An edge-localized mode (ELM) is a plasma instability occurring in the edge region of a tokamakplasma due to periodic relaxations of the edge transport barrier in high-confinement mode. Each ELM burst is associated with expulsion of particles and energy from the confined plasma into the scrape-off layer. This phenomenon was first observed in the ASDEX tokamak in 1981.[1]Diamagnetic effects in the model equations expand the size of the parameter space in which solutions of repeated sawteeth can be recovered compared to a resistive MHD model.[2] An ELM can expel up to 20 percent of the reactor's energy.[3]
In 2006 an initiative (Project Aster) was started to simulate a full ELM cycle including its onset, the highly non-linear phase, and its decay. However, this did not constitute a “true” ELM cycle, since a true ELM cycle would require modeling the slow growth after the crash, in order to produce a second ELM.
As of late 2011, several research facilities had demonstrated active control or suppression of ELMs in tokamak plasmas. For example, the KSTAR tokamak used specific asymmetric three-dimensional magnetic field configurations to achieve this goal.[10][11]
In 2015, results of the first simulation to demonstrate repeated ELM cycling was published.[12]
In 2022, researchers began testing the small ELM hypothesis at JET to assess the utility of the technique.[7][3]
^F., Wagner; A.R., Field; G., Fussmann; J.V., Hofmann; M.E., Manso; O., Vollmer; José, Matias (1990). "Recent results of H-mode studies on ASDEX". 13th International Conference on Plasma Physics and Controlled Nuclear Fusion: 277–290. hdl:10198/9098.
^Halpern, F D; Leblond, D; Lütjens, H; Luciani, J-F (2010-11-30). "Oscillation regimes of the internal kink mode in tokamak plasmas". Plasma Physics and Controlled Fusion. 53 (1): 015011. doi:10.1088/0741-3335/53/1/015011. ISSN 0741-3335. S2CID 122868427.
^ abChoi, Charles Q. (20 October 2022). "Controlled chaos may be the key to unlimited clean energy". Inverse. Retrieved 2022-10-26.
^Lee, Chris (13 September 2018). "A third dimension helps Tokamak fusion reactor avoid wall-destroying instability". Ars Technica. Retrieved 2018-09-17.
^Leonard, A.W. (11 September 2014). "Edge-localized modes in tokamaks". Physics of Plasmas. 21 (9): 090501. Bibcode:2014PhPl...21i0501L. doi:10.1063/1.4894742. OSTI 1352343.
^T.E. Evans; et al. (2008). "RMP ELM suppression in DIII-D plasmas with ITER similar shapes and collisionalities". Nucl. Fusion. 92 (48): 024002. Bibcode:2008NucFu..48b4002E. doi:10.1088/0029-5515/48/2/024002. hdl:11858/00-001M-0000-0026-FFB5-4. S2CID 54039023.
^ abHarrer, G. F.; Faitsch, M.; Radovanovic, L.; Wolfrum, E.; Albert, C.; Cathey, A.; Cavedon, M.; Dunne, M.; Eich, T.; Fischer, R.; Griener, M.; Hoelzl, M.; Labit, B.; Meyer, H.; Aumayr, F. (2022-10-10). "Quasicontinuous Exhaust Scenario for a Fusion Reactor: The Renaissance of Small Edge Localized Modes". Physical Review Letters. 129 (16): 165001. arXiv:2110.12664. Bibcode:2022PhRvL.129p5001H. doi:10.1103/PhysRevLett.129.165001. PMID 36306746. S2CID 239768831.
^"Fusion-reactor instabilities can be optimized by adjusting plasma density and magnetic fields". Physics World. Nov 4, 2022.
^ T.E. Evans; et al. (2004). "Suppression of Large Edge-Localized Modes in High-Confinement DIII-D Plasmas with a Stochastic Magnetic Boundary". Physical Review Letters. 92 (23): 235003. Bibcode:2004PhRvL..92w5003E. doi:10.1103/PhysRevLett.92.235003. PMID 15245164.
^Kwon, Eunhee (2011-11-10). "KSTAR announces successful ELM suppression". Retrieved 2011-12-11.
