Optimization Design And Key Technology Research Of EAST Lower Divertor

This paper studies the optimization and upgrading design of EAST(Experimental and Advanced Superconducting Tokamak)lower divertor.The existing lower divertor made of graphite as the first wall material could not meet the test requirements on the strength and thermal load capacity,which would be seriously affects the operation of the experiment.In this paper,according to the actual demand at present,an optimization scheme for the lower divertor is proposed to improve its thermal load capacity and at the same time,it can bear the thermal stress and electromagnetic force of the structure.It does not require significant testing time and cost,nor does it require no changes to existing internal support and water cooling system.According to the structure characteristics of the lower divertor,different designs of the hitting target plate and non-hitting target plate are carried out in this paper.Since the main problem of non-hitting target plate at present is the fragmentation and sputtering of graphite materials,Titanium-Zirconium-Molybdenum(TZM)alloy is used in the optimization design to replace the existing graphite tile.The main problem of hitting target plate is the low heat load capacity,so,it use the tungsten ring(monoblock)replaces the existing structure.An explosive welding technology is used in producing matrix material on the EndBox for the first time,which can weld CuCrZr plate and stainless steel 316L plate tightly together and.It has high structural strength.The upgraded structure can adjust the position of the target plate in the gap of 17mm and has sufficient support strength.Meanwhile,it can also be installed and disassembled in front of the target plate to ensure that the position of the first wall surface of the target plate does not change while using the existing internal support structure.In this paper,an optimization method is proposed for the existing thermal loading method,which is closer to the actual thermal load situation,to ensure tit does not have a high safety factor under the premise of meeting the use requirements,so that more feasible schemes can be adopted in the structural design.It carries out the related thermal analysis and electromagnetic analysis on the optimized design of the structure,and optimizes again through the analysis of the results to ensure the feasibility and reliability of the structure.Finally,the other feasible schemes involved in the structure design of partial filters are discussed,and some of them are studied experimentally.For example,the design scheme of bolt connection with TZM,welding graphite and weld the tungsten copper sheet on the explosive welding substrate.Although these schemes have not been adopted,the relevant data obtained in the experiment have important reference for the later upgrade design of other parts.