{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"64e115fb9845c70b5f2a026dbb8c575e9c0c127c85dc957f972161494d1ea659","created":"2026-10-03T07:17:56Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"33ccacbf07b2c9f06aec31ea82c3748edbe41d1ed92b3d6e45486bb5fa0485c2","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"beams.advanced-structures.efficiency-instability","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"A driving bunch hands energy to a trailing bunch through the wake it leaves; taking more energy also makes the trailing bunch wobble sideways and break up.","posed_since":"2017","precise":"For a collinear dielectric or corrugated-pipe wakefield accelerator, a relation between drive-to-witness energy-transfer efficiency $\\eta$ and the transverse wake that drives beam breakup was derived around 2017-2018. Determine the maximal $\\eta$ achievable at transformer ratio $R \\ge 5$ with witness emittance growth below 10 percent over the full accelerator length, including BNS damping (energy-chirp detuning of the transverse motion) and quadrupole-wake focusing, or prove an upper bound on $\\eta$.","problem_ref":null,"references":"","settled_by":"An analytic bound or a converged start-to-end simulation with full $3\\mathrm{D}$ wakes, checked by a multi-meter experiment at the stated $R$ and $\\eta$.","status_note":"","title":"Maximum efficiency of a stable collinear structure wakefield accelerator","topic_ref":"b7298016c1710150668f62e56e87b36d9f62eb89c17a03f22442da1d6e9f7f80"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"21b99fe59621d7f82ca9d4fd506b5e4ff8d3aa7c18f433463429ac0c9c451bed","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"7c98eba724f89aa3cd46d31b1411f25dc0ee1c0b975771223c608f2e25528b4d","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"i0km5rowTbUmOtoddW-53SxwEUAf_d3s2TuoH4OaEGynxBifEvfXfExoxciRiDAv68MA6A0f5j7z6hHf_s-oCQ"},"schema":"pubphys.envelope/1"},"record_hash":"21b99fe59621d7f82ca9d4fd506b5e4ff8d3aa7c18f433463429ac0c9c451bed","leaf_index":644}