{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"5526f7fc23783aabe8bc758f014a29b997228ce797a2a65b36140c3bbec08c48","created":"2026-10-03T07:18:08Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"8c34372708426e8d63a09c64c68571f86edd620103bfbfc4e30fd952ca00dd22","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":"1","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 1e-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":null,"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":"06a56c8a16b24bd8d093b16cb10c927fc7bcbeff7471e51e9543e334992b233a"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"c062acf8f46ff5531261ef4e58c7d1b7c756b77f6472a3e066b06c09f02d0ee1","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"bbe2b00f50ca867e31a6089bd80515efe704c43b45f9c48bbb9c7a667f4f3b1b","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"-UmWbHoiL-9kao3hLPrPpwwT1Xv_y1mqXfekkGBxQYFnbz6Io2UaNpXYHw1FGIAkyVIORHMUsTeryCodsJwOAQ"},"schema":"pubphys.envelope/1"},"record_hash":"c062acf8f46ff5531261ef4e58c7d1b7c756b77f6472a3e066b06c09f02d0ee1","leaf_index":1876}