{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"9da2b6d3ee4e56d6ee491c704d58c3d55127ba91cab27439ff0645104a78c491","created":"2026-10-03T07:18:08Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"cecebe4b5e828b60fd5a7a56cdd5478b8f13b052bff6fa3dae7c7e183771c62e","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"plasma.edge-pedestal-elms.heat-flux-width","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"Exhaust heat leaves a tokamak in a very thin layer along the boundary field lines and lands on a narrow stripe of the divertor plate. Its width decides whether the plate survives, and theory and data disagree on how wide it will be in ITER.","posed_since":"","precise":"A multi-machine regression gives an inter-ELM heat flux width $\\lambda_{q}$ inversely proportional to the outboard-midplane poloidal field, extrapolating to about $0.1\\,\\mathrm{cm}$ for ITER, while gyrokinetic XGC simulations predict about $0.5\\,\\mathrm{cm}$. Determine $\\lambda_{q}$ for the ITER $Q = 10$ baseline to within 30 percent and identify the mechanism (magnetic drifts versus edge turbulence) that sets it.","problem_ref":null,"references":"","settled_by":"Simulations validated at high poloidal field (e.g. on SPARC-class devices), then direct ITER measurement.","status_note":"The empirical extrapolation and XGC predictions (2017) differ by a factor of about 5.","title":"Scrape-off-layer heat flux width in ITER and reactors","topic_ref":"037681ebe2f068d361e19b0b90c7ad8b9281d3aee6de68370b6a285f803d9ac9"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"42868202b54b6a4ec4ef777ad8e672f5a788f0885614f8afe0605ff886543b8b","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"31ef330360a8a94ff115e6cb123e24bb3f9e64ca00e2b7770c11ac4f97d0658b","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"e40pkxUWl0ro5Z-GgKGBBd25fhkwp0wOGC1gEiLwSgV-hl-0tw21pP-qtqp932Hmto1X-aPmZjylvRe6UoQJAg"},"schema":"pubphys.envelope/1"},"record_hash":"42868202b54b6a4ec4ef777ad8e672f5a788f0885614f8afe0605ff886543b8b","leaf_index":1833}