * bottom-right: ASCII equations for omega_p and lambda_D.
//
// Conventions (Wikitube Betterfire Standard v0)
// ---------------------------------------------
// * single ARTICLE constant, single quotes
// * p5.disableFriendlyErrors = true
// * non-ASCII (Greek, arrows) lives in COMMENTS ONLY; every
// text() string literal is plain ASCII
// * Energy-room palette (P5_JS_EDITOR section 4)
// * controls have explicit .position(x,y).size(w)
// * HUD drawn by drawHUD() called once per draw()
// =====================================================================
const ARTICLE = 'Plasma_(physics)';
const TITLE = 'Plasma (physics)';
p5.disableFriendlyErrors = true;
// ----- Energy-room palette (P5_JS_EDITOR section 4) ------------------
const BG = 18;
const FG = 240;
const DIM = [240, 240, 240, 140];
const HOT = [220, 110, 60]; // He+ ions (warm orange)
const COLD = [60, 130, 220]; // electrons (cool blue)
const STRUCT = [120, 130, 150]; // box outline, axes
const TRAJ = [240, 220, 80]; // Debye-sphere ring
const SCRATCH = [120, 120, 120, 80]; // "x" marks for B into page
const ACCENT = [200, 100, 220]; // accent text (sparingly)
// ----- Physical constants --------------------------------------------
const E_CHARGE = 1.602176634e-19; // C (exact, 2019 SI)
const M_ELEC = 9.1093837e-31; // kg
const M_HE_ION = 6.6446573e-27; // kg (He-4 nucleus, ~7295 m_e)
const KB = 1.380649e-23; // J / K (exact)
const EPS0 = 8.8541878128e-12; // F / m
const EV_TO_J = 1.602176634e-19; // J per eV
const PI = Math.PI;
// ----- Display constants ---------------------------------------------
const CANVAS_W = 720;
const CANVAS_H = 520;
// Plasma box on canvas (the "physical" simulation window).
const BOX_X = 50;
const BOX_Y = 60;
const BOX_W = 540;
const BOX_H = 320;
// We do NOT integrate at real (m, kg, s) -- the gyroradii of real
// electrons at lab fields are micrometres, far below one pixel. The
// sketch is a *kinematic toy*: each species draws on a thermal speed
// distribution derived from real physics, then is drawn at a scale
// that keeps the orbits visible. The HUD reports the real numbers.
// Visual scale: pixels per "simulated metre" of in-box motion.
// We pick PIX_PER_M so that an electron at T_e = 10 eV in B = 0.1 T
// makes a ~25 px gyroradius -- comfortable to see.
let PIX_PER_M = 0; // set in setup()
// ----- Slider handles ------------------------------------------------
let teSlider, logNeSlider, bSlider, resetBtn;
// ----- Particle stores -----------------------------------------------
// Each particle: {x, y, vx, vy, history:[{x,y}]}.
const electrons = [];
const ions = [];
const N_E = 90; // visible electron count
const N_I = 45; // visible ion count
const TRAIL_E = 14; // short trail for fast electrons
const TRAIL_I = 26; // longer trail for slow ions
// ----- Derived plasma quantities (recomputed each frame) -------------
let omega_p_real = 0; // rad / s
let lambda_D_real = 0; // m
let Lambda_param = 0; // dimensionless
let v_th_e_real = 0; // m / s
let v_th_i_real = 0; // m / s
let r_Le_real = 0; // m
let r_Li_real = 0; // m
// ----- Setup ---------------------------------------------------------
function setup() {
createCanvas(CANVAS_W, CANVAS_H);
pixelDensity(2);
textFont('system-ui');
// Choose PIX_PER_M so that 25 px == r_L of a 10 eV electron in 0.1 T.
// r_L = m v / (e B); v = sqrt(2 k_B T / m). With T = 10 eV / k_B,
// v ~ 1.876e6 m/s, r_L ~ 1.07e-4 m. So 25 px / 1.07e-4 m ~ 2.34e5.
