Progress in the engineering design of ITER Langmuir probe

Abstract

High heat flux reaching 10 MW/m2 can be foreseen for the ITER (International Thermonuclear Experimental Reactor) divertor, which is also defined as the designed heat flux for ITER Langmuir Probes because the probes are directly attached on the side of divertors. Such high heat flux induces a high temperature environment and consequent high thermal stress, yet there is no dedicated cooling for the probe structure. A new DLP (Divertor Langmuir probe) design which is called “full-tungsten design” has been proposed for this harsh environment. Alumina is used as the electrical insulating material, which is a kind of brittle material and very easy to generate crack, especially when considering its strength would be decreased due to the elevated temperature.To assess compliance with the heat loads, the probe and environment are simulated using software ANSYS by finite element method. The full-tungsten DLP structure shows good thermal and mechanical behaviors under the specified cyclic thermal loads. Transient thermal analysis combined with elasto-plastic analysis has been performed, the thermal analysis result shows the materials temperature is acceptable. Damages due to progressive deformation as well as time-independent fatigue have been assessed according to the structural design criteria SDC-IC (The Structural Design Criteria for ITER In-vessel Components). Damage on alumina layer due to fast fracture has also been assessed based on the maximum tensile stress theory. The analysis results show the design is quite promising.