{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"51d5282d98428ec895a7334893fe406f8969b21aeb1df6653b6ec18924be9144","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5d1efa61f8a5cf2bb1992f7873ae2d4cb1c17df9c7d58978aa15b5876db768f5","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"f62386351f348b0605ea09da053416e57d29772c7247ea32d9249013f025276b","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"beams.sc-magnets.stress-degradation-limit","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"$\\mathrm{Nb_3Sn}$ is brittle, and the huge magnetic forces in a high-field magnet squeeze the cable until its ability to carry current is permanently damaged; where that threshold lies and what breaks first is uncertain.","posed_since":"","precise":"Rutherford cables of $\\mathrm{Nb_3Sn}$ filaments in epoxy-impregnated coils at fields up to $\\sim 1.6 \\times 10^{5}\\,\\mathrm{G}$ are under transverse stress of order $1.5 \\times 10^{9} \\text{ to } 2 \\times 10^{9}\\,\\mathrm{dyn}/\\mathrm{cm}^{2}$ (approximate). Determine the stress at which the critical current degrades irreversibly, its dependence on filament layout, impregnation and temperature cycling, and the microscopic failure mode (filament cracking, void collapse, debonding), as a function that fixes the maximal practical dipole field.","problem_ref":"5d1efa61f8a5cf2bb1992f7873ae2d4cb1c17df9c7d58978aa15b5876db768f5","references":"","settled_by":"Critical-current measurements of cable stacks under calibrated transverse stress, combined with post-test microscopy of filament cracks and a model that reproduces the onset stress.","status_note":"","title":"Transverse-stress limit for irreversible degradation of $\\mathrm{Nb_3Sn}$ cables","topic_ref":null},"content_withheld":"false","files":[],"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"61e82fb05c4f969ccaceb183a570e2e223538c8a65e3cd2b6aae4a5f31534460","schema":"pubphys.attested/1"},"id_token":null,"id_token_withheld":"false","envelope":{"attested_hash":"6237ea90de93cacb1a6c5bfaa2b805fbf799dd770cd4b48fabe38e2be23f49d0","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