PIX_PER_M = 25 / 1.07e-4;
// T_e (electron temperature in eV): 0.5 -> 100, default 10
teSlider = createSlider(0.5, 100, 10, 0.5).position(20, CANVAS_H + 10).size(170);
// log10(n_e) (m^-3): 12 -> 22, default 18 (lab plasma)
logNeSlider = createSlider(12, 22, 18, 0.1).position(220, CANVAS_H + 10).size(170);
// B field (Tesla): 0 -> 1.0, default 0.1
bSlider = createSlider(0, 1.0, 0.1, 0.01).position(420, CANVAS_H + 10).size(170);
resetBtn = createButton('reset').position(620, CANVAS_H + 10).size(70, 22);
resetBtn.mousePressed(() => { seedParticles(); });
seedParticles();
}
// ----- Particle seeding ---------------------------------------------
// Maxwell-Boltzmann thermal velocity by Box-Muller from a 1D Gaussian
// with std dev sqrt(k_B T / m). We pick velocities in physical units
// and convert to screen via PIX_PER_M when drawing.
function gauss() {
// Box-Muller transform.
let u1 = random();
let u2 = random();
if (u1 < 1e-9) u1 = 1e-9;
return Math.sqrt(-2 * Math.log(u1)) * Math.cos(2 * PI * u2);
}
function seedParticles() {
electrons.length = 0;
ions.length = 0;
const T_e_eV = teSlider ? teSlider.value() : 10;
const T_K = (T_e_eV * EV_TO_J) / KB;
const sigma_e = Math.sqrt(KB * T_K / M_ELEC);
const sigma_i = Math.sqrt(KB * T_K / M_HE_ION);
for (let i = 0; i < N_E; i++) {
electrons.push({
x: random(BOX_X + 20, BOX_X + BOX_W - 20),
y: random(BOX_Y + 20, BOX_Y + BOX_H - 20),
vx: gauss() * sigma_e,
vy: gauss() * sigma_e,
history: []
});
}
for (let i = 0; i < N_I; i++) {
ions.push({
x: random(BOX_X + 20, BOX_X + BOX_W - 20),
y: random(BOX_Y + 20, BOX_Y + BOX_H - 20),
vx: gauss() * sigma_i,
vy: gauss() * sigma_i,
history: []
});
}
}
// ----- One symplectic-Euler step for one charged particle -----------
// q is signed (+1 for ion, -1 for electron). The Lorentz acceleration
// from a uniform B into the page on a 2D particle is a rotation:
// a = (q / m) * (v x B), with B = B_z hat_z (out of page in math
// convention; we flip sign so positive B in the slider means INTO
// page in screen coords). For v = (vx, vy, 0), B = (0, 0, B):
// v x B = (vy * B, -vx * B, 0).
// E = 0 here (no biased electrodes; this is a static slab).
function stepParticle(p, q_sign, mass, B, dt) {
const qOverM = q_sign * E_CHARGE / mass;
const ax = qOverM * (p.vy * B);
const ay = qOverM * (-p.vx * B);
p.vx += ax * dt;
p.vy += ay * dt;
// Update position in "physical" metres internally? No -- we keep
// (vx, vy) in m/s and integrate the position in METRES, then map
// to pixels on draw. Simpler: integrate in PIXELS by scaling v.
p.x += p.vx * PIX_PER_M * dt;
p.y += p.vy * PIX_PER_M * dt;
// Periodic boundary in the simulation box -- charges that exit one
// side re-enter the other. This is the standard plasma-simulation
// boundary for visualising a bulk medium.
if (p.x < BOX_X) p.x += BOX_W;
if (p.x > BOX_X + BOX_W) p.x -= BOX_W;
if (p.y < BOX_Y) p.y += BOX_H;
if (p.y > BOX_Y + BOX_H) p.y -= BOX_H;
// Record trail.
