The JANNuS is a multi-ion beam irradiation platform jointly managed by the "Commissariat à l’Energie Atomique" (CEA), the "Centre National de la Recherche Scientifique" (CNRS) and the "Université Paris-Sud 11" (UPS).

CEA is acting through its "Nuclear Energy Division" (DEN/DANS/DMN/SRMP) and the "Institut National des Sciences et Techniques Nucléaires" (INSTN).

CNRS is acting through the "Institut National de Physique Nucléaire et de Physique des Particules" (IN2P3).

UPS, CNRS/IN2P3 are acting through the "Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse" (CSNSM).

JANNuS has been established on two neighbouring sites:

• At CEA Saclay, a triple ion beam facility allows the simultaneous production 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 (YVETTE or ÉPIMÉTHÉE for IBA measurement, ÉPIMÉTHÉE or JAPET for implantation/irradiation), ii) dual beam (ÉPIMÉTHÉE + JAPET or ÉPIMÉTHÉE + YVETTE or JAPET + YVETTE) and iii) triple beam (ÉPIMÉTHÉE + YVETTE + 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 will play an essential role for multi-scale modelling of irradiation effects in materials.