In Situ Studies of the Effects of Ion Beams on Materials Using the Electron Microscope Ion Beam Interface

To investigate microstructural evolution by cascade damage produced by energetic heavy particles, we have built a facility which is capable of observing damaged structure introduced by heavy ions in situ in an electron microscope. A 400 kV Cockcroft-Walton type heavy ion accelerator with a Danfysik 911A heavy-ion source has been combined with a 200 kV electron microscope. Heavy ion beams of energies up to 400 keV can bombard the specimen in the microscope with an incident angle of 45 degrees to the electron beam axis. This paper describes the outline of the facility and some of the recent results mainly concerned with heavy radiation damage of materials which are relevant to fast breeder and fusion reactor development. For example, we have investigated microstructural evolution of SUS 316 stainless steel as a function of dose, dose rate and temperature. The topics will also include observation of short-lived clusters of point defects during irradiation in nickel and direct comparison of self-ion damage in aluminum with electron damage caused by an electron beam within the 200 kV microscope. Some of these results have been discussed, compared with cascade simulation and defect kinetics calculations. The experimental results may be useful to establish correlation between neutron and ion damage through microstructural evolution modelling.