Three-dimensional impurity transport modeling of neon-seeded and nitrogen-seeded LHD plasmas

Kawamura, G.; Tanaka, Hirohiko; Mukai, K.; Dai, Shuyu; Masuzaki, S.; Kobayashi, M.; Suzuki, Y.; Feng, Y.

doi:10.1088/1361-6587/aac9ea

Cited by 42 publications

(40 citation statements)

References 34 publications

(53 reference statements)

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“…In the Ne seeded plasmas, both radiation enhancement in the ergodic region and divertor heat load reduction were observed. It is reproduced well by the three-dimensional transport code EMC3-EIRENE [8]. On the other hand, in the Kr seeded plasmas, plasma radiation moved from the edge to the core region gradually.…”

Section: Introductionmentioning

confidence: 64%

Divertor Detachment with Multi-Species Impurity Seeding in LHD

Mukai

Masuzaki

Hayashi

et al. 2020

Plasma and Fusion Research

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Divertor detachment using higher-Z (Kr) and/or lower-Z (Ne) is investigated. Using Kr+Ne superimposed seeding, plasma radiation could be enhanced at the upstream region in the edge plasma with suppression of impurity accumulation toward the core plasma. Here, the pre-seeded Kr emission was drastically enhanced after the subsequent Ne seeding. Moreover, the detachment using Kr+Ne seeding could be stably sustained while the detachment using single species seeding is short-lived. Reduction of edge electron temperature due to Ne seeding can promote the Kr emission at the upstream region. It indicates the availability of multi-species impurity seeding with different cooling rate.

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Section: Introductionmentioning

confidence: 64%

Divertor Detachment with Multi-Species Impurity Seeding in LHD

Mukai

Masuzaki

Hayashi

et al. 2020

Plasma and Fusion Research

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“…In the LHD, studies on the divertor detachment are performed by seeding impurities deliberately [17][18][19] and by applying RMP from special coils [20][21][22]. In this chapter, we focus on the detachment with the RMP application, which is a unique feature of the LHD.…”

Section: Experimental Observations On Detachment In the Heliotron Lhdmentioning

confidence: 99%

“…This is because of a deeper penetration of the NBI due to the shrinkage of the plasma volume with the edge radiation cooling. The increased energy deposition at the central region with RMP, $0.3 MW/m 3 , provides an addition to the particle source density ΔS p of the order of 10 19 1/s/m 3 , estimated for an NBI particle energy of 180 keV. According to a simple picture of a diffusive particle transport, this ΔS p leads to a density increment of Δn$S p Δr 2 =D ⊥ ¼10 17 $10 18 m À3 ,withΔr ≈ 0:1$0:4 m (Δρ ≈ 0:2$0:8), D ⊥ ¼1 m 2 =s.This level is too low to be responsible for the density increase of 10 19 m À3 observed at the plasma axis with RMP, Figure 14(e) and (f).…”

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confidence: 99%

Experimental Studies of and Theoretical Models for Detachment in Helical Fusion Devices

Kobayashi¹,

Tokar²

2020

Fusion Energy

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Good plasma performance in magnetic fusion devices of different types, both tokamaks and helical devices, is achieved normally if the plasma density does not exceed a certain limit. In devices with a divertor, such as tokamaks JET, JT-60U, and heliotron large helical device (LHD), by approaching the density limit, the plasma detaches from the divertor target plates so that the particle and heat fluxes onto the targets reduce dramatically. This is an attractive scenario for fusion reactors, offering a solution to the plasma-wall interaction problem. However, the main concerns by realizing such a scenario are the stability of the detached zone. The activity on the heliotron LHD aimed on detachment stabilization, by applying a resonant magnetic perturbation (RMP) and generating a wide magnetic island at the plasma edge, will be reviewed. Also, theoretical models, explaining the detachment conditions, low-frequency oscillations at the detachment onset, and mechanisms of the detached plasma stabilization by RMP, will be discussed.

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“…The electron density at the core boundary at R = 2.895 m and the heating power are fixed to 5 × 10 19 /m 3 and 10 MW, respectively. Details of the grid system and the modeling parameters are found in papers [6,7].…”

Section: Modeling Of a Liquid Metal Limitermentioning

confidence: 99%

Application of EMC3-EIRENE to Estimation of Influence of a Liquid Metal Limiter on an LHD-Type Fusion Plasma

Kawamura

Miyazawa

Goto

et al. 2018

Plasma and Fusion Research

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Recently, a new limiter concept with liquid metal for a helical fusion reactor was proposed. This work present a modeling study to understand the influence of the limiter to the plasma and to find critical parameters for the liquid limiter concept. EMC3-EIRENE code is applied to a limiter configuration of a vertical column formed with plane surfaces at the inboard side of the Large Helical Device (LHD). The calculation results indicate that heat load on the helical divertor plates is significantly reduced when the limiter is inserted into the ergodic layer even without impurities. However, the influence of impurity radiation is too large in some cases. In order to achieve a large reduction of divertor flux and to avoid a large reduction of core electron temperature, parameter scans with limiter position and sputtering yield were performed. The results suggest that the limiter position is a critical parameter for acceptable degradation of the core and sufficient reduction of divertor flux.

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Three-dimensional impurity transport modeling of neon-seeded and nitrogen-seeded LHD plasmas

Cited by 42 publications

References 34 publications

Divertor Detachment with Multi-Species Impurity Seeding in LHD

Divertor Detachment with Multi-Species Impurity Seeding in LHD

Experimental Studies of and Theoretical Models for Detachment in Helical Fusion Devices

Application of EMC3-EIRENE to Estimation of Influence of a Liquid Metal Limiter on an LHD-Type Fusion Plasma

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