In order to simulate radiation damage of fusion reactor materials, we have developed an in-situ observation system in 1986, which consisted of an electron microscope of JEM-100C type combined with a 10 keV ion gun and parallel EELS. Using this system, we have observed dynamic processes of structural and chemical changes of materials during ion irradiation. In this paper, we have developed a new in-situ observation system, with which it is possible to observe dynamic process of structural and chemical changes of materials during dual ion beam irradiation.This system consists of an analytical electron microscope of 4000FX type linked with two 40 keV ion beam accelerators, as shown in fig. 1. The maximum possible ion current on the specimen is 50μA/cm2 for 40keV He ion. Ion beams emmitted from duo-plasmatron ion guns are deflected downward by an angle of 30° with selecting magnet and are introduced into the specimen chamber. Ion beams are deflected downward again by an angle of 30° with electrostatic plism and are incident finally at an angle of 60° with the surface of the specimen, as shown in fig. 2. The images of electron microscope during irradiation are recorded with a VTR through a TV camera. It is possible to control the temperature of the specimen during irradiation within the range from 10 K to 1575 K by using both low and high temperature specimen holders. Test of tension for the specimen under irradiation is also possible. The in-situ chemical analysis in the region of 10 nm under irradiation is possible with EDS (UTW type, Tracor Nothern) and parallel EELS (666 type, Gatan). A quadrapole mass spectrometer is attached near specimen chamber to carry out TDS analysis.
Dual Ion Beam Irradiation System for In situ Observation with Electron Microscope.