const trailMax = (mass === M_ELEC) ? TRAIL_E : TRAIL_I;
p.history.push({ x: p.x, y: p.y });
if (p.history.length > trailMax) p.history.shift();
}
// ----- Recompute the four derived plasma numbers --------------------
function updatePlasmaNumbers() {
const T_e_eV = teSlider.value();
const T_K = (T_e_eV * EV_TO_J) / KB;
const n_e = Math.pow(10, logNeSlider.value());
const B = bSlider.value();
v_th_e_real = Math.sqrt(KB * T_K / M_ELEC);
v_th_i_real = Math.sqrt(KB * T_K / M_HE_ION);
omega_p_real = Math.sqrt(n_e * E_CHARGE * E_CHARGE / (EPS0 * M_ELEC));
lambda_D_real = Math.sqrt(EPS0 * KB * T_K / (n_e * E_CHARGE * E_CHARGE));
Lambda_param = n_e * (4 / 3) * PI * Math.pow(lambda_D_real, 3);
if (B > 1e-6) {
r_Le_real = M_ELEC * v_th_e_real / (E_CHARGE * B);
r_Li_real = M_HE_ION * v_th_i_real / (E_CHARGE * B);
} else {
r_Le_real = Infinity;
r_Li_real = Infinity;
}
}
// ----- Main draw -----------------------------------------------------
function draw() {
background(BG);
updatePlasmaNumbers();
// Time step. We use a fixed visual dt; this is a kinematic toy, so
// we do NOT use deltaTime / 1000 -- a slow tab should not make the
// gyroradius drift larger.
const dt = 4e-9; // 4 ns of "simulated" time per draw call
const B = bSlider.value();
for (const e of electrons) stepParticle(e, -1, M_ELEC, B, dt);
for (const i of ions) stepParticle(i, +1, M_HE_ION, B, dt);
drawBox();
drawDebyeRing();
drawParticles();
drawHUD();
drawReadouts();
drawEquations();
drawSliderLabels();
}
// ----- The plasma box and B-into-page markers -----------------------
function drawBox() {
noFill();
stroke(STRUCT);
strokeWeight(1);
rect(BOX_X, BOX_Y, BOX_W, BOX_H);
// "x x x" lattice marking B into page.
noStroke();
fill(...SCRATCH);
textSize(12);
textAlign(CENTER, CENTER);
for (let gx = BOX_X + 30; gx < BOX_X + BOX_W; gx += 60) {
for (let gy = BOX_Y + 30; gy < BOX_Y + BOX_H; gy += 60) {
text('x', gx, gy);
}
}
textAlign(LEFT, BASELINE);
}
// ----- Debye-length ring drawn at the centre of the box --------------
function drawDebyeRing() {
const ring_r = Math.min(140, Math.max(2, lambda_D_real * PIX_PER_M * 1e6));
noFill();
stroke(...TRAJ);
strokeWeight(1);
drawingContext.setLineDash([5, 5]);
ellipse(BOX_X + BOX_W / 2, BOX_Y + BOX_H / 2, ring_r * 2, ring_r * 2);
drawingContext.setLineDash([]);
noStroke();
fill(...TRAJ);
textSize(11);
text('Debye ring (visual)', BOX_X + BOX_W / 2 + ring_r + 6,
BOX_Y + BOX_H / 2);
}
// ----- Particles + trails --------------------------------------------
function drawParticles() {
// He+ ions (orange) drawn first so electrons render on top.
for (const p of ions) {
noFill();
stroke(HOT[0], HOT[1], HOT[2], 130);
strokeWeight(1);
beginShape();
for (const h of p.history) vertex(h.x, h.y);
endShape();
noStroke();
fill(HOT);
ellipse(p.x, p.y, 6, 6);
}
// Electrons (blue) on top.
for (const p of electrons) {
noFill();
stroke(COLD[0], COLD[1], COLD[2], 170);
strokeWeight(1);
beginShape();
for (const h of p.history) vertex(h.x, h.y);
endShape();
noStroke();
fill(COLD);
ellipse(p.x, p.y, 3.5, 3.5);
}
}
// ----- HUD: title and wikitube URL (top-left) ------------------------
function drawHUD() {
noStroke();
fill(FG);
textSize(22);
textStyle(BOLD);
text(TITLE, 14, 30);
textSize(12);
textStyle(NORMAL);
fill(...DIM);
text('Wikitube microsim . en.wikitube.io/wiki/' + ARTICLE, 14, 48);
}
// ----- Live readouts (top-right) -------------------------------------
function drawReadouts() {
const x = CANVAS_W - 14;
let y = 26;
noStroke();
fill(FG);
textSize(11);
textAlign(RIGHT, BASELINE);
text('omega_p = ' + omega_p_real.toExponential(3) + ' rad/s', x, y); y += 14;
text('lambda_D = ' + lambda_D_real.toExponential(3) + ' m', x, y); y += 14;
text('Lambda = ' + Lambda_param.toExponential(3), x, y); y += 14;
text('v_th_e = ' + v_th_e_real.toExponential(3) + ' m/s', x, y); y += 14;
text('v_th_i = ' + v_th_i_real.toExponential(3) + ' m/s', x, y); y += 14;
if (isFinite(r_Le_real)) {
text('r_L,e = ' + r_Le_real.toExponential(3) + ' m', x, y); y += 14;
text('r_L,i = ' + r_Li_real.toExponential(3) + ' m', x, y); y += 14;
} else {
text('r_L,e = inf (B = 0)', x, y); y += 14;
text('r_L,i = inf (B = 0)', x, y); y += 14;
}
// Plasma regime annotation.
