Edge Localized Modes: Difference between revisions

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The physical mechanism of ELMs has not been fully clarified. Several possible explanations have been put forward:
The physical mechanism of ELMs has not been fully clarified. Several possible explanations have been put forward:
* Nonlinear interchange modes <ref>[http://dx.doi.org/10.1088/0741-3335/38/8/046 A Takayama and M. Wakatani, ''ELM modelling based on the nonlinear interchange mode in edge plasma'', Plasma Phys. Control. Fusion '''38''' (1996) 1411-1414]</ref>
* Nonlinear interchange modes <ref>[http://dx.doi.org/10.1088/0741-3335/38/8/046 A Takayama and M. Wakatani, ''ELM modelling based on the nonlinear interchange mode in edge plasma'', Plasma Phys. Control. Fusion '''38''' (1996) 1411-1414]</ref>
* Coupled peeling-ballooning modes <ref>[http://link.aip.org/link/?PHPAEN/5/2687/1 J.W. Connor et al, ''Magnetohydrodynamic stability of tokamak edge plasmas'', Phys. Plasmas '''5''' (1998) 2687]</ref><ref>[http://link.aip.org/link/?PHPAEN/9/2037/1 P.B. Snyder et al, ''Edge localized modes and the pedestal: A model based on coupled peeling–ballooning modes'', Phys. Plasmas '''9''' (2002) 2037]</ref>
* Coupled peeling-ballooning modes <ref>[http://link.aip.org/link/?PHPAEN/5/2687/1 J.W. Connor et al, ''Magnetohydrodynamic stability of tokamak edge plasmas'', Phys. Plasmas '''5''' (1998) 2687]</ref><ref>[http://link.aip.org/link/?PHPAEN/9/2037/1 P.B. Snyder et al, ''Edge localized modes and the pedestal: A model based on coupled peeling–ballooning modes'', Phys. Plasmas '''9''' (2002) 2037]</ref><ref>[http://dx.doi.org/10.1088/0029-5515/49/9/095015 N. Hayashi et al, ''Integrated simulation of ELM energy loss and cycle in improved H-mode plasmas'', Nucl. Fusion '''49''' (2009) 095015]</ref>
* [[Self-Organised Criticality]] <ref>[http://dx.doi.org/10.1088/0029-5515/43/10/003 R. Sánchez et al, ''Modelling of ELM-like phenomena via mixed SOC-diffusive dynamics'', Nucl. Fusion '''43''' (2003) 1031-1039 ]</ref>
* [[Self-Organised Criticality]] <ref>[http://dx.doi.org/10.1088/0029-5515/43/10/003 R. Sánchez et al, ''Modelling of ELM-like phenomena via mixed SOC-diffusive dynamics'', Nucl. Fusion '''43''' (2003) 1031-1039 ]</ref>
* Flux surface peeling <ref>[http://dx.doi.org/10.1016/j.jnucmat.2004.09.067 E.R. Solano et al, ''ELMs and strike point jumps'', Journal of Nuclear Materials '''337-339''' (2005) 747-750 ]</ref>
* Flux surface peeling <ref>[http://dx.doi.org/10.1016/j.jnucmat.2004.09.067 E.R. Solano et al, ''ELMs and strike point jumps'', Journal of Nuclear Materials '''337-339''' (2005) 747-750 ]</ref>

Revision as of 19:12, 31 August 2009

The steep edge gradients (of density and temperature) associated with an H-mode lead to quasi-periodic violent relaxation phenomena, known as Edge Localized Modes (ELMs), which have a strong impact on the surrounding vessel. [1] [2]

Physical mechanism

The physical mechanism of ELMs has not been fully clarified. Several possible explanations have been put forward:

ELMs and machine operation

The occurrence of an ELM leads to a significant expulsion of heat and particles, with deleterious consequences for the vessel wall and machine operation. Although Quiescent H-modes exist (without ELMs), [10] they are generally considered not convenient due to the accumulation of impurities. To achieve steady state, an ELMy H-mode is preferred and this mode of operation is proposed as the standard operating scenario for ITER, thus converting ELM mitigation into a priority. [11]

References

  1. ↑ H. Zohm, Edge localized modes (ELMs), Plasma Phys. Control. Fusion 38 (1996) 105-128
  2. ↑ D.N. Hill, A review of ELMs in divertor tokamaks, Journal of Nuclear Materials 241-243 (1997) 182-198
  3. ↑ A Takayama and M. Wakatani, ELM modelling based on the nonlinear interchange mode in edge plasma, Plasma Phys. Control. Fusion 38 (1996) 1411-1414
  4. ↑ J.W. Connor et al, Magnetohydrodynamic stability of tokamak edge plasmas, Phys. Plasmas 5 (1998) 2687
  5. ↑ P.B. Snyder et al, Edge localized modes and the pedestal: A model based on coupled peeling–ballooning modes, Phys. Plasmas 9 (2002) 2037
  6. ↑ N. Hayashi et al, Integrated simulation of ELM energy loss and cycle in improved H-mode plasmas, Nucl. Fusion 49 (2009) 095015
  7. ↑ R. Sánchez et al, Modelling of ELM-like phenomena via mixed SOC-diffusive dynamics, Nucl. Fusion 43 (2003) 1031-1039
  8. ↑ E.R. Solano et al, ELMs and strike point jumps, Journal of Nuclear Materials 337-339 (2005) 747-750
  9. ↑ C.G. Gimblett, Peeling mode relaxation ELM model, AIP Conf. Proc. 871 (2006) 87-99
  10. ↑ K.H. Burrell et al, Advances in understanding quiescent H-mode plasmas in DIII-D, Phys. Plasmas 12 (2005) 056121
  11. ↑ M.R. Wade, Physics and engineering issues associated with edge localized mode control in ITER, Fusion Engineering and Design 84, Issues 2-6 (2009) 178-185
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