^Park, Jong-Kyu; Jeon, YoungMu; In, Yongkyoon; Ahn, Joon-Wook; Nazikian, Raffi; Park, Gunyoung; Kim, Jaehyun; Lee, HyungHo; Ko, WonHa; Kim, Hyun-Seok; Logan, Nikolas C.; Wang, Zhirui; Feibush, Eliot A.; Menard, Jonathan E.; Zarnstroff, Michael C. (2018-09-10). "3D field phase-space control in tokamak plasmas". Nature Physics. 14 (12): 1223–1228. Bibcode:2018NatPh..14.1223P. doi:10.1038/s41567-018-0268-8. ISSN 1745-2473. OSTI 1485109. S2CID 125338335.
^Orain, François; Bécoulet, M; Morales, J; Huijsmans, G T A; Dif-Pradalier, G; Hoelzl, M; Garbet, X; Pamela, S; Nardon, E (2014-11-28). "Non-linear MHD modeling of edge localized mode cycles and mitigation by resonant magnetic perturbations" (PDF). Plasma Physics and Controlled Fusion. 57 (1): 014020. doi:10.1088/0741-3335/57/1/014020. ISSN 0741-3335. S2CID 44243673.
Further readingedit
Kirk, A; Liu, Yueqiang; Chapman, I T; Harrison, J; Nardon, E; Scannell, R; Thornton, A J (2013-03-06). "Effect of resonant magnetic perturbations on ELMs in connected double null plasmas in MAST". Plasma Physics and Controlled Fusion. 55 (4): 045007. arXiv:1303.0146. Bibcode:2013PPCF...55d5007K. doi:10.1088/0741-3335/55/4/045007. ISSN 0741-3335. S2CID 119208710.
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An edge localized mode ELM is a plasma instability occurring in the edge region of a tokamak plasma due to periodic relaxations of the edge transport barrier in high confinement mode Each ELM burst is associated with expulsion of particles and energy from the confined plasma into the scrape off layer This phenomenon was first observed in the ASDEX tokamak in 1981 1 Diamagnetic effects in the model equations expand the size of the parameter space in which solutions of repeated sawteeth can be recovered compared to a resistive MHD model 2 An ELM can expel up to 20 percent of the reactor s energy 3 Contents 1 Issues 2 Prevention and control 3 History 4 See also 5 References 6 Further readingIssues editELM is a major challenge in magnetic fusion research with tokamaks as these instabilities can Damage wall components in particular divertor plates by ablating them away due to their extremely high energy transfer rate GW m2 4 Potentially couple or trigger other instabilities such as the resistive wall mode RWM or the neoclassical tearing mode NTM 5 Prevention and control editA variety of experiments simulations have attempted to mitigate damage from ELM Techniques include Application of resonant magnetic perturbations RMPs with in vessel current carrying coils can eliminate or weaken ELMs 6 Injecting pellets to increase the frequency and thereby decrease the severity of ELM bursts ASDEX Upgrade citation needed Multiple small scale ELMs 000s s in tokamaks to prevent the creation of large ones spreading the associated heat over a larger area and interval 7 Increase the plasma density and at high densities adjusting the topology of the magnetic field lines confining the plasma 8 History editIn 2003 DIII D begn experimenting with resonant magnetic perturbations to control ELMs 9 In 2006 an initiative Project Aster was started to simulate a full ELM cycle including its onset the highly non linear phase and its decay However this did not constitute a true ELM cycle since a true ELM cycle would require modeling the slow growth after the crash in order to produce a second ELM As of late 2011 several research facilities had demonstrated active control or suppression of ELMs in tokamak plasmas For example the KSTAR tokamak used specific asymmetric three dimensional magnetic field configurations to achieve this goal 10 11 In 2015 results of the first simulation to demonstrate