JOPSS - Search Results

Journal Articles

Kinetic modelling of divertor fluxes during ELMs in ITER

Hosokawa, Masanari*; Loarte, A.*; Huijsmans, G.*; Takizuka, Tomonori*; Hayashi, Nobuhiko

Europhysics Conference Abstracts (Internet), 38F, p.P5.003_1 - P5.003_4, 2014/06

http://ocs.ciemat.es/EPS2014PAP/pdf/P5.003.pdf

Journal Articles

Two-dimensional full particle simulation of the flow patterns in the scrape-off-layer plasma for upper- and lower-null point divertor configurations in tokamaks

Takizuka, Tomonori; Shimizu, Katsuhiro; Hayashi, Nobuhiko; Hosokawa, Masanari*; Yagi, Masatoshi*

Nuclear Fusion, 49(7), p.075038_1 - 075038_9, 2009/07

https://doi.org/10.1088/0029-5515/49/7/075038

Times Cited Count：24 Percentile：66.57(Physics, Fluids & Plasmas)

Plasma flow in the SOL plays an important role for the particle control in magnetic fusion reactors. To study SOL flow patterns, we perform simulations with a full particle code, PARASOL. For upper-null divertor configuration with ion drift away from the null point, the flow is directed to inner and outer plates. The stagnation point is located symmetrically at the bottom. On the other hand for lower-null case with ion drift toward the null point, the flow in outer SOL region has a backward flow pattern. The stagnation point moves below the mid-plane of outer SOL. These simulation results are very similar to experiment. Simulations are carried out by changing the aspect ratio and by artificially cutting the electric field. It is found that the banana motion of trapped ions is important for the formation of flow pattern in addition to the self-consistent electric field. Trapped-ion effects can be stronger than electric-field effects for standard tokamaks with 5.

Journal Articles

Effect of radial transport loss on the asymmetry of ELM heat flux

Takizuka, Tomonori; Oyama, Naoyuki; Hosokawa, Masanari*

Contributions to Plasma Physics, 48(1-3), p.207 - 211, 2008/03

https://doi.org/10.1002/ctpp.200810037

Times Cited Count：4 Percentile：17.4(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Modeling of dynamic response of SOL-divertor plasmas to an ELM crash

Hayashi, Nobuhiko; Takizuka, Tomonori; Hosokawa, Masanari*

Journal of Nuclear Materials, 363-365, p.1044 - 1049, 2007/06

https://doi.org/10.1016/j.jnucmat.2007.01.159

Times Cited Count：12 Percentile：64.14(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Dynamics of SOL-divertor plasmas after an ELM crash in tokamak H-mode plasma

Takizuka, Tomonori; Hosokawa, Masanari*

Fusion Science and Technology, 51(2T), p.271 - 273, 2007/02

https://doi.org/10.13182/FST07-A1372

Times Cited Count：2 Percentile：18.85(Nuclear Science & Technology)

Enhanced particle and heat fluxes to the divertor plates after an ELM crash in H-mode plasmas give the serious load to the plate. We investigate these fluxes with the particle simulation code PARASOL, where an electrostatic PIC method is combined with a Monte-Carlo binary collision model. The electron heat pulse after an ELM crash propagates fast to the plate. Next the ion heat pulse and plasma particle pulse reach the plate slowly with the sound-speed time scale. We study the effect of the ELM-induced-source asymmetry and of the recycling asymmetry on the dynamic behavior of SOL-divertor plasmas. The SOL current plays an important role in the dynamics with the asymmetry.

Journal Articles

Particle simulation of the transient behavior of one-dimensional SOL-divertor plasmas after an ELM crash

Takizuka, Tomonori; Hosokawa, Masanari*

Contributions to Plasma Physics, 46(7-9), p.698 - 703, 2006/09

https://doi.org/10.1002/ctpp.200610066

Times Cited Count：14 Percentile：44.2(Physics, Fluids & Plasmas)

Enhanced heat and particle fluxes to the divertor plates after an ELM crash in H-mode plasmas are the crucial issues for the tokamak reactor operation. Kinetic effect in the transient behaviour of SOL-divertor plasmas for this case is not yet well known. We investigate above problems with an advanced particle simulation code, PARASOL. Dependence of the particle and heat propagations on the collisionality is studied systematically. Effect of the particle recycling is also studied.

Journal Articles

Two-dimensional particle simulation of the flow control in SOL and divertor plasmas

Takizuka, Tomonori; Hosokawa, Masanari*; Shimizu, Katsuhiro

Journal of Nuclear Materials, 313-316(1-3), p.1331 - 1334, 2003/03

https://doi.org/10.1016/S0022-3115(02)01513-1

Times Cited Count：13 Percentile：67.17(Materials Science, Multidisciplinary)

In course of tokamak fusion research, particle and heat control is one of the most crucial issues. Helium ash exhaust and impurity retention in the divertor region owe to the plasma flow towards divertor plate. The localization of heat load on the plate depends on the flow pattern. Accordingly, particle and heat control can be achieved by the proper control of the flow in SOL and divertor plasmas. In this paper, the flow control is studied with two-dimensional particle simulations by PARASOL (PARticle Advanced simulation for SOL and divertor plasmas) code. Magnetic field configuration with separatrix like a tokamak divertor configuration is given. Hot particle source is put in the core plasma. Recycling cold particle source is located near the divertor plate. Particle source of gas puff in the SOL plasma is given for the flow control. Divertor biasing is available by changing the electrostatic potential on the plates. Effects of gas puff and biasing on the flow are studied. Controllability is evaluated from simulation results.

Journal Articles

Asymmetry of dense divertor plasmas influenced by thermoelectric potential and charge-exchange momentum loss

Hayashi, Nobuhiko; Takizuka, Tomonori; Hosokawa, Masanari*; Shimizu, Katsuhiro

Journal of Nuclear Materials, 313-316(1-3), p.1041 - 1045, 2003/03

https://doi.org/10.1016/S0022-3115(02)01534-9

Times Cited Count：2 Percentile：19.1(Materials Science, Multidisciplinary)

Asymmetric equilibria of divertor plasmas influenced by the thermoelectric potential and the momentum loss due to the charge-exchange have been studied by using the five-point model. The momentum loss becomes large when the divertor plasma temperature decreases below about 10 eV. The pre-sheath potential is increased by the momentum loss and compensates for the decrease in the thermoelectric potential at the low-temperature side of the asymmetric equilibrium. Through The change of the pre-sheath potential, the momentum loss has a stabilizing effect on the thermoelectric instability and mitigates the asymmetry. To lower the temperature by the recycling at the one-side divertor, the high recycling and the resultant momentum loss at the other-side divertor are effective because of the bifurcated structure of the equilibrium.

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