Design And Analysis Of Helium Tube For Large Nuclear Fusion Superconducting Magnet Coil

The development trend and trend of nuclear power is to build and develop nuclear fusion experimental reactors.The superconducting magnet coil is essential in the large scientific device of nuclear fusion.The superconducting magnet coil provides a strong and stable magnetic field to restrain the plasma and make its motion state meet the requirements.Because of the particularity of superconducting magnet material,it needs to work at very low temperature.In the actual working environment,the superconducting magnet will be affected by the heat of the surrounding environment.In order to keep the temperature of the superconducting magnet in a safe range,it is necessary to continuously cool the superconducting magnet in operation.Coolant is through helium tube into and flow through the surface of the magnet and cooling the magnet.Based on the purpose of cooling magnet,this paper explores the reasonable structure and suitable layout of helium tube,and analyzes and verifies it.The main contents of this paper are summarized as follows;This paper first introduces the development of energy,the development and application of nuclear fusion,the history and development of Tokamak device,the ITER plan and the main structure of ITER device.Secondly,this paper introduces the size and structure of a superconducting magnet coil designed by itself with reference to the coil specifications of the large scientific device.The research status of helium tube is introduced.(2)According to the mechanical engineering criteria and requirements of various aspects,the selection criteria and stress judgment criteria of materials are introduced,and the design of helium pipes is described in detail with reference to flow resistance calculation and design requirements.The structure of helium tube adopts three-stage design,that is,round pipe section,transition section,runway section.The design of variable section can reduce the flow resistance well.(3)Using CATIA modeling,By modifying the structural parameters,Structure models of different sizes,Three pressure loads on the inner wall of MPa pipe are applied to the ANSYS statics simulation module,The change trend of stress and deformation with modified structural parameters is obtained.Comparing the variation trend of stress and strain with the circulation area,Determine that the rounded rectangle length of 12 mm structure more in line with the requirements.Under allowable stress,Analysis shows that the helium tube can withstand about 6 MPa of pressure load.And the fatigue analysis of helium tube under 3 MPa pressure,The results show that the helium tube can withstand at least 95316 shocks.A low temperature fatigue analysis of the helium tube at 77 K,The results show that the helium tube can withstand at least 65220 shocks.(4)With reference to the large scientific apparatus that existed before,combined with the structural size of the coil,heating conditions,cooling capacity of liquid helium,flow rate,pressure and other factors,it is determined that the layout of the helium tube on the whole coil is four in and five out,and the pressure drop between inlet and outlet can be calculated by using the pressure drop formula MPa,which is about 0.06.(5)In the ANSYS Fluent,the whole model of the magnet helium tube is simplified.In order to facilitate the analysis,the boundary conditions such as the heating power of the magnet in the tube are defined and the fluid analysis is carried out.The results show that the temperature rise of helium tube in 1 m is about 0.01 under the condition of flow rate of 1.8 g/s K,then the temperature rise between inlet and outlet is about 0.688.(6)Manufacture of actual helium tube samples and fatigue tests at low temperatures using experimental equipment.Fatigue test results show that the fatigue life at 77 K low temperature is at least 60000 times.The fatigue test was compared with the previous fatigue analysis.