27:null 28:["$","title",null,{"children":"Plasma | Antoine Faché | Observable"}] 2d:[] 2b:{"id":"678a43c958ed346e","slug":null,"title":"Plasma","thumbnail":"4791b490c6821069ea9cf7c64882a3111c92536116cfc480b505ad640783662d","access_level":"public","create_time":"$D2026-04-21T04:12:07.918Z","update_time":"$D2026-04-21T04:12:07.918Z","view_time":null,"first_public_time":"$D2026-04-21T04:12:07.918Z","has_unpublished_edits":null,"fork":{"id":"1d2a2cf0c094d59d","slug":"plasma","title":"Plasma","owner":{"id":"dc625de0fe5f3eae","login":"vasturiano","name":"Vasco Asturiano"}},"stars":0,"starred":false,"owner":{"type":"team","id":"ab5c695e0d9f5ed0","login":"anthonyzornig","name":"Antoine Faché","avatar_url":"https://avatars-next.observableusercontent.com/73fe10f97d0449896f1255d6ce2abd09ac0d89a7c87afb645a54faeb67cc288a","tier":"starter_2024"},"version":90,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"a6dae7277d3d666a","login":"anthonyzornig","name":"Antoine Faché","avatar_url":"https://avatars-next.observableusercontent.com/73fe10f97d0449896f1255d6ce2abd09ac0d89a7c87afb645a54faeb67cc288a","tier":null}],"members":[{"type":"individual","id":"a6dae7277d3d666a","login":"anthonyzornig","name":"Antoine Faché","avatar_url":"https://avatars-next.observableusercontent.com/73fe10f97d0449896f1255d6ce2abd09ac0d89a7c87afb645a54faeb67cc288a","tier":null,"role":"editor"},{"type":"team","id":"ab5c695e0d9f5ed0","login":"anthonyzornig","name":"Antoine Faché","avatar_url":"https://avatars-next.observableusercontent.com/73fe10f97d0449896f1255d6ce2abd09ac0d89a7c87afb645a54faeb67cc288a","tier":"starter_2024","role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":0,"collection":null,"type":"notebook","body":{"title":"Plasma","cells":[{"id":0,"value":"# Plasma\n\nSimulation of attraction-of-opposites particles, similar to the interaction between protons and electrons.\n\nUses D3's force plugin [forceMagnetic](https://github.com/vasturiano/d3-force-magnetic) to simulate the asymmetrical attraction/repulsion of objects in an [inverse-square relationship](https://en.wikipedia.org/wiki/Inverse-square_law) with distance.\nFurther, particles are prevented from overlapping by applying a non-elastic collision force using [forceBounce](https://github.com/vasturiano/d3-force-bounce). \n\nUsing the slider controls you can add/remove particles to the system, and regulate the ratio of positive (+) vs negative (-) particles.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":42,"value":"viewof particleDensity = slider({\n min: 0, \n max: 3000, \n step: 10,\n value: 800,\n format: v => `${v} particles/kpx²`,\n title: 'Density'\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":45,"value":"viewof probPositive = slider({\n min: 0, \n max: 1, \n step: 0.01,\n value: 0.03,\n format: v => html`${Math.round((1 - v) * 100)}% Electrons(-) | ${Math.round(v * 100)}% Protons(+)`,\n title: 'Polarity'\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":26,"value":"domEl = html`

`;","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":75,"value":"pod = { \n const pod = d3ForcePod()(domEl)\n .nodeColor(({ pole }) => COLORS[pole > 0 ? 'positive' : 'negative']);\n\n // Add collision force\n pod.addForce(d3.forceBounce()\n\t\t.radius(d => d.r)\n\t\t.elasticity(0)\n\t);\n\n // Add attraction force\n\tpod.addForce(d3.forceMagnetic()\n .charge(node => node.r*node.r*node.pole*(node.pole>0 ? PROTON_ELECTRON_CHARGE_RATIO : 1))\n\t\t.strength(ACCELERATION_K)\n\t\t.polarity((q1,q2) => q1*q2 < 0) // Attraction of opposites\n\t);\n \n return pod;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":38,"value":"nodes = {\n const numParticles = Math.round(pod.width() * pod.height() * particleDensity / 1e6), // control in kpx^2\n\t\texistingParticles = pod.nodes();\n\n const nodes = numParticles === existingParticles.length\n // Keep as is\n ? existingParticles\n : (numParticles < existingParticles.length)\n // Trim\n ? existingParticles.slice(0, numParticles)\n // Append\n : [...existingParticles, ...[...new Array(numParticles - existingParticles.length)].map(() => ({\n \t\t\tx: Math.random() * pod.width(),\n \t\t\ty: Math.random() * pod.height(),\n \t\t\tr: PROTON_RADIUS,\n pole: 1\n\t\t })\n )];\n\n\tconst negThreshold = Math.floor(probPositive * numParticles);\n\tnodes.forEach((node, i) => {\n node.r = i < negThreshold ? PROTON_RADIUS : ELECTRON_RADIUS;\n\t\tnode.pole = i < negThreshold ? 1 : -1;\n });\n\n pod.nodes(nodes);\n\n return nodes;\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":17,"value":"**Container**","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":29,"value":"height = {\n const height = Math.min(MAX_HEIGHT, width / ASPECT_RATIO);\n \n pod.width(width).height(height);\n \n return height;\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":19,"value":"**Constants**","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":32,"value":"ASPECT_RATIO = 16 / 9;","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":35,"value":"MAX_HEIGHT = 600","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":50,"value":"COLORS = ({ positive: 'crimson', negative: 'darkslategrey'})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":58,"value":"PROTON_RADIUS = 9","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":60,"value":"ELECTRON_RADIUS = 2.5","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":64,"value":"PROTON_ELECTRON_CHARGE_RATIO = 10","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":67,"value":"ACCELERATION_K = 0.05","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":9,"value":"**Dependencies**","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":11,"value":"d3ForcePod = require('d3-force-pod@1.1.2')","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":14,"value":"d3 = require('d3-force-bounce', 'd3-force-magnetic')","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":5,"value":"import {slider} from \"@jashkenas/inputs\"","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W2d","stdlib":"1","titling":"auto"}} 2c:"$2b:body"