fill(Lambda_param > 1 ? COLD : HOT);
text(Lambda_param > 1 ? 'Lambda >> 1: collective (plasma)'
: 'Lambda < 1: not a plasma',
x, y);
textAlign(LEFT, BASELINE);
}
// ----- Canonical equations (bottom-right) ----------------------------
function drawEquations() {
noStroke();
fill(...DIM);
textSize(11);
textAlign(RIGHT, BASELINE);
text('omega_p = sqrt(n_e e^2 / (eps_0 m_e))', CANVAS_W - 14, CANVAS_H - 28);
text('lambda_D = sqrt(eps_0 k_B T_e / (n_e e^2))', CANVAS_W - 14, CANVAS_H - 14);
textAlign(LEFT, BASELINE);
}
// ----- Slider labels (just above each slider) ------------------------
function drawSliderLabels() {
noStroke();
fill(FG);
textSize(11);
text('T_e = ' + teSlider.value().toFixed(1) + ' eV',
20, CANVAS_H + 8);
text('log10(n_e / m^-3) = ' + logNeSlider.value().toFixed(2),
220, CANVAS_H + 8);
text('B = ' + bSlider.value().toFixed(2) + ' T',
420, CANVAS_H + 8);
}
```
## Links (Wikipedia order)
<!-- injected from _registry/childlinks/Plasma_(physics).json (2026-07-30T02:09:12Z) -->
`Academic_Press` · `Accretion_disk` · `Acoustics` · `Adhesion` · `Adolf_Eugen_Fick` · [[Aerospace_engineering]] · [[Aluminium]] · `American_Journal_of_Physics` · `Analytical_mechanics` · `Anode` · `Antiferromagnetism` · `Antimatter` · `Applied_physics` · `Archimedes'_principle` · `Astrophysical_plasma` · `Astrophysics` · `Atmosphere` · `Atmosphere_of_Earth` · `Atmospheric_entry` · `Atmospheric_physics` · `Atomic,_molecular,_and_optical_physics` · `Atomic_physics` · `Augustin-Louis_Cauchy` · `Basic_research` · `Bending` · `Bernoulli's_principle` · `Binary_star` · `Binodal` · `Biophysics` · `Birkeland_current` · `Blaise_Pascal` · `Blood_plasma` · `Body_fluid` · `Boiling` · [[Boiling_point]] · `Bose–Einstein_condensate` · `Boyle's_law` · `Branches_of_physics` · `Buoyancy` · `CRC_Press` · `Capillary_action` · `Cathode` · `Celestial_mechanics` · `Charge_density` · `Charged_particle` · `Charles's_law` · `Chemical_ionization` · `Chemical_physics` · `Chemical_synthesis` · `Chromatography` · `Classical_electromagnetism` · `Classical_mechanics` · `Classical_physics` · `Claude-Louis_Navier` · `Clausius–Duhem_inequality` · `Clifford_Truesdell` · `Cohesion_(chemistry)` · `Collision` · `Colloid` · `Color-glass_condensate` · `Compatibility_(mechanics)` · [[Complex_system]] · `Compressed_fluid` · `Computational_physics` · `Computer_simulation` · `Condensation` · `Condensed_matter_physics` · `Conservation_of_energy` · `Conservation_of_mass` · `Contact_mechanics` · `Continuum_mechanics` · `Cooling_curve` · `Corona_discharge` · `Critical_line_(thermodynamics)` · `Critical_point_(thermodynamics)` · `Crystal` · `Crystallization` · `Crystallography` · `Daniel_Bernoulli` · `Dark_matter` · `David_A._Frank-Kamenetskii` · `Debye_length` · `Deformation_(physics)` · `Degenerate_matter` · `Deposition_(phase_transition)` · `Dielectric_strength` · `Direct_current` · `Distribution_function_(physics)` · `Drag_(physics)` · [[Earth]] · `Efficiency` · `Elastic_collision` · `Elasticity_(physics)` · `Electric_arc` · `Electric_charge` · [[Electric_current]] · `Electric_field` · `Electric_spark` · `Electrical_breakdown` · `Electrical_conductor` · `Electrical_energy` · `Electrical_resistivity_and_conductivity` · `Electricity` · `Electroluminescence` · `Electromagnetic_field` · `Electromagnetism` · [[Electron]] · `Electronvolt` · `Electrorheological_fluid` · `Elementary_charge` · [[Engineering_physics]] · `Enthalpy_of_fusion` · `Enthalpy_of_sublimation` · `Enthalpy_of_vaporization` · `Equation_of_state` · `Etching` · `Evaporation` · `Exotic_matter