The JANNuS is a multi-ion beam irradiation facility jointly managed by the "Commissariat à l’Energie Atomique" (CEA), the "Centre National de la Recherche Scientifique" (CNRS) and the "Université Paris-Sud" (Univ Paris-Sud).

CEA is acting through its "Nuclear Energy Division" (DEN/DANS/DMN/SRMP).

Univ Paris-Sud and CNRS are acting through the "Centre de Sciences Nucléaires et de Sciences de la Matière" (CSNSM). CNRS is acting through one of his instituts called "Institut National de Physique Nucléaire et de Physique des Particules" (IN2P3).

JANNuS has been established on two neighbouring sites:

• At CEA Saclay, a triple ion beam facility allows the simultaneous emulation by ion beams of nuclear recoil damage and implantation of a large array of ions for well-controlled modelling-oriented experiments. The facility is operating according to three modes: i) single beam (PANDORE or ÉPIMÉTHÉE for IBA measurement, ÉPIMÉTHÉE or JAPET for implantation/irradiation), ii) dual beam (ÉPIMÉTHÉE + JAPET or ÉPIMÉTHÉE + PANDORE or JAPET + PANDORE) and iii) triple beam (ÉPIMÉTHÉE + PANDORE + JAPET).

• At CSNSM Orsay, a 200 kV Transmission Electron Microscope is coupled with two ion accelerators (ARAMIS and IRMA) allows in-situ observation of the material microstructure modifications induced by ion irradiation/implantation. The facility is operating according to three modes: i) TEM + IRMA, ii) TEM + ARAMIS and iii) TEM in dual beam (IRMA + ARAMIS).

JANNuS is designed to supply a large range of ion irradiation and implantation conditions, allowing in-situ Transmission Electron Microscopy (TEM) and ion beam analysis with single, dual or triple beam combinations. Such a facilty has no equivalent in Europe and plays an essential role for multi-scale modelling of irradiation effects in materials.