Power requirement for accessing the H-mode in ITER

Martin, Yves; Takizuka, T.

doi:10.1088/1742-6596/123/1/012033

Cited by 432 publications

(649 citation statements)

References 24 publications

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“…This very narrow (5%) power range contrasts strongly with the much wider range, more than a factor of two, seen at 5.6 T. It is closer to that observed on DIII-D and AUG. Figure 17 shows normalized power P loss / e n S vs B T . As for [36]. The upper bound of I-mode powers increases strongly with B T ; we note that many of the discharges at > 5 T are limited by available heating power and that the upper line does not necessarily reflect an I-H threshold.…”

Section: Power Thresholds For L-i and I-h Transitionsmentioning

confidence: 78%

Multi-device studies of pedestal physics and confinement in the I-mode regime

et al. 2016

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Section: Power Thresholds For L-i and I-h Transitionsmentioning

confidence: 78%

Multi-device studies of pedestal physics and confinement in the I-mode regime

et al. 2016

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“…6a show that there is a B dependence as well). The ratio of measured L-I and I-H threshold power to the widely used H-mode threshold power scaling P LH,scaling [29] is shown in Fig. 6b.…”

Section: Access To I-mode and H-modementioning

confidence: 99%

I-mode: an H-mode energy confinement regime with L-mode particle transport in Alcator C-Mod

Whyte

Hubbard

Hughes³

et al. 2010

Nucl. Fusion

290

370

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An improved energy confinement regime, I-mode is studied in Alcator C-Mod, a compact high-field divertor tokamak using Ion Cyclotron Range of Frequencies (ICRF) auxiliary heating. I-mode features an edge energy transport barrier without an accompanying particle barrier, leading to several performance benefits. H-mode energy confinement is obtained without core impurity accumulation, resulting in reduced impurity radiation with a high-Z metal wall and ICRF heating. I-mode has a stationary temperature pedestal with Edge Localized Modes (ELMs) typically absent, while plasma density is controlled using divertor cryopumping. I-mode is a confinement regime that appears distinct from both L-mode and H-mode, combining the most favorable elements of both. The I-mode regime is obtained predominately with ion ∇B drift away from the active X-point. The transition from L-mode to I-mode is primarily identified by the formation of a high temperature edge pedestal, while the edge density profile remains nearly identical to Lmode. Laser blowoff injection shows that I-mode core impurity confinement times are nearly identical with those in L-mode, despite the enhanced energy confinement. In addition a weakly coherent edge MHD mode is apparent at high frequency ~ 100-300 kHz which appears to increase particle transport in the edge. The I-mode regime has been obtained over a wide parameter space (B=3-6 T, I p =0.7-1.3 MA, q 95 =2.5-5). In general the I-mode exhibits the strongest edge T pedestal and normalized energy confinement (H 98 >1) at low q 95 (<3.5) and high heating power (P heat > 4 MW). I-mode significantly expands the operational space of ELM-free, stationary pedestals in C-Mod to T ped~1 keV and low collisionality ν* ped~0 .1, as compared to EDA H-mode with T ped < 0.6 keV, ν* ped >1. The I-mode global energy confinement has a relatively weak degradation with heating power; W th ~ I p P heat 0.7 leading to increasing H 98 with heating power.2

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“…S 0.94 (MW), where n e is the central line-averaged electron density in 10 20 m −3 , B T is the magnetic field in T, and S is the plasma surface area in m 2 [4]. However, ongoing research from many devices found that other 'hidden variables' affect the L-H power threshold.…”

Section: 80mentioning

confidence: 99%

Study on the L–H transition power threshold with RF heating and lithium-wall coating on EAST

Chen

Nielsen

et al. 2016

Nucl. Fusion

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The power threshold for low (L) to high (H) confinement mode transition achieved by radio-frequency (RF) heating and lithium-wall coating is investigated experimentally on EAST for two sets of walls: an all carbon wall (C) and molybdenum chamber and a carbon divertor (Mo/C). For both sets of walls, a minimum power threshold P thr of ~0.6 MW was found when the EAST operates in a double null (DN) divertor configuration with intensive lithium-wall coating. When operating in upper single null (USN) or lower single null (LSN), the power threshold depends on the ion ∇B drift direction. The low density dependence of the L-H power threshold, namely an increase below a minimum density, was identified in the Mo/C wall for the first time. For the C wall only the single-step L-H transition with limited injection power is observed whereas also the so-called dithering L-H transition is observed in the Mo/C wall. The dithering behaves distinctively in a USN, DN and LSN configuration, suggesting the divertor pumping capability is an important ingredient in this transition since the internal cryopump is located underneath the lower divertor. Depending on the chosen divertor configuration, the power across the separatrix P loss increases with neutral density near the lower X-point in EAST with the Mo/C wall, consistent with previous results in the C wall (Xu et al 2011 Nucl. Fusion 51 072001). These findings suggest that the edge neutral density, the ion ∇B drift as well as the divertor pumping capability play important roles in the L-H power threshold and transition behaviour.

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Power requirement for accessing the H-mode in ITER

Cited by 432 publications

References 24 publications

Multi-device studies of pedestal physics and confinement in the I-mode regime

Multi-device studies of pedestal physics and confinement in the I-mode regime

I-mode: an H-mode energy confinement regime with L-mode particle transport in Alcator C-Mod

Study on the L–H transition power threshold with RF heating and lithium-wall coating on EAST

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