METHT KRATOS

The EM7 Very High Voltage Electron Microscope (METHT) located at the CEA centre in Saclay has been in operation since 1981. In 2008-2010, an upgrade was carried out to ensure reliable operation in the years to come. This microscope operates from 0.3 to 1.2 MeV and can form isolated defects (Frenkel pairs) in almost all nuclear metals (steels, Zr alloys). This damage is well known and allows direct comparison of experiments with simulations. Damage rates between 5.10-5 dpa / s and 5.10-3 dpa / s (in metals) can be achieved. With its new Gatan CCD video camera, the transmission electron microscope allows in-situ monitoring. To avoid oxidation of the samples, a very good vacuum is maintained (~ 5 10-8 Torr). Like the other facilities, the parameters of the EM7 microscope (flux, temperature, dose) can be changed easily, allowing parametric studies without any sample activation. The samples that can be irradiated in the microscope are mostly conventional MET thin sections, 3 mm in diameter. Recently, a new single tilt heated sample holder, dedicated to atomic probe tips, has been designed and manufactured. The microscope has been mainly used so far as a tool to study irradiation effects in materials (metallic alloys, ceramics, glasses), especially those of interest for nuclear applications.

• Mr Olivier TISSOT
• Mr Thierry VANDENBERGHE