{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"9d739fe1411336cdff698154a9bb71a352a3f1d24b07f5d143e1347b3402c7e1","created":"2026-10-03T07:17:56Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"25a6a09c3bac3ed6b206b908844095dc4adb88d0e9a03c6b21c23a1e5e5cb2e1","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"beams.rf-breakdown.initiation-mechanism","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"Breakdowns start at small spots on a polished copper surface, but which process lights the spark (electrons pulled out by the field, crystal defects moving to the surface, local melting) is not agreed.","posed_since":"","precise":"In Cu accelerating structures at 3-30 GHz, breakdown occurs at surface fields $eE_{s} \\sim 2-3\\,\\mathrm{MeV}/\\mathrm{cm}$, and Fowler-Nordheim fits of dark current give field-enhancement factors $\\beta \\sim 30-100$ although no protrusions of matching height are observed. Identify the sequence of processes (dislocation-driven surface roughening, field-emission heating of emitters, neutral evaporation, plasma ignition) that turns an intact surface into an arc, with a model that predicts the threshold field and its dependence on hardness and crystal structure of the metal.","problem_ref":null,"references":"","settled_by":"In-situ imaging of breakdown sites before and after the event together with a model that reproduces measured thresholds for at least two metals of different crystal structure.","status_note":"","title":"Microscopic mechanism that initiates vacuum RF breakdown on copper","topic_ref":"29c52025bad0f3bb40505db955939f35befc6ea9256f5e4972142fac9de7c602"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"010d2ae9b6af71dc96488853d420978ccd8287facc6333282924bcb157f63c4f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"c85cb59bd4d0e37a9b015a38f79120b5c77b7cb2294b4ed70b83417201d372ac","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"FhOEG-vHRnoa11Y9qf0fFwN6flq8cC7lvKjvagwhWJoHzTHqT2rOWCap_H-660zvyH9_mwMmkx7nqTwPRFiSCw"},"schema":"pubphys.envelope/1"},"record_hash":"010d2ae9b6af71dc96488853d420978ccd8287facc6333282924bcb157f63c4f","leaf_index":690}