{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"4ed613a8090a95f0d34abc9510bd88bb4ceab43fb44301b39e048f04b35ef9ed","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":["ai:gpt-5.5"],"kind":"seed"},"parents":["8f19874020f3124376226da8c9b84816697d2055d998e03fc7094418cf746c1e","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"2c059043609f0e6df7f9eb6db941000e493a9461bc1d9f714f00ecf226939f1c","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":["ai:gpt-5.5"],"external_id":"plasma.stellarator-optimization.qs-beta-stability","kind":"well-posed","literature_status":"partially-resolved","n":"2","parents":[],"plain":"Quasisymmetry is a hidden symmetry of the field strength that makes particles in a 3D stellarator move as if in a symmetric machine, and it has been achieved almost exactly in vacuum fields. Whether it can be kept while the plasma pressure is high enough for a reactor and the plasma stays stable is unknown.","posed_since":"","precise":"Quasisymmetry ($\\left|B\\right|$ depending on flux-surface angles only through one fixed linear combination) was achieved in vacuum with symmetry-breaking amplitude about $5 \\times 10^{-5}$ of the field strength (about $0.5\\,\\mathrm{G}$ in a $10^{4}\\,\\mathrm{G}$ field; Landreman and Paul, 2022). Determine whether equilibria exist with quasisymmetry error below $10^{-3}$, volume-averaged $\\beta$ of at least $5\\%$, ideal-MHD ballooning and kink stability, and nested flux surfaces, and map the trade-off frontier between these quantities. An answer is explicit configurations or a demonstrated frontier.","problem_ref":"8f19874020f3124376226da8c9b84816697d2055d998e03fc7094418cf746c1e","references":"","settled_by":"Published equilibria verified by independent equilibrium and stability codes, or a systematic frontier showing incompatibility.","status_note":"Finite-$\\beta$ precisely quasisymmetric equilibria were reported after 2022; simultaneous stability at reactor $\\beta$ is not established.","title":"Precise quasisymmetry together with MHD stability at reactor pressure","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"93a5c4e73b4e71df426d914393b66bac952e96038f4e4a9ba9ee551a940f6e33","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"3b211bd1f668b5d5ea6fb2457a36fad8b5b12f9f20491d6da83c447b16f1882d","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"UWU0cUJk3ZT6YN5Oczfp6j-qgzLXNfNbmHn-aD5oMVstVBdr8ysQbThkD6fAMWrTjd-MzB2odtSRv0ZKstLGCw"},"schema":"pubphys.envelope/1"},"record_hash":"93a5c4e73b4e71df426d914393b66bac952e96038f4e4a9ba9ee551a940f6e33","leaf_index":3608}