Ponente
Descripción
The rotating water-cooled tungsten target which is being developed for the second target station (STS) project at Oak Ridge National Laboratory (ORNL) is in its preliminary design phase. The spallation volume of the target consists of tungsten plates which are diffusion bonded to each other with tantalum interlayer. The spallation volume is encapsulated with edge-cooled structural shell made of Inconel 718. The Inconel shell is diffusion bonded to the spallation volume using hot isostatic pressing with a layer of thermal interface material OFHC copper. The lifetime of the target is largely determined by radiation damage characteristics of tungsten, tantalum, Inconel 718 and OFHC copper. While there are materials data and operational records of tungsten, tantalum, and Inconel 718 in spallation environments, the corresponding data of proton and spallation neutron irradiated copper is scares. To study the radiation damage properties of copper in STS beam conditions, which is characterized by a high helium production rate of about 40 appm per year in copper, a low energy proton irradiation campaign followed by helium beam irradiation has been being performed at the Michigan Ion Beam Laboratory. Low energy proton/helium beams below the Coulomb barrier of copper does not activate the sample which enables post irradiation examination (PIE) in a normal lab environment while simulating similar beam conditions to high energy beam on the target in view of He-appm/dpa ratio. The PIE of irradiated copper will be focused on studying helium induced swelling and temperature dependent embrittlement of copper. In this talk, we present an overview of the irradiation campaign program and plan for the PIE. The data will be used to predict the radiation induced swelling rate and loss of ductility in the copper thermal interfacing layer in the STS target, which will help optimizing the target design that can accommodate the identified radiation induced effects. Also, planned future low energy proton beam irradiation campaign for studying selected beam intercepting materials for STS is presented.
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