repeated ELM cycling was published 12 In 2022 researchers began testing the small ELM hypothesis at JET to assess the utility of the technique 7 3 See also editResonant magnetic perturbations used to control ELMs Plasma instability TokamakReferences edit F Wagner A R Field G Fussmann J V Hofmann M E Manso O Vollmer Jose Matias 1990 Recent results of H mode studies on ASDEX 13th International Conference on Plasma Physics and Controlled Nuclear Fusion 277 290 hdl 10198 9098 Halpern F D Leblond D Lutjens H Luciani J F 2010 11 30 Oscillation regimes of the internal kink mode in tokamak plasmas Plasma Physics and Controlled Fusion 53 1 015011 doi 10 1088 0741 3335 53 1 015011 ISSN 0741 3335 S2CID 122868427 a b Choi Charles Q 20 October 2022 Controlled chaos may be the key to unlimited clean energy Inverse Retrieved 2022 10 26 Lee Chris 13 September 2018 A third dimension helps Tokamak fusion reactor avoid wall destroying instability Ars Technica Retrieved 2018 09 17 Leonard A W 11 September 2014 Edge localized modes in tokamaks Physics of Plasmas 21 9 090501 Bibcode 2014PhPl 21i0501L doi 10 1063 1 4894742 OSTI 1352343 T E Evans et al 2008 RMP ELM suppression in DIII D plasmas with ITER similar shapes and collisionalities Nucl Fusion 92 48 024002 Bibcode 2008NucFu 48b4002E doi 10 1088 0029 5515 48 2 024002 hdl 11858 00 001M 0000 0026 FFB5 4 S2CID 54039023 a b Harrer G F Faitsch M Radovanovic L Wolfrum E Albert C Cathey A Cavedon M Dunne M Eich T Fischer R Griener M Hoelzl M Labit B Meyer H Aumayr F 2022 10 10 Quasicontinuous Exhaust Scenario for a Fusion Reactor The Renaissance of Small Edge Localized Modes Physical Review Letters 129 16 165001 arXiv 2110 12664 Bibcode 2022PhRvL 129p5001H doi 10 1103 PhysRevLett 129 165001 PMID 36306746 S2CID 239768831 Fusion reactor instabilities can be optimized by adjusting plasma density and magnetic fields Physics World Nov 4 2022 T E Evans et al 2004 Suppression of Large Edge Localized Modes in High Confinement DIII D Plasmas with a Stochastic Magnetic Boundary Physical Review Letters 92 23 235003 Bibcode 2004PhRvL 92w5003E doi 10 1103 PhysRevLett 92 235003 PMID 15245164 Kwon Eunhee 2011 11 10 KSTAR announces successful ELM suppression Retrieved 2011 12 11 Park Jong Kyu Jeon YoungMu In Yongkyoon Ahn Joon Wook Nazikian Raffi Park Gunyoung Kim Jaehyun Lee HyungHo Ko WonHa Kim Hyun Seok Logan Nikolas C Wang Zhirui Feibush Eliot A Menard Jonathan E Zarnstroff Michael C 2018 09 10 3D field phase space control in tokamak plasmas Nature Physics 14 12 1223 1228 Bibcode 2018NatPh 14 1223P doi 10 1038 s41567 018 0268 8 ISSN 1745 2473 OSTI 1485109 S2CID 125338335 Orain Francois Becoulet M Morales J Huijsmans G T A Dif Pradalier G Hoelzl M Garbet X Pamela S Nardon E 2014 11 28 Non linear MHD modeling of edge localized mode cycles and mitigation by resonant magnetic perturbations PDF Plasma Physics and Controlled Fusion 57 1 014020 doi 10 1088 0741 3335 57 1 014020 ISSN 0741 3335 S2CID 44243673 Further reading editKirk A Liu Yueqiang Chapman I T Harrison J Nardon E Scannell R Thornton A J 2013 03 06 Effect of resonant magnetic perturbations on ELMs in connected double null plasmas in MAST Plasma Physics and Controlled Fusion 55 4 045007 arXiv 1303 0146 Bibcode 2013PPCF 55d5007K doi 10 1088 0741 3335 55 4 045007 ISSN 0741 3335 S2CID 119208710 Tala Tuomas Garbet Xavier 2006 Physics of Internal Transport Barriers PDF Comptes Rendus Physique 7 6 622 633 Bibcode 2006CRPhy 7 622T doi 10 1016 j crhy 2006 06 005 via Elsevier Science Direct Retrieved from https en wikipedia org w index php title Edge localized mode amp oldid 1194762369, wikipedia, wiki, book, books, library,
