Physics design of new lower tungsten divertor for long-pulse high-power operations in EAST
-
Published:2021-11-24
Issue:12
Volume:61
Page:126070
-
ISSN:0029-5515
-
Container-title:Nuclear Fusion
-
language:
-
Short-container-title:Nucl. Fusion
Author:
Xu G.S.ORCID, Wang L.ORCID, Yao D.M., Jia G.Z.ORCID, Sang C.F.ORCID, Liu X.J., Chen Y.P., Si H., Yang Z.S., Guo H.Y., Du H.L., Luo Z.P.ORCID, Li H., Zhou Z.B., Cao L., Xu H.C., Xu T.J., Wang Z.L., Zi P.F., Li L., Han L., Xu J.C.ORCID, Liu J.B., Li K.D.ORCID, Cao B., Yu Y.W., Ding F., Ding R.ORCID, Yan N.ORCID, Meng L.Y.ORCID, Tao Y.Q.ORCID, Wang H.Q.ORCID, Zhang Y.ORCID, Shao L.M.ORCID, Zhang X.D., Zhu S.Z., Wan B.N., EAST Team the
Abstract
Abstract
A new lower tungsten divertor has been developed and installed in the EAST superconducting tokamak to replace the previous graphite divertor with power handling capability increasing from <2 MW m−2 to ∼10 MW m−2, aiming at achieving long-pulse H-mode operations in a full metal wall environment with the steady-state divertor heat flux of ∼10 MW m−2. A new divertor concept, ‘corner slot’ (CS) divertor, has been employed. By using the ‘corner effect’, a strongly dissipative divertor with the local buildup of high neutral pressure near the corner can be achieved, so that stable detachment can be maintained across the entire outer target plate with a relatively lower impurity seeding rate, at a separatrix density compatible with advanced steady-state core scenarios. These are essential for achieving efficient current drive with low-hybrid waves, a low core impurity concentration and thus a low loop voltage for fully non-inductive long-pulse operations. Compared with the highly closed small-angle-slot divertor in DIII-D, the new divertor in EAST exhibits the following merits: (1) a much simpler geometry with integral cassette body structure, combining vertical and horizontal target plates, which are more suitable for actively water-cooled W/Cu plasma facing components, facilitating installation precision control for minimizing surface misalignment, achieving high engineering reliability and lowering the capital cost as well; (2) it has much greater flexibility in magnetic configurations, allowing for the position of the outer strike point on either vertical or horizontal target plates to accommodate a relatively wide triangularity range, δ
l = 0.4–0.6, thus enabling to explore various advanced scenarios. A water-cooled copper in-vessel coil has been installed under the dome. Five supersonic molecular beam injection systems have been mounted in the divertor to achieve faster and more precise feedback control of the gas injection rate. Furthermore, this new divertor allows for double null divertor operation and slowly sweeping the outer strike point across the horizontal and vertical target plates to spread the heat flux for long-pulse operations. Preliminary experimental results demonstrate the ‘corner effect’ and are in good agreement with simulations using SOLPS-ITER code including drifts. The EAST new divertor provides a test-bed for the closed divertor concept to achieve steady-state detachment operation at high power. Next step, a more closed divertor, ‘sharp-cornered slot’ divertor, building upon the current CS divertor concept, has been proposed as a candidate for the EAST upper divertor upgrade.
Funder
National Magnetic Confinement Fusion Program of China National Natural Science Foundation of China
Subject
Condensed Matter Physics,Nuclear and High Energy Physics
Cited by
42 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|