{"paper":{"title":"Nitrogen-induced ELM suppression and confinement improvement in the EAST tokamak with a full metal wall","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"Nitrogen seeding achieves ELM-free H-mode in EAST with improved confinement by driving a dissipative trapped electron mode at the pedestal foot that regulates edge gradients and avoids the peeling-ballooning limit.","cross_cats":[],"primary_cat":"physics.plasm-ph","authors_text":"Chu Zhou, Ge Zhuang, Gongshun Li, Hailin Zhao, Jingyan Hu, Jinyue Liu, Kangning Geng, Kedong Li, Peng Shi, Xiang Jian, Yiren Zhu","submitted_at":"2026-04-29T08:12:51Z","abstract_excerpt":"This paper reports the achievement of an ELM-free H-mode regime with confinement improvement enabled by nitrogen (N2) seeding on the Experimental Advanced Superconducting Tokamak (EAST) with a full metal wall. Following N2 injection, large Edge-Localized Mode (ELM) bursts are completely suppressed, while global energy confinement is significantly enhanced, with the H98 factor increasing from approximately 0.9 to 1.2. A distinct edge coherent mode (ECM), localized at the pedestal foot (psi_N ~ 0.99), is identified using O-mode Poloidal Correlation Reflectometry and AXUV diagnostics. This mode o"},"claims":{"count":3,"items":[{"kind":"strongest_claim","text":"Following N2 injection, large ELM bursts are completely suppressed, while global energy confinement is significantly enhanced, with the H98 factor increasing from approximately 0.9 to 1.2. ... The energy and particle transport driven by this pedestal-foot DTEM effectively regulates the edge gradients, preventing the pedestal from crossing the Peeling-Ballooning stability boundary and sustaining a stationary ELM-free state.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That the observed edge coherent mode (20-50 kHz, k_theta ~0.54 cm^-1 at psi_N ~0.99) is a dissipative trapped electron mode whose transport quantitatively prevents the pedestal from crossing the peeling-ballooning boundary, as inferred from linear CGYRO simulations matching experimental diagnostics.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Nitrogen seeding achieves ELM-free H-mode in EAST with improved confinement by driving a dissipative trapped electron mode at the pedestal foot that regulates edge gradients and avoids the peeling-ballooning limit.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"}],"snapshot_sha256":"4a7e9814e14661f6c90ad4f8098469aa8ef81b59b7f6f35df879e074a581b3a7"},"source":{"id":"2604.26403","kind":"arxiv","version":2},"verdict":{"id":"013c5447-ad1e-402e-920f-c2ca42663c87","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-07T11:53:10.375800Z","strongest_claim":"Following N2 injection, large ELM bursts are completely suppressed, while global energy confinement is significantly enhanced, with the H98 factor increasing from approximately 0.9 to 1.2. ... The energy and particle transport driven by this pedestal-foot DTEM effectively regulates the edge gradients, preventing the pedestal from crossing the Peeling-Ballooning stability boundary and sustaining a stationary ELM-free state.","one_line_summary":"Nitrogen seeding achieves ELM-free H-mode in EAST with improved confinement by driving a dissipative trapped electron mode at the pedestal foot that regulates edge gradients and avoids the peeling-ballooning limit.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That the observed edge coherent mode (20-50 kHz, k_theta ~0.54 cm^-1 at psi_N ~0.99) is a dissipative trapped electron mode whose transport quantitatively prevents the pedestal from crossing the peeling-ballooning boundary, as inferred from linear CGYRO simulations matching experimental diagnostics.","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2604.26403/integrity.json","findings":[],"available":true,"detectors_run":[{"name":"ai_meta_artifact","ran_at":"2026-05-21T00:37:24.087247Z","status":"completed","version":"1.0.0","findings_count":0}],"snapshot_sha256":"7d4b28ebefb7b5587af61aaedf152af0b23d2266d2dc584f64a87939af224c3c"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}