Advanced divertor configurations with large flux expansion

Soukhanovskii, V.; Bell, R. E.; Diallo, A.; Gerhardt, S. P.; Kaye, S. M.; Kolemen, Egemen; LeBlanc, B.; McLean, A.G.; Ménard, J.; Paul, S. F.; Podestà, M.; Raman, R.; Ryutov, D. D.; Scotti, F.; Kaita, R.; Maingi, R.; Mueller, D.; Roquemore, A. L.; Reimerdes, H.; Canal, G. P.; Labit, B.; Vijvers, Waj Wouter; Coda, S.; Duval, B.P.; Morgan, T.W.; Zielinski, JJ Jakub; Temmerman, G. De; Tál, B.

doi:10.1016/j.jnucmat.2013.01.015

Cited by 25 publications

(16 citation statements)

References 34 publications

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“…From the geometrical point of view the increase of the flux expansion causes an increase of the flux tube volume [29] through changes in the the parallel connection length between upstream and the target as well as an increase of the plasma-wetted area. Examples of the configuration variation from smaller to larger flux expansion are shown in Figure 3.…”

Section: Experimental Scenarios: Flux Expansion Scanmentioning

confidence: 99%

Modification of SOL profiles and fluctuations with line-average density and divertor flux expansion in TCV

et al. 2017

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Abstract. A set of Ohmic density ramp experiments addressing the role of parallel connection length in modifying Scrape Off Layer (SOL) properties has been performed on the TCV tokamak. The parallel connection length has been modified by varying the poloidal flux expansion f x . It will be shown that this modification does not influence neither the detachment density threshold, nor the development of a flat Scrape Off Layer (SOL) density profile which instead depends strongly on the increase of the core line average density. The modification of the SOL upstream profile, with the appearance of what is generally called a density shoulder, has been related to the properties of filamentary blobs. Blob size increases with density, without any dependence pn the parallel connection length both in the near and far SOL. The increase of the density decay length, corresponding to a profile flattening, has been related to the variation of the divertor normalized collisionality Λ div [1,2], showing that in TCV the increase of Λ div is not sufficient to guarantee the SOL upstream profile flattening.

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Section: Experimental Scenarios: Flux Expansion Scanmentioning

confidence: 99%

Modification of SOL profiles and fluctuations with line-average density and divertor flux expansion in TCV

et al. 2017

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“…One recent idea for tokamak divertor is using a higher order null (dubbed "snowflake") instead of the standard x-point [1]. Snowflake divertor configuration has a characteristic hexagonal separatrix structure, and it has a number of geometric properties that may affect edge plasma and may be helpful for alleviating the divertor heat flux problem: stronger fanning of the poloidal flux, stronger magnetic shear in the edge region, larger radiating volume, and larger connection length in the scrape-off layer [2].…”

Section: Introductionmentioning

confidence: 99%

“…Theoretical considerations [3,4] and recent experimental observations from snowflake divertor experiments on several tokamaks indicate that presence of a near-second-order null of poloidal field may give rise to strong plasma mixing near the magnetic divertor null point, thereby providing sharing of heat and particle flux between multiple (three to four) strike points [5,2].…”

Section: Introductionmentioning

confidence: 99%

Toroidally symmetric plasma vortex at tokamak divertor null point

Umansky

Ryutov

2016

Physics of Plasmas

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Reduced MHD equations are used for studying toroidally symmetric plasma dynamics near the divertor null point. Numerical solution of these equations exhibits a plasma vortex localized at the null point with the time-evolution defined by interplay of the curvature drive, magnetic restoring force, and dissipation. Convective motion is easier to achieve for a second-order null (snowflake) divertor than for a regular x-point configuration, and the size of the convection zone in a snowflake configuration grows with plasma pressure at the null point. The trends in simulations are consistent with tokamak experiments which indicate the presence of enhanced transport at the null point.

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“…From tokamak experiments and theory [2,18] , it is found that most of is transported to the divertor target plates with a heat load width which will be less than 5mm at the outer mid-plane of HL-2M. The flux surface expansion and connection length of the snowflake divertor are much larger than that of the standard divertor, especially at the point with less than 2mm, and both of these increases are expected to reduce the heat load on the divertor target by broadening the heat load profile [19] . With the same computational boundary plasma conditions as in the standard divertor simulated above, the snowflake-minus divertor shown in figure 6 (b) is simulated by SOLPS5.0.…”

Section: Simulation Resultsmentioning

confidence: 97%

“…For DN tripod divertor configurations, constant cross-field transport factors D = 0.3m 2 /s and χ e = χ i = 1.0m 2 /s are used. When n sep =1.4×10 19 /m 3 and = 10MW, the heat load profiles on the target plates of the three divertor configurations are shown in figure 17. As the heat load profiles on the upper-inner and lower-inner targets depicted in figure 17 (a) and figure 17 (c) show, the peak heat loades are located at the point near the separatrix, but their values are less than 2.0MW/m 2 .…”

Section: Simulation Resultsmentioning

confidence: 99%

Advanced divertor concept design and analysis for HL-2M

Zheng

Ryutov

et al. 2016

Fusion Engineering and Design

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HL-2M is a tokamak device that is under construction and will be put into operation in the near future. Based on the magnetic coil design of HL-2M, standard divertor, snowflake divertor and tripod divertor configurations have been designed. The potential properties of snowflake divertor configurations have been analyzed, such as the low poloidal field () area around the X-point, the connection length, target plate and magnetic field shear. The linear peeling-ballooning (P-B) mode is studied by BOUT++ code for snowflake divertor configurations. According to the divertor configuration properties of HL-2M, asymmetric target plates have been concept designed to be compatible with the intended single null (SN) divertor configurations as well as double null (DN) divertor configurations. The SOLPS5.0 code is used to predict the details of the divertor plasma under the conditions of the divertor configurations noted above without impurities. This result shows that the peak heat load on outer target plate of the advanced divertor is about 40% of that of the standard divertor. But more power will be transported to the inner target plate of advanced divertor, and this will cause a higher peak heat load on the inner target plate. The advanced divertor will also have to work under low plasma recycling conditions with high particle temperature and low density in an open divertor target geometry. When the SN configuration changes to a DN tripod divertor configuration, most of the power exhaust is handled by the outer divertor target plates and the peak heat load on these is about 4.1MW/m 2 (with a power exhaust of 20MW). This range of optimized divertor configurations and target geometry will enable the study of advanced divertor physics and high performance plasmas in HL-2M tokamak.

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Advanced divertor configurations with large flux expansion

Cited by 25 publications

References 34 publications

Modification of SOL profiles and fluctuations with line-average density and divertor flux expansion in TCV

Modification of SOL profiles and fluctuations with line-average density and divertor flux expansion in TCV

Toroidally symmetric plasma vortex at tokamak divertor null point

Advanced divertor concept design and analysis for HL-2M

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