"Vat8QAefvxuxWfgh2vrGIRd9K_h2GVHxBVBJrTNwF3aCeI1rHU4eyoSekSw7nWu29cqORQeRIaIHFrSLPIvKCg"},"schema":"pubphys.envelope/1"},"ots":{"attested":["AE9wZW5UaW1lc3RhbXBzAABQcm9vZgC_ieLohOiSlAEIYjfqkN6TyssabFv6orgF-_eZ3XcM1LSPq-OOK-I_SdDxIGIYFWK3ZcQYGfRlUav82ObvK3_5hLXE2s__zWyZRtk9CPEg_rcK-VWjQzZaobmIRpejJkbZQxhTqvL7eb4gkVeDhRQI8SCoc2WO7-DPY1nWGZFFZ2gsaoFThWU87NFBgB2mgOs_qgjwICQpEHCpNRuM7TZEb-jGD5u7i0NY9ANRzs96cpuNjA34CPEgSBCY6nk9meSCpsIgqugtgUS928s-u_enlO65LhBbZwgI8CDSTi3UbP9XXsgIMxDLkvmBMs90bVBKmRvZEYKuvTOdywjwIOBhAE_usQZ2nBBNY4wzw4-dYOTzn3zDoB6qJnk6bujrCPAgNWsj73C-FdBKnM-YIq56Rzi4rZw0zXjVnprUdC52gz4I8SBcP9hQb3hxUiLf8dFx-DuqZHA2xkmG-c_qCFt8QfQHCAjwIOv_x0B6HyZ6WMHKeIf_d_EUIvwPGdZeVY-hXN3RLDM5CPEgHd9u6OIGCvUV12A1B1xdiOprSJ-4w0cqwfe7CzVX5HsI8CDQo_sIWZiWXaTGRSQBLmU-lHJKskYKqsjO1r02DhB8LAj_8Ajn9YmozHwo9QjwEJ46aM9ZDv3TdtqV3ZbRsNgI8SBOF8pILGf1kodr5MKmQs6Cd93joraGn3g6UPt_-kewPwjwIOG-gmM7bd_eR4AiDMNfluS3xvr7vicLR-sCBr5qtG2cCPAgrVNFrCoeQcCxhlmnE0BzHgR8HQpZAlfqzDDFzfWb8GUI8QRq0WWT8AjZJ2cF_c7k8ACD3-MNLvkMjiwraHR0cHM6Ly9ib2IuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZ_AI9ZMS1zxd7IEI8BDd00WgJZ0RncsC1Fyai_4aCPEgvxMFrnu7F05IW5INiraQ3OVEYMjNx6JfBxw1Q4jPLi4I8QRq0WWS8Ag2zxPAtI5JsP8Ag9_jDS75DI4uLWh0dHBzOi8vYWxpY2UuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZwjxIHAnv4KFFf4uiYEFJvLxiMxSyz8VowJP4roTfDD9h7bICPAgj5tgvbNF7mxSP4jGGE66ezUFRLnI4g1VTkvuV4VtCPAI8CCxlc1HuKORuHgn7DYIYcDhc4oo99OkTWBEvddBypoa7AjwIFcjjaF8kDNDYCZGaNISlRjvX-I7in-QNwsr4JYQbFJvCPAgnl0k4gs7LuY5i1umiHO-J7My3uBThLJUWQoY9LdVSrQI8SA6-Ft11_K_GqMNWYhkVsVqCFvXSYbp4S8JoLsLBnUzvgjxIBC8_mAE7JBP35SNxDBcG7joLJwURpMxdV2vSO64_jEOCPEge04Coj1xSi7CE8UwqiBGNhPyZ5QdD_YZwn-heSdObU4I8SBgdDSgr3VUx1j8m_pK7-OzMwwFgXeLy43ujffCv-hf5AjwIMl-PnAt4xjoBEVU4-nkyN0NKRa9AvX4kEMfllFyIJS9CPFZAQAAAAHz4rV-uwQFg02bVnEMUFgpIdGKjM4tWuID1kTVnrjisAAAAAAA_v___wJURAIAAAAAABYAFBFys2oc0-U-bYrC3VulGLzND5fbAAAAAAAAAAAiaiDwBHLTDgAICPEgMJIBYi46xOIuFDwzJ9nOx14ngW5HbglUf65ORpkoIYcICPAgHgGWEGCDHWgscwT92NOoJ7s-ezbPkyiWr2RnYZDC_dwICPAgtffMyyLu-MscJsDc0dzwGspwSrrmvVAnMNgsgWhHClgICPAgMUl1OfBDUwhp5VZjHwVA0nuz1F5HZTUJCHAnM1L1F3MICPAgStK7UWpnrUueV5EaE7uE0y6BLMp6EANmrbhrTqEBZu8ICPAg5LVW7IHtUL5mNOvPx1hOTfLMmqlQ7t9EFW-KDtrISIQICPAgABgXZ6upFU8qiDQKFtQFpqkjKwl0PsxM4JUjVLlDKbkICPAgEwb96FiOhjlbwI8GFZQ4a5GXwxs4bUdqVOMKrtBWV30ICPEgqBg-wp0c8CAPV9k6J7wIa9_GtQfpWmhpE1zqFZyi2pQICPAg2pZLTVPGJbriiz0UhMytYDVYAXOgQnWDcrMOewK9O8cICPEgxm3QwzbvT4siJzubQGnST67bWv-exYwSPP1KDi7CaUwICPEgm6udUudfjUaM0gUFTylKGDMypj7ptMTG0zmxd_T5yTcICPAgMpOInkjFCVp1pOZhfZnyPAl8hdWGmHzQcrGLgLwSKLgICAAFiJYNc9cZAQPzpjs"],"envelope":["AE9wZW5UaW1lc3RhbXBzAABQcm9vZgC_ieLohOiSlAEIM2PaCsLkZUt3Xot4za7VSMNdoOXAhbui6teSg6MzENbxIDNQtbN8_EV2gMptE7_QtQMsbumoXOkNgu68NjLulVzECPEgAGGLWpfnoZDmsQ8gOvkvW-EIyEIX71UbW82pLJ-WtpsI8SCdFDQjJ_qlwBkqKcED0dzyF-qHEcbXieMXfEc_rSl22AjxIBMY_egHYkw6uDadj8mXp5SuYWh2PITHdulP5ze138keCPAgxLMsAJRr1n56uF8uFZ5h8AB9cntUSaBElUhW_eCLFTUI8SCF20PF3d9YpXmw012QE94VYZkPnoUIwyF2Pq0nRaL_hAjwIEy6JN28xxcmaT8U-CrGm2ycCSQBCZNWkpcJmM3XNqJ2CPEgET84erh4QMqfDxFWGLBJaZS5EYFN7oYAm7iWbswJgxQI8CDsCcIzBovmyR1v7IXhYg1Z7m0X4dWZvLS_NU94HSk3sQjxIJdQdDsL3v2lA7qZb8kMJtOgaTQmbgchdPcS5lYJqDLnCPAgkPXX-naXR0fRIdS-sEDlzYmtMvSCNH42ESUF0QXb6NUI8CDQo_sIWZiWXaTGRSQBLmU-lHJKskYKqsjO1r02DhB8LAj_8Ajn9YmozHwo9QjwEJ46aM9ZDv3TdtqV3ZbRsNgI8SBOF8pILGf1kodr5MKmQs6Cd93joraGn3g6UPt_-kewPwjwIOG-gmM7bd_eR4AiDMNfluS3xvr7vicLR-sCBr5qtG2cCPAgrVNFrCoeQcCxhlmnE0BzHgR8HQpZAlfqzDDFzfWb8GUI8QRq0WWT8AjZJ2cF_c7k8ACD3-MNLvkMjiwraHR0cHM6Ly9ib2IuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZ_AI9ZMS1zxd7IEI8BDd00WgJZ0RncsC1Fyai_4aCPEgvxMFrnu7F05IW5INiraQ3OVEYMjNx6JfBxw1Q4jPLi4I8QRq0WWS8Ag2zxPAtI5JsP8Ag9_jDS75DI4uLWh0dHBzOi8vYWxpY2UuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZwjxIHAnv4KFFf4uiYEFJvLxiMxSyz8VowJP4roTfDD9h7bICPAgj5tgvbNF7mxSP4jGGE66ezUFRLnI4g1VTkvuV4VtCPAI8CCxlc1HuKORuHgn7DYIYcDhc4oo99OkTWBEvddBypoa7AjwIFcjjaF8kDNDYCZGaNISlRjvX-I7in-QNwsr4JYQbFJvCPAgnl0k4gs7LuY5i1umiHO-J7My3uBThLJUWQoY9LdVSrQI8SA6-Ft11_K_GqMNWYhkVsVqCFvXSYbp4S8JoLsLBnUzvgjxIBC8_mAE7JBP35SNxDBcG7joLJwURpMxdV2vSO64_jEOCPEge04Coj1xSi7CE8UwqiBGNhPyZ5QdD_YZwn-heSdObU4I8SBgdDSgr3VUx1j8m_pK7-OzMwwFgXeLy43ujffCv-hf5AjwIMl-PnAt4xjoBEVU4-nkyN0NKRa9AvX4kEMfllFyIJS9CPFZAQAAAAHz4rV-uwQFg02bVnEMUFgpIdGKjM4tWuID1kTVnrjisAAAAAAA_v___wJURAIAAAAAABYAFBFys2oc0-U-bYrC3VulGLzND5fbAAAAAAAAAAAiaiDwBHLTDgAICPEgMJIBYi46xOIuFDwzJ9nOx14ngW5HbglUf65ORpkoIYcICPAgHgGWEGCDHWgscwT92NOoJ7s-ezbPkyiWr2RnYZDC_dwICPAgtffMyyLu-MscJsDc0dzwGspwSrrmvVAnMNgsgWhHClgICPAgMUl1OfBDUwhp5VZjHwVA0nuz1F5HZTUJCHAnM1L1F3MICPAgStK7UWpnrUueV5EaE7uE0y6BLMp6EANmrbhrTqEBZu8ICPAg5LVW7IHtUL5mNOvPx1hOTfLMmqlQ7t9EFW-KDtrISIQICPAgABgXZ6upFU8qiDQKFtQFpqkjKwl0PsxM4JUjVLlDKbkICPAgEwb96FiOhjlbwI8GFZQ4a5GXwxs4bUdqVOMKrtBWV30ICPEgqBg-wp0c8CAPV9k6J7wIa9_GtQfpWmhpE1zqFZyi2pQICPAg2pZLTVPGJbriiz0UhMytYDVYAXOgQnWDcrMOewK9O8cICPEgxm3QwzbvT4siJzubQGnST67bWv-exYwSPP1KDi7CaUwICPEgm6udUudfjUaM0gUFTylKGDMypj7ptMTG0zmxd_T5yTcICPAgMpOInkjFCVp1pOZhfZnyPAl8hdWGmHzQcrGLgLwSKLgICAAFiJYNc9cZAQPzpjs"]},"log":{"leaf_index":"2524","tree_size":"3804","proof":["7952f1aa621468bc271d4fa368007b8a9ddb3b5a061b39eaccfb354273e80fb5","9f48aab1726bccdc4feac0e3d674f88d1b3e6d787c0b55191929f09417f0ccb3","d7a0e33c7cbda49f4176a2e7572eb782570345576c9724066b0d59308496f0ed","a1d6bf2518ee8e25c243cb47ebe74ab5442ce557f2574accb0f714e558f69101","7b27cf6b310fe2f4e92f993be1e629e5f5474dcdb7e016a90cb35c4d42a7ad51","93e989eb5afccf6bd159e36aa811aa8ef30289d271f3d15eb59667f4267f8193","7c0747095d37385fe6f4d152c1a4f15f2c176d36931329cf6ad82b081e9f63f6","193f7e120934503cd45d11622182f80d8b1635765c3becdc1c2cab15bb00bcc2","ad2bf8922b230304eb5887f66a1631d0d013048aef3d1e5c2bce55da65e76cef","453fe2db8b5276d732edac85634e8be036b4709a91a2584f32a4b9edcc8ca9de","325287f5a43e4f3ad4072ec4bd53d43c50c1393021a056122e9cb0fad83b868f","3c578dccc15502c5f3efe228cadc99fee76ab536ed01f66b14d316fdcc157429"],"checkpoint":"pubphys.com/log/v1\n3804\nAK6t4qgu96+M9wScTrIlsJ10d/zhKVEtYguyM3aeJvo=\n\n— pubphys.com/log/v1 JFPwIPP8EtoxgcsQg7V7CwIdL4UKPqJtpv+eB8sFNJjyQHIdyA1VabmBsPyLqq2bLxJPn57rA6fQi8y0QDDjRXHvlQg=\n","promise":"pubphys.com/log/v1 promise\n49daebb3eb24d5b31c02f897511b5ab1464716fc94cd265dd9541bff8b3d1641\n2524\n2026-10-15T23:43:57Z\n2026-10-16T01:43:57Z\n\n— pubphys.com/log/v1 JFPwIH3KQ/tC4GwOMqmmOToKdoxmv/OT02zQrEydt2ARV+RMdOWlruCdWvt7JNi/esTw0UVHndprwXwfwKgt4j4G1w0=\n"},"orcid_key_evidence":[],"attesting":null}