{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"b160a37ad1a26a4812eab62b9d3cad058c60aa83b276792f5332ef5c03d0d606","created":"2026-10-03T07:18:08Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"73f7477ab88d75ca5e8004563ecd3ef4a9e7f3acefbe2ae224dba98d2b776ce5","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"plasma.reconnection.collisionless-sheet-onset","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"In Earth's magnetic tail the solar wind slowly stretches a sheet of electric current for about an hour before reconnection suddenly starts and releases a substorm (a burst of auroral activity). A small magnetic field threading the sheet is predicted to stabilize it, and why and when the sheet nevertheless tears is not known.","posed_since":"","precise":"For a current sheet with lobe field $B_0$, small normal field $B_n$ ($B_n/B_0$ about 0.01 to 0.1) and half-thickness $L$ thinned by external driving toward the ion inertial length $d_i$ or below, determine the condition on $L/d_i$, $B_n/B_0$, magnetic flux accumulation at the sheet end and driving rate under which the sheet becomes unstable to collisionless tearing or a related mode (electron tearing, which magnetized electrons are predicted to stabilize; ion tearing; ballooning-interchange modes), and the resulting growth time. An answer is an onset criterion and onset time that agree with fully kinetic simulations at realistic $m_i/m_e$ and with substorm growth-phase observations.","problem_ref":null,"references":"","settled_by":"A criterion confirmed by kinetic simulations of driven sheets and by multi-spacecraft observations (e.g. THEMIS, MMS) of the tail current sheet just before substorm onset.","status_note":"","title":"Collisionless onset of reconnection in a thinning magnetotail current sheet","topic_ref":"c1057caf785ec309864fe9c3911636cf72981d9ad70fccb8c56b4c4d20d44a4f"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"5f9de1423cc1e1a9ad0bbd9fa81d784a5e9c1a574d0bb7dec94d643bde3ea042","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"22693a85981ddb60c8ac0fe7c262903bb5fd5b648c9669652c2cd85277b22b7c","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"ftqWoxpg2BHdnu_7tR9_C-5j2abzAeuFJur4SQ5VxOZ5mTWxOHNxqqHQcC8Faf30srC1CZXshZsiFwnDJoONAw"},"schema":"pubphys.envelope/1"},"record_hash":"5f9de1423cc1e1a9ad0bbd9fa81d784a5e9c1a574d0bb7dec94d643bde3ea042","leaf_index":1859}