Edge Localized Modes: Difference between revisions
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<ref>[http://dx.doi.org/10.1088/0741-3335/38/2/001 H. Zohm, ''Edge localized modes (ELMs)'', Plasma Phys. Control. Fusion '''38''' (1996) 105-128]</ref> | <ref>[http://dx.doi.org/10.1088/0741-3335/38/2/001 H. Zohm, ''Edge localized modes (ELMs)'', Plasma Phys. Control. Fusion '''38''' (1996) 105-128]</ref> | ||
<ref>[http://dx.doi.org/10.1016/S0022-3115(97)80039-6 D.N. Hill, ''A review of ELMs in divertor tokamaks'', Journal of Nuclear Materials '''241-243''' (1997) 182-198]</ref> | <ref>[http://dx.doi.org/10.1016/S0022-3115(97)80039-6 D.N. Hill, ''A review of ELMs in divertor tokamaks'', Journal of Nuclear Materials '''241-243''' (1997) 182-198]</ref> | ||
== Physical mechanism == | |||
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> | |||
* Coupled peeling-ballooning modes <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> | |||
* [[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> | |||
* Peeling modes <ref>[http://link.aip.org/link/?APCPCS/871/87/1 C.G. Gimblett, ''Peeling mode relaxation ELM model'', AIP Conf. Proc. '''871''' (2006) 87-99]</ref> | |||
== ELMs and machine operation == | == 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), | Although Quiescent H-modes exist (without ELMs), | ||
<ref>[http://link.aip.org/link/?PHPAEN/12/056121/1 K.H. Burrell et al, ''Advances in understanding quiescent H-mode plasmas in DIII-D'', Phys. Plasmas '''12''' (2005) 056121]</ref> | <ref>[http://link.aip.org/link/?PHPAEN/12/056121/1 K.H. Burrell et al, ''Advances in understanding quiescent H-mode plasmas in DIII-D'', Phys. Plasmas '''12''' (2005) 056121]</ref> | ||
Revision as of 19:57, 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:
- Nonlinear interchange modes [3]
- Coupled peeling-ballooning modes [4]
- Self-Organised Criticality [5]
- Flux surface peeling [6]
- Peeling modes [7]
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), [8] 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. [9]
References
- ↑ H. Zohm, Edge localized modes (ELMs), Plasma Phys. Control. Fusion 38 (1996) 105-128
- ↑ D.N. Hill, A review of ELMs in divertor tokamaks, Journal of Nuclear Materials 241-243 (1997) 182-198
- ↑ A Takayama and M. Wakatani, ELM modelling based on the nonlinear interchange mode in edge plasma, Plasma Phys. Control. Fusion 38 (1996) 1411-1414
- ↑ P.B. Snyder et al, Edge localized modes and the pedestal: A model based on coupled peeling–ballooning modes, Phys. Plasmas 9 (2002) 2037
- ↑ R. Sánchez et al, Modelling of ELM-like phenomena via mixed SOC-diffusive dynamics, Nucl. Fusion 43 (2003) 1031-1039
- ↑ E.R. Solano et al, ELMs and strike point jumps, Journal of Nuclear Materials 337-339 (2005) 747-750
- ↑ C.G. Gimblett, Peeling mode relaxation ELM model, AIP Conf. Proc. 871 (2006) 87-99
- ↑ K.H. Burrell et al, Advances in understanding quiescent H-mode plasmas in DIII-D, Phys. Plasmas 12 (2005) 056121
- ↑ 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