Fatigue Analysis Of Tokamak Device For Plasma Facing Components

With the development of fusion research,the parameters of tokamak such as ion temperature,electron temperature and density of particles have been raised.In order to have research on the extremely of the further divertor physics,Southwestern Institute of Physics needs to upgrade the HL-2A tokamak device.The HL-2M tokamak now is under design and construction.The divertor is a vital in-vessel component in tokamak vacuum vessel and faces the plasma directly.In the high-constraint model,it may cause the phenomenon of magnetic fluid instability of the plasma,thus it may cause energy and particles enter the scrape-off layer and move along the magnetic field lines,eventually bombarding the target plane.This energy can reach megawatt level resulting in high temperature rise and high thermal stress at the strike point,and the thermal stress cycle is consistent with the operating cycle of the device,which may cause fatigue damage at different material joints.Therefore,we need to evaluate the thermal fatigue lifetime of the key components of HL-2M divertor.The researchers of Southwestern Institute of Physics have used the SOLPS code to simulate the heat load distribution on the surface of target plane under the snowflake minus divertor configuration.This work follows three aspects of study with finite element program:Firstly,the finite element method was used to simulate the transient heat transfer analysis of the CFC layer and the heat sink layer of the HL-2M divertor under high parameter operation,and the temperature field of different components of the target plate has been calculated out.The thermal properties of the planes had been evaluated.The results show that the temperature of each component was within the limit temperature of the material.Secondly,the temperature field distribution of the target plane had been obtained in previous work,which will be used as the input file of the thermal stress analysis.After that the thermal stress field can be got to evaluate the mechanical properties of the structure.And found that in the area 4 millimeter away from outer pumping port has occurred plastic deformation.Also the axial tensile force and the normal shear force have got,and the bolt stress was calculated by the classical formula.At the same time,thermal stress has simulated in the temperature of 110℃,250℃,and 300℃,and found that the support of cassette structure may have plastic deformation at 300℃.At last,the thermal stress at 300℃ has been simulated again after added the gasket.The stress does not exceed the yield stress of the material.Finally,it analyzes the possibility of ratchet damage occurrence through cyclic stress analysis on the divertor.It will be safe in the cyclic load.And it uses the Structural Design Criteria for ITER In-vessel Components to predict thermal fatigue life of HL-2M divertor.The results show that the fatigue life of the inner and outer target plate as well as dome plane meet the design requirement.