Approach to steady state high performance in DD and DT plasmas with optimized shear in JET

Söldner, F. X.; Baranov, Y.; Bartlett, D.V.; Challis, C.; Chen, H.; Coffey, I.; Cottrell, Geoff; Ekedahl, A.; Gormezano, C.; Greenfield, C. M.; Huysmans, G. T. A.; Lazarus, E. A.; Litaudon, X.; Luce, T. C.; Rice, B. W.; Parail, V.; Rochard, F.; Schild, P.; Sips, A. C. C.; Strait, E. J.; Tubbing, B.J.D.; Hellermann, M. G. von; Wade, M. R.; Ward, D.J.

doi:10.1088/0029-5515/39/3/309

Cited by 52 publications

(26 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[3], the ITB-foot radius often coincides with the q = 2 or 3 surface. A similar result has been also reported from JET [27]. This, however, cannot apply simply to the conditions of the initial formation condition of the ITB in JT-60U, which can occur at an inner region where q < 2 and s < 1, and then the ITB-foot radius expands and is stagnated near the q = 2 surface or s ~ 1.…”

Section: Magnetic Shear Dependence Of the Itb Structuresupporting

confidence: 80%

Profile and Shape Control of the Plasmas with Transport Barriers towards the Sustainment of High Integrated Performance in JT-60U.

Kamada¹

2002

J. Plasma Fusion Res.

View full text Add to dashboard Cite

With the main aim of providing physics basis for ITER and the steady-state tokamak reactor, JT-60U has been optimizing the operational concepts and extending discharge regimes toward the sustainment of high integrated performance. In the two advanced operation regimes, the reversed magnetic shear (RS) and the weak magnetic shear (high-β p ) ELMy H modes characterized by both internal (ITB) and edge (ETB) transport barriers, JT-60U has clarified responses of the transport barrier structure to magnetic shear, heating power, momentum, density, etc. Based on these observations, possible parameter linkages and feedback loops in the core and pedestal regimes have been proposed. With the optimization of profile and shape control, both confinement and high β stability have been enhanced and favorable integrated performance has been achieved. Such operational regimes have been extended to the reactor-relevant regime.

show abstract

Section: Magnetic Shear Dependence Of the Itb Structuresupporting

confidence: 80%

Profile and Shape Control of the Plasmas with Transport Barriers towards the Sustainment of High Integrated Performance in JT-60U.

Kamada¹

2002

J. Plasma Fusion Res.

View full text Add to dashboard Cite

show abstract

“…This year, the combination of a QH mode plasma edge and broad counter-injection ITBs resulted in increased plasma performance. This new, high performance, operating mode with separate (double) core and edge transport barriers is termed the QDB regime (so-called after the [ELMy] JET double barrier (DB) mode [24]). The ELM-free QH mode edge, described in more detail in Refs [22,23], is characterized by continuous multiharmonic MHD activity in the pedestal region.…”

Section: Quiescent Double Barrier (Qdb) Regimementioning

confidence: 99%

Progress towards increased understanding and control of internal transport barriers in DIII-D

et al. 2002

Self Cite

View full text Add to dashboard Cite

Substantial progress has been made towards both understanding and control of internal transport barriers (ITBs) on DIII-D, resulting in the discovery of a new sustained high performance operating mode termed the quiescent double barrier (QDB) regime. The QDB regime combines core transport barriers with a quiescent ELM-free H mode edge (termed QH mode), giving rise to separate (double) core and edge transport barriers. The core and edge barriers are mutually compatible and do not merge, resulting in broad core profiles with an edge pedestal. The QH mode edge is characterized by ELM-free behaviour with continuous multiharmonic MHD activity in the pedestal region and has provided density and radiated power control for longer than 3.5 s (25τ E ) with divertor pumping. QDB plasmas are long pulse high performance candidates, having maintained a β N H 89 product of 7 for five energy confinement times (T i 16 keV, β N 2.9, H 89 2.4, τ E 150 ms, DD neutron rate S n 4 × 10 15 s −1 ). The QDB regime has only been obtained in counter-NBI discharges (injection antiparallel to the plasma current) with divertor pumping. Other results include successful expansion of the ITB radius using (separately) both impurity injection and counter-NBI, and the formation of ITBs in the electron thermal channel using both ECH and strong negative central shear (NCS) at high power. These results are interpreted within a theoretical framework in which turbulence suppression is the key to ITB formation and control, and a decrease in core turbulence is observed in all cases of ITB formation.

show abstract

“…These discharges are characterized by an edge transport barrier (ETB), associated with the enhanced D α (EDA) H -mode, and peaked density profile associated an ITB. 5,6,7 In an EDA H-mode, the particle transport is sufficiently enhanced over the ELM-free (edge localized mode) H-mode level to result in stationary density and impurity levels. 8 Previously, C-Mod ITB experiments have focused upon heating during current ramp-up with ICRF, 9 pellet enhanced performance mode, 10 and the enhanced neutron mode.…”

Section: Introductionmentioning

confidence: 99%

Double transport barrier experiments on Alcator C-Mod

Wukitch¹,

Boivin²,

Bonoli³

et al. 2002

Physics of Plasmas

View full text Add to dashboard Cite

Double transport barrier modes (simultaneous core and edge transport barrier) have been observed with off-axis ion cyclotron range of frequencies (ICRF) heating in the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511]. An internal transport barrier (ITB) is routinely produced in enhanced D α H-mode (EDA) discharges where the minority ion cyclotron resonance layer is at r/a ~ |0.5| during the current flat top phase of the discharge. The density profile becomes peaked without the presence of a particle source in the plasma core and continues to peak until the increased core impurity radiation arrests the improved energy confinement, ultimately leading to a barrier collapse. With the addition of moderate (0.6 MW) central ICRF heating, the double barrier mode was maintained for as long as the ICRF power was applied and modeling shows that the internal thermal barrier was maintained throughout the discharge. The presence of sawteeth throughout most of the ITB discharge allows sawtoothinduced heat pulse analysis to be performed. This analysis indicates that there is an abrupt radial discontinuity in the heat pulse time to peak profile when an ITB is present. Furthermore, this discontinuity appears to move into the core plasma from the edge region in about 0.2 sec, several confinement times. The deduced thermal diffusivity, χ hp , indicates a barrier exists in the electron thermal transport, the barrier is limited to a narrow radial region, and the transport is unaffected outside this narrow radial extent.

show abstract

Approach to steady state high performance in DD and DT plasmas with optimized shear in JET

Cited by 52 publications

References 15 publications

Profile and Shape Control of the Plasmas with Transport Barriers towards the Sustainment of High Integrated Performance in JT-60U.

Profile and Shape Control of the Plasmas with Transport Barriers towards the Sustainment of High Integrated Performance in JT-60U.

Progress towards increased understanding and control of internal transport barriers in DIII-D

Double transport barrier experiments on Alcator C-Mod

Contact Info

Product

Resources

About