Development of Integrated SOL/Divertor Code and Simulation Study in JAEA

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Huge power handling in the SOL/divertor region is one of the crucial issues for a tokamak fusion reactor. Divertor design study of a DEMO reactor with fusion power of 3 GW and ITER size plasma has progressed using the integrated divertor code SONIC. Recently, to improve conversion of the solution for the DEMO divertor plasma simulation, SONIC code has been improved. The calculation time is significantly reduced by (i) the backflow model for the simplified impurity exhaust process and (ii) optimization on HELIOS at BA-IFERC. In the SONIC simulation, the partial detached divertor plasma was obtained by the Ar impurity seeding. Although the plasma heat load at the outer target was reduced by the partial detachment, the contribution of the impurity radiation and the surface recombination of the fuel ions to the target heat load became large. As a result, the peak of the total target heat load was estimated to be 16 MW/m 2 . In order to reduce the total heat load, control of the impurity radiation profile by kind of seeding impurity species and the divertor geometry has been studied. They can decrease the target heat load, but the peak heat load is still larger than the heat removal capability of the present divertor target concept. Further design study including change of the machine specifications is necessary.

Section: Integrated Divertor Code Sonicmentioning

confidence: 99%

“…The important atomic and molecular processes for appropriate treatment of the recycling are taken into account [8].…”

Section: Integrated Divertor Code Sonicmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Divertor Study on DEMO Reactor

Hoshino

Asakura

Shimizu

et al. 2014

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“…The SOL/divertor model consists of transports of SOL/divertor plasmas and of neutrals and impurities, and thus should satisfy many difficult requirements, such as the complex geometry, the atomic and molecular processes of neutrals and impurities. To investigate the SOL/divertor physics, the integrated SOL/divertor code SONIC [8] has been developed by coupling the plasma fluid code SOLDOR [9], the neutral Monte Carlo (MC) code NEUT2D [10] and the impurity MC code IMPMC [11]. The SONIC also can deal with the edge/pedestal region when the core boundary is set inside the edge/pedestal region.…”

Section: Introductionmentioning

confidence: 99%

Integrated Modeling of Whole Tokamak Plasma

Hayashi

Honda

Hoshino

et al. 2011

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Development and integration of models for the whole tokamak plasma have progressed on the basis of experimental analyses and first principle simulations. Integrated models of core, edge-pedestal and scrape-offlayer (SOL)-divertor clarified complex and autonomous features of reactor relevant plasmas. The integrated core plasma model including an anomalous transport of alpha particles by Alfven eigenmodes is developed in the core transport code TOPICS-IB and indicates the degradation of fusion performance. The integrated rotation model is developed in the advanced transport code TASK/TX and clarifies the mechanism of alpha particle-driven toroidal flow. A transport model of high-Z impurities is developed and predicts large inward pinch in a plasma rotating in the direction counter to the plasma current. TOPICS-IB is extended to include the edge-pedestal model by integrating with the stability code, simple SOL-divertor and pellet models, and clarifies the mechanism of pellet triggered ELM. The integrated SOL-divertor code SONIC is further integrated with TOPICS-IB and enables to study and design operation scenarios compatible with both the high confinement in the core and the low heat load on divertor plates.

“…A majority, such as B2 [11], UEDGE [12], EDGE2D [13], and SOLDOR [14] are fluid codes, which reduce the dimensionality by assuming a Maxwellian velocity distribution. However, the fluid model is not self-consistent; it requires closure parameters and boundary conditions inside the sheath region to be given by external models.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Particle Simulation Study of Parallel Heat Transport in Scrape-off Layer Plasmas over a Wide Range of Collisionalities

Froese

Takizuka

Yagi

2010

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Fluid models are not generally applicable to fusion edge plasmas without external provision of kinetic factors: closure parameters and boundary conditions inside the sheath region. We explain the PARASOL-1D simulation, a particle-in-cell code with a binary collision Monte-Carlo model, and use it to determine four kinetic factors commonly needed in fluid codes. These are the electron and ion heat flux limiting factors, α e and α i , the ion adiabatic index, γ A , and the electron and ion temperature anisotropy, T || /T ⊥ . We survey these factors over a wide range of collisionalities and find that, as predicted, the conductive heat flux is accurately described by the Spitzer-Härm expression in the collisional limit and asymptotes to a constant value in the collisionless limit. However, unique behavior occurs in the weakly collisional regime when the ratio of the mean free path to connection length is 0.1 < λ mfp /L || < 10, when the SOL is between the conduction-and sheath-limited regimes. We find that α e can peak, becoming larger than the collisionless limit, γ A is less than unity, and only the ions are anisotropic. The effects of electron energy radiation and Langevin heating are explored. Finally, the strong deviations of the energy distribution function from Maxwellian in the weakly collisional and collisionless regimes are explained.