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Title: Dust survivability in tokamaks: dust motion in the divertor sheath

 [1];  [1]
  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Technical Report
Country of Publication:
United States
Plasma Physics & Fusion Technology(70); Magnetic Fusion Energy

Citation Formats

Delzanno, Gian Luca, and Tang, Xianzhu. Dust survivability in tokamaks: dust motion in the divertor sheath. United States: N. p., 2013. Web. doi:10.2172/1110312.
Delzanno, Gian Luca, & Tang, Xianzhu. Dust survivability in tokamaks: dust motion in the divertor sheath. United States. doi:10.2172/1110312.
Delzanno, Gian Luca, and Tang, Xianzhu. 2013. "Dust survivability in tokamaks: dust motion in the divertor sheath". United States. doi:10.2172/1110312.
title = {Dust survivability in tokamaks: dust motion in the divertor sheath},
author = {Delzanno, Gian Luca and Tang, Xianzhu},
abstractNote = {},
doi = {10.2172/1110312},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2013,
month =

Technical Report:

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  • The survivability of dust being transported in the magnetized sheath near the divertor plate of a tokamak and its impact on the desired balance of erosion and redeposition for a steady-state reactor are investigated. Two different divertor scenarios are considered. The first is characterized by an energy flux perpendicular to the plate q{sub 0}≃1 MW/m{sup 2} typical of current short-pulse tokamaks. The second has q{sub 0}≃10 MW/m{sup 2} and is relevant to long-pulse machines like ITER or Demonstration Power Plant. It is shown that micrometer dust particles can survive rather easily near the plates of a divertor plasma with q{sub 0}≃1 MW/m{sup 2}more » because thermal radiation provides adequate cooling for the dust particle. On the other hand, the survivability of micrometer dust particles near the divertor plates is drastically reduced when q{sub 0}≃10 MW/m{sup 2}. Micrometer dust particles redeposit their material non-locally, leading to a net poloidal mass migration across the divertor. Smaller particles (with radius ∼0.1 μm) cannot survive near the divertor and redeposit their material locally. Bigger particle (with radius ∼10 μm) can instead survive partially and move outside the divertor strike points, thus causing a net loss of divertor material to dust accumulation inside the chamber and some non-local redeposition. The implications of these results for ITER are discussed.« less
  • Plasma disruptions are an ever present danger to the plasma-facing components in today's tokamak fusion reactors. This threat results from our lack of understanding and limited ability to control this complex phenomenon. In particular, severe energy deposition occurs on the divertor component of the double-null configured tokamak reactor during such disruptions. A hybrid computational model developed to estimate and graphically illustrate global thermal effects of disruptions on the divertor plates is described in detail. The quasi-two-dimensional computer code, TADDPAK (Thermal Analysis Divertor during Disruptions PAcKage), is used to conduct parametric analysis for the TIBER II Tokamak Engineering Test Reactor Design.more » The dependence of these thermal effects on divertor material choice, disruption pulse length, disruption pulse shape, and the characteristic thickness of the plasma scrape-off layer is investigated for this reactor design. Results and conclusions from this analysis are presented. Improvements to this model and issues that require further investigation are discussed. Cursory analysis for ITER (International Thermonuclear Experimental Reactor) is also presented in the appendix. 75 refs., 49 figs., 10 tabs.« less
  • The main accomplishment of this grant was the development of a finite element time dependent magnetofluid code, FEMHD. The code is nonlinear and three dimensional. In the poloidal plane, the elemental cells of the mesh are triangles, which offer both simplicity and adaptability. In the third, toroidal, direction, there is an option of a standard staggered finite difference mesh, or Fourier transforms. The FEMHD code runs on several platforms, including Crays, UNIX workstations, and a parallel version runs on an IBM SP1. Several problems have been considered with the unstructured mesh FEMHD code. They are (1) MHD simulations in divertormore » tokamaks; (2) simulations of ELM-like ballooning modes in divertor tokamaks; and (3) reconnection and singular MHD equilibria.« less
  • The results of model calculations that demonstrate the feasibility of producing the required blister region and a preliminary evaluation of the divertor collection efficiency are presented. (MOW)
  • The bundle divertor, designed for density and impurity control, has been successfully applied on the DITE tokamak. In this application it is subject to high stresses and is restricted to short pulses and low toroidal fields. A new version is made possible by fitting the vacuum vessel close to the toroidal coils. This allows the plasma to exist in the outer regions of higher toroidal field ripple. This ripple bundle divertor should operate at lower stresses and for longer pulses at higher magnetic fields.