Combined heating experiments in ELM-free H modes in JET

Rimini, F.; Andrew, P.; Balet, B.; Bull, J.; Deliyanakis, N.; Esch, H.P.L. de; Eriksson, L.‐G.; Gormezano, C.; Gowers, C.; Guo, Heng; Huysmans, G. T. A.; Jones, T. T. C.; König, R.; Lennholm, M.; Lomas, P.; Maas, A.; Mantsinen, M.; Marcus, F.B.; Nave, M. F. F.; Parail, V.; Start, D.F.H.; Taroni, A.; Testa, D.; Thomas, Paul R.

doi:10.1088/0029-5515/39/11/310

Cited by 24 publications

(15 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For more than 30 years, this method has been used to produce high performance plasmas in a wide range of laboratory fusion devices [1]. The culmination of these studies was the demonstration of efficient ICRF heating of deuterium-tritium plasmas in the TFTR and JET tokamaks in the late 1990s [145][146][147]. More recent studies [148][149][150][151] have confirmed the physics basis for ICRF-based scenarios in a wide range of plasma operational regimes that simulate those anticipated in ITER.…”

Section: Heating and Current Drive Using Ion Cyclotron Waves 451mentioning

confidence: 99%

Chapter 6: Steady state operation

Gormezano¹,

et al. 2007

Self Cite

View full text Add to dashboard Cite

Significant progress has been made in the area of advanced modes of operation that are candidates for achieving steady state conditions in a fusion reactor. The corresponding parameters, domain of operation, scenarios and integration issues of advanced scenarios are discussed in this chapter. A review of the presently developed scenarios, including discussions on operational space, is given. Significant progress has been made in the domain of heating and current drive in recent years, especially in the domain of off-axis current drive, which is essential for the achievement of the required current profile. The actuators for heating and current drive that are necessary to produce and control the advanced tokamak discharges are discussed, including modelling and predictions for ITER. The specific control issues for steady state operation are discussed, including the already existing experimental results as well as the various strategies and needs (qψ profile control and temperature gradients). Achievable parameters for the ITER steady state and hybrid scenarios with foreseen heating and current drive systems are discussed using modelling including actuators, allowing an assessment of achievable current profiles. Finally, a summary is given in the last section including outstanding issues and recommendations for further research and development.

show abstract

Section: Heating and Current Drive Using Ion Cyclotron Waves 451mentioning

confidence: 99%

Chapter 6: Steady state operation

Gormezano¹,

et al. 2007

Self Cite

View full text Add to dashboard Cite

show abstract

“…[1] are included together with their corresponding DD references. In addition, the following DD experiments are included: plasma current scans [25], performance optimization scans with both neutral beam only and combined neutral beam and ICRF [32], power step down experiments [27] …”

Section: Comparisons Of Data With Model Predictionsmentioning

confidence: 99%

Edge transport barrier in JET hot ion H modes

Guo¹,

Lomas²,

Parail³

et al. 2000

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

Abstract. The effects of changing beam and plasma species on the edge transport barrier are investigated for ELM-free hot ion H mode discharges from the recent DT experiments on JET. The measured pressure at the top of the pedestal is higher for mixed deuterium and tritium and pure tritium plasmas over and above the level measured in pure deuterium plasmas at the same heating power. The pedestal pressure increases with beam tritium concentration for mixed deuterium-tritium beam injection into deuterium plasmas where the measured edge tritium concentration remains low. Alpha heating plays a significant role in the core of such plasmas, and the possible impact on the edge is discussed together with possible direct isotopic effects. Heuristic models for the transport barrier width are proposed, and used to explore a wider range of edge measurements including full power DD and DT pulses. This analysis supports the plasma current and mass dependence for a barrier width set by the orbit loss of either thermal or fast ions, though it does not unambiguously distinguish between them. The fast ion hypothesis could well account for some of the JET observations, though more theoretical work and direct experimental measurement would be required to confirm this. An ad hoc model for the power loss through the separatrix, P loss ∝ n 2 edge Z eff ,edge I −1 p , is proposed based on neoclassical theory, a ballooning limit to the edge gradient and a barrier width set by the poloidal ion gyroradius. Such a model is compared with experimental data from JET. In particular, the model ascribes the systematic difference in loss power between the Mark I and Mark II divertors to the change in the measured Z eff . This change in Z eff is consistent with the observed change in impurity production, which is described in some detail, together with a possible explanation provided by the temperature dependence of chemical sputtering.

