Helium and neon enrichment studies in the JET Mark IIAP and Mark IIGB divertors

Groth, M.; Andrew, P.; Fundamenski, W.; Guo, Heng; Hillis, D.L.; Hogan, J.; Horton, L.D.; Matthews, G. F.; Meigs, A.; Morgan, P. D.; Stamp, M.; Stork, D.; Hellermann, M. von

doi:10.1088/0029-5515/42/5/311

Cited by 18 publications

(25 citation statements)

References 20 publications

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“…Integrated modelling of helium transport in the core, edge and pumping plenum using the COCONUT [245], B2-EIRENE [246,247,248], EDGE2D [217], and DIVIMP/NIMBUS [240,249] codes has shown qualitative agreement with experimental observations, which gives some confidence in the modelling predictions for ITER, although further work in this area to refine the predictions is on-going.…”

Section: Helium Exhaust and Noble Gas Impurity Enrichmentmentioning

confidence: 82%

“…Minimizing the gap between the plasma strike zones and the entrance to the pumping plenum enhances ballistic scattering of He neutrals into the pump [239,218,212,240] and minimises the neutral backflow from the pumping plenum into the divertor [233]. Better closure of divertor mechanical leaks enhances compression of deuterium, helium [232,240] and argon [241] but appears to have no effect on helium or argon enrichment. Induced scrapeoff layer flow by the 'puff and pump' technique did not significantly alter the enrichment of helium [242,212,240] but enhanced the neon and argon enrichment in DIII-D [242] and JT-60U [243], although not in ASDEX-U [212] or JET [240].…”

Section: Helium Exhaust and Noble Gas Impurity Enrichmentmentioning

confidence: 99%

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Chapter 4: Power and particle control

Loarte¹,

et al. 2007

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Abstract.Progress, since the ITER Physics Basis publication, in understanding the processes that will determine the properties of the plasma edge and its interaction with material elements in ITER is described. Experimental areas where significant progress has taken place are : energy transport in the SOL in particular of the anomalous transport scaling, particle transport in the SOL that plays a major role in the interaction of diverted plasmas with the main chamber material elements, ELM energy deposition on material elements and the transport mechanism for the ELM energy from the main plasma to the plasma facing components, the physics of plasma detachment and neutral dynamics including the edge density profile structure and the control of plasma particle content and He removal, the erosion of low and high Z materials in fusion devices, their transport to the core plasma and their migration at the plasma edge including the formation of mixed materials, the processes determining the size and location of the retention of tritium in fusion devices and methods to remove it and the processes determining the efficiency of the various fuelling methods as well as their development towards the ITER requirements. This experimental progress has been accompanied by the development of modelling tools for the physical processes at the edge plasma and plasma-materials interaction and the further validation of these models by comparing their predictions with the new experimental results. Progress in the modelling development and validation has been mostly concentrated in the following areas : refinement of the predictions for ITER with plasma edge modelling codes by inclusion of detailed geometrical features of the divertor and the introduction of physical effects, which can play a 2 major role in determining the divertor parameters at the divertor for ITER conditions such as hydrogen radiation transport and neutral-neutral collisions, modelling of the ion orbits at the plasma edge, which can play a role in determining power deposition at the divertor target, models for plasma-materials and plasma dynamics interaction during ELMs and disruptions, models for the transport of impurities at the plasma edge to describe the core contamination by impurities and the migration of eroded materials at the edge plasma and its associated tritium retention and models for the turbulent processes that determine the anomalous transport of energy and particles across the SOL. The implications for the expected performance of the reference regimes in ITER, the operation of the ITER device and the lifetime of the plasma facing materials are discussed. Introduction.This chapter outlines the significant progress achieved since the ITER Physics Basis in understanding basic scrape-off layer (SOL) and divertor processes in a tokamak. The interaction of plasma with first-wall surfaces will have considerable impact on the performance of fusion plasmas, the lifetime of plasma facing components, and the retention of tritium in next step Burning Plasma E...