` · `Experimental_physics` · `Fermi_gas` · `Fermionic_condensate` · `Ferrimagnetism` · `Ferrofluid` · `Ferromagnetism` · `Fick's_laws_of_diffusion` · `Finite_strain_theory` · `Fire` · `Flash_evaporation` · `Fluid` · [[Fluid_dynamics]] · `Fluid_mechanics` · `Fluorescent_lamp` · [[Fractal]] · [[Fracture_mechanics]] · `Freezing` · `Frictional_contact_mechanics` · `Galaxy` · `Gas` · `Gay-Lussac's_law` · `General_relativity` · `Geometrical_optics` · `Geophysics` · `Glow_discharge` · `Graham's_law` · `Gravity` · `Gyrokinetics` · `Hagen–Poiseuille_equation` · `Hall-effect_thruster` · `Hall_effect` · `Hannes_Alfvén` · `Heat` · `Heat_shield` · `History_of_electromagnetic_theory` · `History_of_physics` · `Hooke's_law` · `HowStuffWorks` · `Humphry_Davy` · `Hydrostatics` · `Inductively_coupled_plasma` · `Infinitesimal_strain_theory` · `Instability` · `Insulator_(electricity)` · `International_Space_Station` · `Interplanetary_medium` · `Interstellar_medium` · `Intracluster_medium` · [[Ion]] · `Ion_thruster` · `Ionization` · [[Ionization_energy]] · `Ionosphere` · `Irving_Langmuir` · [[Isaac_Newton]] · `Jacques_Charles` · `Joseph_Louis_Gay-Lussac` · `Kelvin` · `Kinetic_energy` · `Lambda_point` · `Laser` · `Latent_heat` · `Latent_internal_energy` · `Leidenfrost_effect` · `Leonhard_Euler` · `Lightning` · `Linear_elasticity` · `Liquid` · `Liquid_crystal` · [[List_of_plasma_physics_software]] · `List_of_states_of_matter` · `Lorentz_force` · `MIT_Plasma_Science_and_Fusion_Center` · `Macroscopic_quantum_phenomena` · `Magnetic_Reynolds_number` · `Magnetic_field` · `Magnetohydrodynamic_generator` · `Magnetohydrodynamics` · `Magnetorheological_fluid` · `Magnetosphere` · `Material_failure_theory` · [[Materials_science]] · `Mathematical_physics` · `Maxwell's_equations` · `Maxwell–Boltzmann_distribution` · `Medical_physics` · `Melting` · `Melting_point` · `Messier_87` · [[Metallurgy]] · `Michael_Faraday` · `Mixing_(process_engineering)` · `Modern_physics` · `Molding_(process)` · `Molecular_physics` · `Moving_parts` · `Mpemba_effect` · `NASA` · `Nanomaterials` · `Nature_(journal)` · `Navier–Stokes_equations` · `Nebula` · `Neon_sign` · `Neutron_star` · [[Newton's_laws_of_motion]] · `Newtonian_fluid` · `Nobel_Prize_in_Physics` · `Non-Newtonian_fluid` · `Non-equilibrium_thermodynamics` · [[Nuclear_fusion]] · `Nuclear_physics` · `Observable_universe` · `Optics` · `Outer_space` · `Outline_of_astrophysics` · `Ozone` · `Particle` · 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## From the Real GENERATIVE library
*Plasma (physics) — placed from the Real G.E.N.E.R.A.T.I.V.E. course library (Telecommunications room). Source: Wikimedia Commons (via Wikipedia article media). [Details & license](https://commons.wikimedia.org/wiki/File:Lightning3.jpg).*
*Animated: Plasma (physics) — placed from the Real G.E.N.E.R.A.T.I.V.E. course library (Telecommunications room). Source: Wikimedia Commons (via Wikipedia article media). [Details & license](https://commons.wikimedia.org/wiki/File:Plasma_fountain.gif).*
> Plasma (from Ancient Greek πλάσμα (plásma) 'moldable substance'[1]) is one of four fundamental states of matter (the other three being solid, liquid, and gas) characterized by the presence of a significant portion of charged particles in any combination of ions or electrons. It is the most abundant form of ordinary matter in the universe, mostly in stars (in ([Wikipedia](https://en.wikipedia.org/wiki/Plasma_%28physics%29))
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## Media (PD/CC)
