{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"4e17c67221ac30bd8432c8b9583692d8f60669a8bd071f180e83764aeb05e91e","created":"2026-10-03T07:17:56Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"1a0999a282bf7c3b02a99e6ab448629b280c87172150bf35098b30374c9fa9ab","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"beams.microbunching-fel.gain-prediction","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"Engineers estimate how much the density ripples grow, but measured growth often differs from predictions. A theory that predicts it reliably in three dimensions is missing.","posed_since":"","precise":"For a linac with laser heater, chicanes and transport, predict the microbunching gain spectrum $G(\\lambda)$ for $\\lambda\\sim 0.1\\text{ to }100\\,\\mathrm{micron}$ including 3D coherent synchrotron radiation, longitudinal space charge, intrabeam scattering and transverse-longitudinal coupling. An answer reproduces measured bunching spectra (for example via coherent optical transition radiation) within a factor of two at each wavelength.","problem_ref":null,"references":"","settled_by":"Start-to-end predictions agreeing with measured gain spectra on at least two XFELs without fitted parameters.","status_note":"1D linear gain theory with laser-heater suppression works for gross trends; quantitative 3D agreement is lacking.","title":"Predictive 3D theory of microbunching gain through compressors","topic_ref":"96829e4a8214c58e8270f023e22cde3715fc0dd6fc4307b667881195ee4a7930"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"6367c314d83b4a185cb0ae594f89d7172b9854832278190f50eb28fbd90b798f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"1515fea6266a1965fc83239e6b49cc5f4a1cc817b6b1b2a77136510b7d6d3e1b","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"k34KgMuwLiT8_X5_RZ_kycTmC3euaU4QUQYAlZ8AI67isIvGW8dQlVV-UivbVwjqeOvRKSvj_riIYnplcbwJBg"},"schema":"pubphys.envelope/1"},"record_hash":"6367c314d83b4a185cb0ae594f89d7172b9854832278190f50eb28fbd90b798f","leaf_index":670}