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Section: Helium Exhaust and Noble Gas Impurity Enrichmentmentioning

confidence: 82%

Section: Helium Exhaust and Noble Gas Impurity Enrichmentmentioning

confidence: 99%

Chapter 4: Power and particle control

Loarte¹,

et al. 2007

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“…The Type I ELMy H-mode is a regime obtained in many divertor tokamaks and has acceptable energy confinement at the high densities required in next step devices and fusion reactors, particularly at higher plasma triangularities [46,22,39,50]. Type I ELMy Hmodes show experimental performances with respect to steady state helium exhaust [52,3,48,11] and divertor power deposition [42,21,45] which could meet the necessary requirements when extrapolated to next step devices such as ITER [23].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of type I ELM energy and particle losses in existing devices and their extrapolation to ITER

Loarte

Saibene

Sartori

et al. 2003

Plasma Phys. Control. Fusion

519

537

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Analysis of Type I ELMs from ongoing experiments shows that ELM energy losses are correlated with the density and temperature of the pedestal plasma before the ELM crash. The Type I ELM plasma energy loss normalized to the pedestal energy is found to correlate across experiments with the collisionality of the pedestal plasma (ν * ped ), decreasing with increasing ν * ped . Other parameters affect the ELM size, such as the edge magnetic shear, etc, which influence the plasma volume affected by the ELMs. ELM particle losses are influenced by this ELM affected volume and are weakly dependent on other pedestal plasma parameters. In JET and DIII-D, under some conditions, ELMs can be observed ('minimum' Type I ELMs with energy losses acceptable for ITER), that do not affect the plasma temperature. The duration of the divertor ELM power pulse is correlated with the typical ion transport time from the pedestal to the divertor target (τ Front || = 2πRq 95 /c s,ped ) and not with the duration of the ELMassociated MHD activity. Similarly, the timescale of ELM particle fluxes is also determined by τ Front ||. The extrapolation of the present experimental results to ITER is summarized.

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“…ELMs allow sustainment of steadystate phases with exhaust of impurities such as helium ash [5][6][7][8]. ELMy H-mode experiments performed in many divertor tokamaks have also demonstrated favorable energy confinement.…”

Section: Introductionmentioning

confidence: 99%

Pedestal Characteristics of H-Mode Plasmas in JT-60U and ASDEX Upgrade

Urano¹,

Kamada²,

Takizuka³

et al. 2005

J. Plasma Fusion Res.

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The role of the pedestal structure in ELMy H-mode plasmas for the core energy confinement and for the ELM energy losses were investigated in two tokamak-type devices, JT-60U and ASDEX Upgrade. The confinement degradation seen at higher densities is attributed to the reduction of the pedestal temperature limited by the ELM activities and the stiffness of the temperature profiles. In high triangularity or impurity seeded H-modes, in which higher energy confinement is generally achieved, a higher pedestal temperature is obtained by improving the edge MHD stability or the density profile peaking, respectively. The upper bound of the ELM energy loss is characterized by the pedestal energy. The ELM energy loss can become smaller at fixed pedestal energy when the pedestal collisionality is raised. Raising the pedestal collisionality also enhances the inter-ELM perpendicular transport loss and reduces the ELM loss power fraction. In ASDEX Upgrade, the continuous pellet injection is shown to effectively mitigate ELM losses while preserving the core confinement quality. In JT-60U, the operation regime of grassy ELM is investigated and shown to achieve highly integrated performance of high energy confinement with small ELMs in the low collisionality regime.

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Helium and neon enrichment studies in the JET Mark IIAP and Mark IIGB divertors

Cited by 18 publications

References 20 publications

Chapter 4: Power and particle control

Chapter 4: Power and particle control

Characteristics of type I ELM energy and particle losses in existing devices and their extrapolation to ITER

Pedestal Characteristics of H-Mode Plasmas in JT-60U and ASDEX Upgrade

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