Consequences of a reduction of the upstream power SOL width in ITER

Kukushkin, A.S.; Pacher, H.D.; Pacher, G.W.; Kotov, V.; Pitts, R.A.; Reiter, D.

doi:10.1016/j.jnucmat.2013.01.027

Cited by 111 publications

(121 citation statements)

References 9 publications

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“…The latter is uncertain because the applicability of the neoclassical transport formula used to evaluate the bootstrap current in this region is questionable. For the typical values of p ped = 3.0-5.3 kPa obtained from SOLPS simulations for these plasmas with k q = 1.2-3.6 mm [5], these MHD pressure gradient limits correspond to k p = 5.5-8.5 mm at W N = 0.995, similar to the values obtained in a previous analysis following a similar approach [6].…”

Section: Analysis Of Pedestal and Sol Plasma Mhd Stability In Iter Q supporting

confidence: 85%

“…The HD model predicts that a key parameter for the determination of k q is the value of the poloidal field at the magnetic separatrix, yielding k q $ 1-2 mm for 15 MA ITER Q DT = 10 plasmas. These values are typically a factor of 3-4 lower than previously assumed in ITER modelling [5] and lead to parallel heat fluxes in the SOL a factor of 3-4 larger than previously considered. While ITER operation is still found to be feasible in this case (through a combination of increased upstream SOL density and the use of extrinsic impurities to radiatively dissipate power in the divertor [5]), these higher heat fluxes pose additional control challenges during transient phases (re-attachment, confinement transients, etc.…”

Section: Introductionmentioning

confidence: 73%

“…The relation between them [12] can be estimated on the basis of the two point model and depends both on SOL parallel transport (isothermal sheathlimited versus conduction-limited) and on the relation between anomalous particle transport/sources (which determines the SOL density fall-off length k n ) and anomalous heat transport (determining the SOL temperature fall-off length k T ): [5] shows that the plasma density profiles in the ITER SOL are indeed much wider than those of the temperature (k n $ 6k T , giving k q /k p $ 0.33, as expected from Eq. (1.b)) for the range of density considered.…”

Section: Sol Transport In Iter Plasmas and Implications For K Q In Itmentioning

confidence: 99%

See 2 more Smart Citations

MHD stability of the ITER pedestal and SOL plasma and its influence on the heat flux width

Loarte

Liu

Huijsmans

et al. 2015

Journal of Nuclear Materials

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Section: Analysis Of Pedestal and Sol Plasma Mhd Stability In Iter Q supporting

confidence: 85%

Section: Introductionmentioning

confidence: 73%

Section: Sol Transport In Iter Plasmas and Implications For K Q In Itmentioning

confidence: 99%

See 1 more Smart Citation

MHD stability of the ITER pedestal and SOL plasma and its influence on the heat flux width

Loarte

Liu

Huijsmans

et al. 2015

Journal of Nuclear Materials

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“…The use of nitrogen is limited indirectly by MHD effects as β N exceeds the value of 3 in connection with N-induced confinement improvement. Higher values of P sep /R and more pronounced detachment are expected to be achieved with higher divertor neutral pressure, as foreseen for ITER from SOLPS modelling [11]. Some operational challenges appeared in AUG so far, which will not apply to larger devices in this extent.…”

Section: Discussionmentioning

confidence: 97%

Partial detachment of high power discharges in ASDEX Upgrade

et al. 2015

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Abstract. Detachment of high power discharges is obtained in ASDEX Upgrade by simultaneous feedback control of core radiation and divertor radiation or thermoelectric currents by the injection of radiating impurities. So far 2/3 of the ITER normalized heatflux P sep /R= 15 MW/m has been obtained in ASDEX Upgrade under partially detached conditions with a peak target heatflux well below 10 MW/m 2 . When the detachment is further pronounced towards lower peak heatflux at the target, substantial changes in ELM behaviour, density and radiation distribution occur. The time-averaged peak heat flux at both divertor targets can be reduced below 2 MW/m 2 , which offers an attractive DEMO divertor scenario with potential for simpler and cheaper technical solutions. Generally, pronounced detachment leads to a pedestal and core density rise by about 20-40 %, moderate ( 20 %) confinement degradation and a reduction of ELM size. For AUG conditions, some operational challenges occur, like the density cut-off limit for X-2 ECRH heating, which is used for central tungsten control. Partial detachment of high power discharges in ASDEX Upgrade2

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“…The distribution of fluence along the divertor area as measured with probes is plotted in figure 7. The corresponding values of expected fluence in the ITER divertor are provided in [10,11]. Due to the fact that the inner divertor in ASDEX Upgrade is almost always ITR/P5-42 detached yielding to the underestimated fluxes, it was decided to use the data from outer divertors only for this direct comparison.…”

Section: Extrapolation To Iter Conditionsmentioning

confidence: 99%

First studies of ITER-diagnostic mirrors in a tokamak with an all-metal interior: results of the first mirror test in ASDEX Upgrade

et al. 2013

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Abstract.In ITER, mirrors will be used as plasma-viewing elements in all optical and laser diagnostics. In the harsh environment mirror performance will degrade hampering the operation of associated diagnostics. The most adverse effect on mirror performance is caused by the deposition of impurities. It is expected that the most challenging situation will occur in the divertor. With the envisaged changes to all-metal plasma-facing components (PFCs) in ITER, an assessment of mirror performance in an existing divertor tokamak with allmetal PFCs is urgently needed. Molybdenum and copper mirrors were exposed for nearly nine months in ASDEX Upgrade which has alltungsten PFCs. Mirrors were located at the inner wall, under the dome and in the pump-duct. During exposure, the mirrors were heated to temperature in the range 145 o C-165 o C. This was made to approach the expected level of heating due to absorption of neutrons and gammas on mirrors in ITER divertor. After exposure, degradation of the reflectivity was detected on all mirrors. The highest reflectivity drop was measured on mirrors under the dome facing the outer strike point, reaching -55% at 500 nm. The least degradation was detected on mirrors in the pump duct, where the reflectivity was preserved in the range 500-2500 nm and the largest decrease was about -8% at 250 nm. On all contaminated mirrors carbon fraction did not exceed 50 at.% while the major contaminants were metals and oxygen. The degradation of exposed mirrors underlines the necessity for urgent R&D on deposition mitigation and in-situ mirror cleaning in ITER.

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Consequences of a reduction of the upstream power SOL width in ITER

Cited by 111 publications

References 9 publications

MHD stability of the ITER pedestal and SOL plasma and its influence on the heat flux width

MHD stability of the ITER pedestal and SOL plasma and its influence on the heat flux width

Partial detachment of high power discharges in ASDEX Upgrade

First studies of ITER-diagnostic mirrors in a tokamak with an all-metal interior: results of the first mirror test in ASDEX Upgrade

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