{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"2bbca8677f170edfb03db009287578c623dc60d4dad61e095e46c2814f5b97e1","created":"2026-10-03T07:18:08Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"38a2c81a3c8b708e527414eb2b72b0945e19bb2c4d26b23ff2440784e5ebf6d7","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"plasma.edge-pedestal-elms.pedestal-height-prediction","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"The pressure reached at the top of the edge layer largely decides how much fusion power a tokamak makes. Models that predict it work in many present machines but fail in some, such as those with metal walls and heavy gas fueling.","posed_since":"","precise":"Pedestal models of the EPED type combine the ideal peeling-ballooning stability limit with a kinetic-ballooning-mode constraint on pedestal width (width ~ beta_pol,ped^0.5) to predict the pedestal pressure $p_{\\mathrm{ped}}$. Determine what additional physics (separatrix density and neutral fueling, microtearing or electron-temperature-gradient transport, resistive and diamagnetic effects) is needed to predict $p_{\\mathrm{ped}}$ to within 20 percent at high separatrix density, high gas fueling and metal walls, and give the prediction for ITER $Q = 10$. An answer is a model validated on at least three devices including a metal-wall one.","problem_ref":null,"references":"","settled_by":"Blind pedestal predictions agreeing with measured $p_{\\mathrm{ped}}$ within 20 percent on multiple devices, including high-fueling metal-wall discharges, followed by ITER H-mode data.","status_note":"EPED-type models reproduce pedestal heights in many conventional H-modes but miss the degradation seen at high fueling and separatrix density, as in metal-wall JET; no accepted extension was known as of mid-2026.","title":"Predicting pedestal pressure height and width in reactor conditions","topic_ref":"037681ebe2f068d361e19b0b90c7ad8b9281d3aee6de68370b6a285f803d9ac9"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"79dbbc0e14a97d571b7f3f3f7752be0d6cddb2467c7732ab244756d997a28193","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"8162b323b0893e72b8fa8e3168b6bb68a9d66cb0c41cd873789f7cb8a76a2bf9","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"k5UaIrIIQr80wS0i-MRJod5dFQB9n7BUlWWSbTES9HJDiRz7FH-ZFkS0JckiswwJWcxL2QSpbFMPkVWlO4I8Bg"},"schema":"pubphys.envelope/1"},"record_hash":"79dbbc0e14a97d571b7f3f3f7752be0d6cddb2467c7732ab244756d997a28193","leaf_index":1834}