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!Gif Library/Plasma (physics)/Plasma fountain.gif
*Plasma_fountain.gif · Public domain*
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**Semiotic universals** (the notations and alphabet letters this article speaks — each opens its canonical card): kanji radicals · temperature heat · energy · exponential · probability. Index: the glyph gallery · SEMIOTICS PORTAL.
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> **Room:** [[Helium]] · **Status:** ✅ shipped
## Overview
Plasma is the fourth state of matter, an ionized gas in which a significant fraction of atoms have been stripped of one or more electrons, leaving a quasi-neutral mixture of positive ions and free electrons that exhibits collective electromagnetic behavior absent in ordinary gases. The transition from gas to plasma occurs when thermal [[Energy|energy]] or external fields supply enough energy to overcome the ionization potential of atoms — for helium the first [[Ionization_energy|ionization energy]] is 24.587 eV, the highest of any neutral element, making helium plasmas comparatively difficult to strike but exceptionally hot and clean once formed. The defining length scale is the Debye length, lambda_D = sqrt(epsilon_0 k_B T_e / n_e e^2), over which free charges screen external fields; a plasma must contain many particles within a Debye sphere (plasma parameter Lambda >> 1) and oscillates at the plasma frequency omega_p = sqrt(n_e e^2 / epsilon_0 m_e), which fixes the cutoff for electromagnetic propagation. First identified by William Crookes in 1879 and named by Irving Langmuir in 1928, plasma comprises more than 99 percent of the visible universe — stellar interiors, the solar wind, interstellar gas, and the ionosphere — and underpins applications ranging from neon and fluorescent lighting and arc welding to semiconductor etching, magnetic-confinement fusion (where deuterium-tritium and helium-3 plasmas are heated above 100 million kelvin), inertial confinement, mass spectrometry, plasma thrusters for spacecraft, and the helium-shielded plasma torches used in industrial cutting and inductively coupled plasma spectrochemical analysis.
## See also
- Room hub: [[Helium]]
- p5.js Editor conventions: P5 JS EDITOR
- Wiki root: MAIN
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*Scaffolded by `generative-microsim` from row 180 of the Helium sheet on 2026-05-15T01:24:10Z.*
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*Built to the [[WT!P5_js_Microsim_Master_Class|p5.js Master Class]].*
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*Linked from the [[WT!Thury_Hydrodynamics_Compendium|Thury Hydrodynamics Compendium]], section 27, Magnetohydrodynamics.*
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**Microsim — three.js (Wikitube framework):** *Plasma (physics)*
<div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/thury/Plasma_(physics).html" data-title="Plasma (physics)"></div>
*Built from `MICROSIM_GUIDE/specs/variants/Plasma_(physics).json`; part of the [[WT!Thury_Hydrodynamics_Compendium|Thury Hydrodynamics Compendium]] set.*
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## Wikipedia : Wikitube
**Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Plasma_%28physics%29) : [Wikitube](https://en.wikitube.io/wiki/Plasma_%28physics%29)
## Previous hub tags
Tree parents: [[Helium]] · [[Hydrogen]] · [[Self-organization]].
Legacy hubs: none.
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*Sources: 1 legacy note. Minted wave 1, 2026-07-30 (v1.6 order).*