show abstract

“…In the EAST superconducting tokomak [33,34], a longpulse (>15 s) ELM-absent H-mode was achieved recently for the first time with 4.6 GHz LHCD heating and a lithium wall coating. (Here the ELM-absent H-mode is different from the previous ELM-free H-mode, with lower impurity accumulation and core radiation [23][24][25][26].) These ELM-absent H-mode discharges are usually accompanied by an electrostatic edge coherent mode (ECM), as detected by several edge fluctuation diagnostics such as HeBES (helium beam emission spectroscopy), RPL-probe (reciprocating Langmuir probe [35]), GPI (gas puff imaging [36]) and refl.…”

Section: Introductionmentioning

confidence: 98%

“…by resonant magnetic perturbations (RMPs) [6][7][8][9][10], pellet or supersonic molecular beam injection (SMBI) [11][12][13], imposed vertical plasma oscillation [14], lower hybrid current drive (LHCD)-induced 3D edge magnetic topology [15], and impurity seeding [16]; (2) the development of spontaneous stable small/no ELM H-mode scenarios. Significant progress has been made in the past decades, achieving a grassy ELM H-mode in JT-60U [17,18], a type-II ELM H-mode in ASDEX-Upgrade and JET [19][20][21], a mossy ELM H-mode in TCV [22], an ELM-free H-mode in ASDEX-Upgrade, JET, NSTX and DIII-D [23][24][25][26], a quiescent H-mode (QH) in DIII-D [27,28], an enhanced D α H-mode (EDA) in Alcator C-Mod [29,30] and a high-recycling steady H-mode (HRS) in JFT-2M [31,32], and so on.…”

Section: Introductionmentioning

confidence: 99%

A stationary long-pulse ELM-absent H-mode regime in EAST

Wan

et al. 2017

Nucl. Fusion

View full text Add to dashboard Cite

A stationary edge-localized mode (ELM)-absent H-mode regime, with an electrostatic edge coherent mode (ECM) which resides in the pedestal region, has been achieved in the EAST tokamak recently. This regime allows the operation of a nearly fully noninductive long pulse (>15 s), exhibiting a relatively high pedestal and good global energy confinement with H 98,y2 near 1.2, and excellent impurity control. Furthermore, this regime is mostly obtained with a 4.6 GHz lower hybrid current drive (LHCD) or counter-current neutral beam injection (NBI), plus electron cyclotron resonance heating, and an extensive lithium wall coating. This stationary ELM-absent H-mode regime transits to a stationary small ELM H-mode regime, and upon additional heating power from the 2.45 GHz LHCD, an ion cyclotron resonant frequency or co-current NBI is applied (under 4.6 GHz LHCD heating background). A slight change of the plasma configuration also makes the small ELMs reappear. The experimental observations suggest that a long-pulse ELM-absent regime can be induced by the ECM, which exhibits strong electrostatic fluctuations and may provide a channel for continuous particle (especially impurities) and heat exhaust across the pedestal. The ECM exists in the collisionality of ν * e = 2.5-4 and the pressure gradient |∇P| = | dP dρ | = 100-200 (kPa), which is in good agreement with the previous simulation of GYRO. This ELM-absent H-mode regime with ECM may offer a suitable candidate for high-performance, steady-state H-mode operation in future fusion reactors.

show abstract

Combined heating experiments in ELM-free H modes in JET

Cited by 24 publications

References 23 publications

Chapter 6: Steady state operation

Chapter 6: Steady state operation

Edge transport barrier in JET hot ion H modes

A stationary long-pulse ELM-absent H-mode regime in EAST

Contact Info

Product

Resources

About