{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"52f825773c6800537449f5d864ca81eff5eba311637671cbe221a3bbcf17cf71","created":"2026-10-03T07:18:08Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"ba7c2dd7600ac377719645abea2086bfde8928d83e99797bdfdb20aaedeb1627","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"plasma.wakefield-accelerators.staging-beam-quality","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Each plasma stage can only add a limited energy, so a collider needs many stages in a row. Passing a beam from one stage to the next without losing particles or blurring it has not been demonstrated.","posed_since":"","precise":"Between stages the strongly focused beam diverges and must be refocused, producing chromatic emittance growth $(\\Delta \\epsilon/\\epsilon)^2 \\sim (W \\sigma_{\\delta})^2$ with chromatic amplitude $W \\sim \\beta_{\\mathrm{lens}}/f$. Demonstrate acceleration through at least two independently driven stages with charge coupling above 90 percent, normalized emittance growth below 10 percent and rms energy spread below 1 percent, or show it is impossible with known optics. An answer is an experiment or a proof of a fundamental limit.","problem_ref":null,"references":"","settled_by":"A two-stage experiment with independent drivers meeting the stated charge, emittance and energy-spread metrics.","status_note":"As of 2025 no staging of beam-driven plasma accelerators had been demonstrated; the only two-stage laser-driven test (2016) coupled about 3.5 percent of the charge.","title":"Multistage plasma acceleration with preserved beam quality","topic_ref":"df8d7bd34712d11229b506f6cb66d5f2fe29db346946d9557ff6744f777eb91a"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"e4d754aa436da05222a249b68c4a5237732c303042d29fb62ca0fbe36aeafc7e","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"38231684489d1faae6765cf25a038b33c6c95fdbc8513e823fca9e2f38db662a","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"CmuFX0kTMih4emWGX0ef6yqwYw-LjOTPCYtJIZtf88uwiPBdv5YSWIL15ry-8E4vInnqBx-pAv3hsCy3X8GaDQ"},"schema":"pubphys.envelope/1"},"record_hash":"e4d754aa436da05222a249b68c4a5237732c303042d29fb62ca0fbe36aeafc7e","leaf_index":1885}