Disruption in Tokomak
Plasma-surface Interaction Study in Heat Load Range Typical for Tokamak Disruption and Plasma Technology
Tech Area / Field
- FUS-PLA/Plasma Physics/Fusion
8 Project completed
Senior Project Manager
Karabashev S G
TRINITI, Russia, Moscow reg., Troitsk
- NIIEFA Efremov, Russia, St Petersburg\nVNIITF, Russia, Chelyabinsk reg., Snezhinsk
- Argonne National Laboratory (ANL), USA, IL, Argonne
Project summaryObjectives of Project
The main purpose of proposed project is to investigate the plasma flow-material interaction under conditions of the tokamak disruption and plasma treatment of materials.
Plasma Facing Materials erosion
During the tokamak disruption almost thermal energy of the hot fusion plasma Q > 1 GJ losses for a short time t = 1 ms then the heat flux to the pertor plates achieves a large value S > 100 GW/m2 what results to melting and vaporization. Erosion of the pertor system limits reactor operation and economic reactor lifetime. Even small vapor cloud is enough for absorption of all incoming energy. The vapor plasma is heated up to temperature Т = 5 eV that all absorbed energy is radiated. Afterwhat pertor system and first wall elements interact with this secondary radiation. Erosion of PFM occurs due both vaporization and splashing (for meltable materials). So, for prediction of PFM erosion it is necessary to investigate for real tokamak reactor geometry a) plasma flow energy transfer into radiation and b) interaction of this secondary radiation with candidate materials both nonmeltable (carbon) and meltable (beryllium, tungsten).
Material treatment by plasma flows
Experiments have shown strong improvement of important material properties (hardness, corrosion resistance, hydrogen isotopes permeability) as result of formation of small crystallic and even amorphous structures during recrystalizion after fast heating and cooling of molten surface layers. Experiments in TRINITI (Russia) have shown that such material structure improvement occurs under definite conditions of material treatment by plasma flows and depends on plasma flows parameters, kind of materials and samples geometry. Finding these optimal conditions needs also in investigation of plasma- material interaction but at less powers 5< 10 GW/m2 and time duration т < 0.1 ms.
None of the modelling facilities has all the necessary parameters for full modelling of plasma- surface interaction. Existing theoretical models can not describe all crucial physical phenomena also as its use some phenomenological parameters needed in verification experimentally, especially model for molten metal splashing. Then it is suggested to solve plasma-material interaction by a combination of number of unique facilities in TRINITI (Troitsk, Moscow Reg.) and Efremov Institute (El, St.-Petersburg) by the using not only of plasma guns but the high power CO laser also which allow to study under a wide range of the heat power S = (1-100) GW/m2 , pulse duration t = (0.1- 10) ms and particles energy E = (0.1- 10) keV. Close collaboration with theoretical investigations in TRINITI (Russia) and ANL (USA) makes possible to elaborate adequate model of plasma-surface interaction including vapor plasma dynamics, radiation transport and material structure changing.
The numerical two-dimensional code based on above-mentioned physical model makes possible:
a) to predict the PFM erosion due to vaporization and liquid metal splashing during the tokamak reactor disruptions,
b) to find optimal conditions of material treatment by the accelerated plasma flows.
The foreign participant activities
The foreign collaborator (ANL, USA) participation will has form of discussion of plans of experimental and theoretical investigations conforming with plans of ANL investigations in this field, elaboration of common numerical codes, caring out calculations by the using of ANL computers and discussion of results.
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