{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"bc6bd3fe35489481f6a8030b380b2a13dfb319bb8e7f23945cc36398a2df04c2","created":"2026-10-03T07:18:08Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"7380569c14895ee27bfa4b1135d795fa90f3640d01ff55e50570c9a3729d4593","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"plasma.exb-low-temperature.anomalous-mobility-closure","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"Thruster simulation codes currently need a hand-tuned correction factor for how easily electrons cross the magnetic field. A formula derived from physics would make the codes predictive.","posed_since":"","precise":"In Hall thrusters (radial $B$ of order 100 to 300 G, xenon propellant), the measured cross-field electron mobility exceeds the classical collisional value by one to three orders of magnitude and varies along the channel. Derive a closure mu_perp(z) from local plasma parameters that, inserted in fluid or hybrid codes, predicts thrust, discharge current and breathing-mode oscillations to within 10 percent without tuning, across thrusters and operating points.","problem_ref":null,"references":"","settled_by":"A closure that predicts measured performance of at least two different thrusters across operating points without adjustment.","status_note":"3D particle-in-cell simulations in 2025-2026 resolve the electron drift instability and near-wall transport paths (e.g. arXiv:2603.14849), but no tuning-free closure exists.","title":"First-principles closure for cross-field electron mobility in Hall thrusters","topic_ref":"0df27ef69105e55adf69d4d0c5a12981d908dd6ae2aae29332a8515dac4c6272"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"cb5159aa4dd4a2477252029cc26eb709ba146ebcc08c01401fa20398fa2d68f4","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"7854a757e21f049fd547ca8a645237c0a7584d5b31ce35c1235fc5ed4b2c4237","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"kvR5ck2kknlyE1WwfHxlA3RqCQWYE1UUYn8-N-ZBeiZmjbE1QvQ_37OxYV6m4bmF201zRhOWMVk8pqgwk_L3DQ"},"schema":"pubphys.envelope/1"},"record_hash":"cb5159aa4dd4a2477252029cc26eb709ba146ebcc08c01401fa20398fa2d68f4","leaf_index":1836}