{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"cfa8aab097b0a9155b5883695cf9bfb7f801f225207a3e070ceb6bd5950f44d1","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["c062acf8f46ff5531261ef4e58c7d1b7c756b77f6472a3e066b06c09f02d0ee1","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"3e0af3cfbec6cea82473c81c8f31d5fda0a391f738b91f9becffe06c8c860777","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"plasma.tokamak-confinement.lh-transition-mechanism","kind":"phenomenon","literature_status":"open","n":"2","parents":[],"plain":"When enough heating power is applied, a tokamak's edge turbulence switches off within a fraction of a millisecond and a steep insulating edge forms. More than forty years after its discovery, what causes the switch is not agreed.","posed_since":"1982","precise":"In diverted tokamaks, identify the mechanism that suppresses edge turbulence at the L-H transition within about $10^{-4}$ s: turbulence-driven zonal flows, the ion-diamagnetic radial electric field well, X-point ion orbit loss, or their combination. An answer is a flux-driven first-principles model (gyrokinetic or two-fluid, realistic diverted geometry) that reproduces the measured threshold power and its dependences on density, toroidal field direction, isotope and divertor geometry.","problem_ref":"c062acf8f46ff5531261ef4e58c7d1b7c756b77f6472a3e066b06c09f02d0ee1","references":"","settled_by":"A first-principles simulation that predicts the measured transition dynamics and threshold scalings on at least two devices without tuning.","status_note":"Flux-driven 3D two-fluid simulations reported in 2026 reproduce threshold, density-minimum and field-direction trends (arXiv:2605.00624), not yet validated across devices.","title":"Physical trigger of the L-H transition","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"4923308da7a60bf34f45291ba9f54d3fcc6c7af56d46862f31a0866ad027df6b","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"843e04973ba6b49998fcb875e1440e2c975acbc1744ca3d788315de2e9352f71","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"8RhE6GcdS2r-WKtOXRzDMjoAaK_b7b9Xb40jLVwN9XmYqEbT1QKqPDteJsb1KiYPr4tBl8gLgw3jgq6w7cieDQ"},"schema":"pubphys.envelope/1"},"record_hash":"4923308da7a60bf34f45291ba9f54d3fcc6c7af56d46862f31a0866ad027df6b","leaf_index":3612}