Highlights

In-situ Observation of Dynamical Behavior of Helium Bubbles and Dislocation Loops Induced by Irradiation with High-Energy Self-Ions

Scientific Achievement

We have revealed thermal Brownian type motion of helium bubbles statistically and their dynamical response to irradiation with high energy self-ions at high temperature in Al, Cu and Au.  At low temperatures where thermal Brownian type motion does not take place, sporadic and instant displacement of helium bubbles is induced under the irradiation with high energy self-ions in Cu, Au and Fe-9Cr ferritic alloy.  This short range displacement demonstrates thermal spike effects of the cascade.

We have also succeeded to reveal 1-dimensional motion of dislocation loops which was developed from cascade damages under the irradiation with high energy self-ions in Cu at 50K.

This work was able to be performed only by using the facility at EMC, Argonne National Laboratory, which is unique in the world.

Significance

Information about dynamical behavior of helium bubbles and dislocation loops under the cascade damage condition in materials is very important for the development of fusion reactor materials and related basic research.  We cannot directly observe dynamical response phenomena to irradiation with high-energy neutrons, therefore, obtained data using high-energy self-ions instead of neutrons at IVEM-Tandem Facility is trailblazing and seminal.  Our recent work has been reviewed in Materia Japan 45, 106 (2006), published in Nucl. Inst. Meth. Phys Res. B242, 455 (2006), and J. Nucl. Mater. 367-370, 350 (2007) or will be published in J. Nucl. Mater. and Phil. Mag. (available on line).  An invited talk was given at Symposium of Japan Electron Microscopy Society in 2007.  In near future, our study by in-situ observation will be developed in Fe-9Cr or Fe-9Cr-2W which is the first candidate structural material for ITER.

Performers