Integrated ELM Simulation with Edge MHD Stability and Transport of SOL‐Divertor Plasmas

Hayashi, Nobuhiko; Takizuka, T.; Aiba, N.; Ozeki, T.; Oyama, N.

doi:10.1002/ctpp.200810035

Cited by 3 publications

(2 citation statements)

References 20 publications

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“…The minimum value of the energy loss at p in /p ped = 0.53 (closed circle with lower value), in which the subsequent instabilities arise far from the separatrix, is a little larger than that obtained by taking account of only the first instability (open circle). The dependence of the minimum energy loss on p in /p ped is almost the same as that found in [25], in which only the first instability was taken into account and the density was not yet solved. As shown in figure 11, a steep pressure gradient in the core beyond the pedestal top enhances the ELM energy loss by both the extension of the ELM enhanced transport in the first instability and the subsequent instability near the separatrix.…”

Section: Dependence Of Elm Energy Loss and Cycle On The Pressure Grad...supporting

confidence: 57%

Integrated simulation of ELM energy loss and cycle in improved H-mode plasmas

Hayashi¹,

Takizuka²,

Aiba³

et al. 2009

Nucl. Fusion

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The energy loss due to an edge localized mode (ELM) crash and its cycle have been studied by using an integrated core transport code with a stability code for peeling–ballooning modes and a transport model of scrape-off-layer (SOL) and divertor plasmas. The integrated code reproduces a series of ELMs with the following characteristics. The ELM energy loss increases with decreasing collisionality and the ELM frequency increases linearly with the input power, as seen in experiments of type-I ELMs. A transport model with the neoclassical transport in the pedestal connected to the SOL parallel transport reproduces a lowered inter-ELM transport in the case of low collisionality so that the ELM loss power is enhanced as observed in experiments. The inter-ELM energy confinement time evaluated from simulation results agrees with the scaling based on the JT-60U data. The steep pressure gradient in the core just beyond the pedestal top, desirable for improved H-mode plasmas with the H H98y2 factor above unity, is found to enhance the ELM energy loss and reduce the ELM frequency so that the ELM loss power remains constant. The steep pressure gradient in the core beyond the pedestal top broadens eigenfunction profiles of unstable modes and possibly induces subsequent instabilities. In the subsequent instabilities, when a large energy is transported to the vicinity of the separatrix by the instabilities, a subsequent instability arises near the separatrix and makes an additional loss.

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Section: Dependence Of Elm Energy Loss and Cycle On The Pressure Grad...supporting

confidence: 57%

Integrated simulation of ELM energy loss and cycle in improved H-mode plasmas

Hayashi¹,

Takizuka²,

Aiba³

et al. 2009

Nucl. Fusion

Self Cite

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“…The collisionality dependence in the simulation result is comparable to that observed in the experiments. Additionally, TOPICS-IB predicted that the steep core pressure gradient just inside the top of the pedestal broadens the eigenfunction profiles of unstable modes, which results in the enhancement of energy loss [13,14]. The detailed dependence of the MHD mode structure on the core pressure profile inside the top of the pedestal was studied using the linear code MARG2D [15].…”

Section: Introductionmentioning

confidence: 99%

Effect of core pressure gradient just inside the top of the pedestal on the energy loss due to the edge localized mode in JT-60U

Hayashi¹,

Oyama²,

Takizuka³

et al. 2011

Nucl. Fusion

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The effect of core pressure gradient just inside the top of the pedestal on the energy loss due to type-I edge localized modes (ELMs) is studied. An analysis of the experimental data from JT-60U shows that the ELM energy loss normalized by the pedestal stored energy increases with the pressure gradient inside the top of the pedestal normalized by the pedestal pressure gradient. The dependence of normalized ELM energy loss on the normalized pressure gradient inside the top of the pedestal is similar to that predicted by the integrated code TOPICS-IB. The stability of linear ideal MHD modes is analysed using experimental profiles. It is found that the steep core pressure gradient inside the top of the pedestal broadens the eigenfunction profiles of unstable modes inwards. The TOPICS-IB simulation predicted that this broadening can enhance the ELM energy loss.

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