At CEA Paris-Saclay, a triple beam facility has been installed for simultaneous ballistic damage, gas implantation and/or electronic excitation. Samples can be irradiated in the wide temperature range from liquid nitrogen to 1000°C. Evolution in the ion-irradiated material microstructure and changes in the service properties (mechanical, thermal…) are then characterized by on line Raman spectrometry or post mortem. Simulation can greatly help in validating the transposition of material laws derived from ion irradiations –formation and evolution of defect loops and of cavities, segregation, amorphization– to in-reactor conditions.

Ion beams available

The JANNuS-Saclay facility comprises three electrostatic accelerators (respectively named Épiméthée, Japet and Pandore) connected to a triple beam chamber for single-, dual- and triple beam irradiations. Three other chambers are linked to Épiméthée and Pandore for single beam irradiation and/or Ion Beam Analysis.

The three accelerators offer a wide range of beams and more ions have still to be tested. Four gases and two metals are available on Épiméthée. Pandore produces different H and He isotopes. Japet uses a single solid cathode that can be rapidly changed. Combining these many beams enables a variety of dual beam and triple beam conditions that mark the richness of JANNuS-Saclay.

Ion sources and accelerators

Épiméthée is a 3 MV single-ended electrostatic accelerator (3-UH-2 Pelletron, National Electrostatics Corp.) equipped with an electron cyclotron resonance (ECR) source (Pantechnik, Nanogan type) able to provide highly damaging beams with large energies and ranges, and also gases: hydrogen, oxygen, noble gases. The ECR source produces high charge states of a variety of ion species, which in combination with the 3 MV acceleration potential can produce ion beams with energies as high as 36 MeV. The source is equipped with four bottles for such gases as O2, He, Ar, Kr, Xe, CH4 and two cartridges of volatile organometallic compounds such as ferrocene and W(CO)6 for producing Fe and W ions. 

Japet is a 2 MV Tandem Pelletron (6SDH-2, National Electrostatics Corp.) equipped with an external SNICS-II ion source (negative ions by cesium sputtering) which can deliver electronegative ions such as H, Cl, I, C, Si, V, Cu, Zr, Ag, Au… This system is capable to produce energies of 0.5 to 4.0 MeV for single-charged ions (like H ions), up to 6 MeV for double-charged ions, and correspondingly higher energies for ions of higher charge states (up 16 MeV for Au ions).

Pandore is a 2.5 MV single-ended electrostatic accelerator (7.5SH-2 Pelletron, National Electrostatics Corp.) equipped with a RF source which produces single-charge ions. Six gas bottles are installed in the vessel that allow producing protons, deuterium ions, helium-4 and helium-3 ions. This accelerator is used for implantation as well as for IBA.

Irradiation chambers

In situ Raman spectroscopy

Raman spectroscopy is an efficient technique for studying the evolution of the microstructure of materials under irradiation such as to determine existing phases before and after irradiation, to outline the stress induced by irradiation, to evidence phase transition under irradiation and to monitor the damage build-up. For that purpose, a confocal Raman spectrometer has been installed in the triple beam chamber, which allows characterizing a variety of materials of nuclear interest. On line Raman spectrometry allows to monitor in real time the evolution of the damage induced by single-, dual- or triple beam irradiations.

In situ Raman is performed with frequency-doubled Nd:YAG (532 nm) laser, ex situ analyses with a Renishaw Invia Reflex device equipped with a Leica DM2500 microscope with 5 objectives (x5, x20, x50, x50L and x100) are also available. In addition to the 532 nm laser, He:Ne (633 nm) and DPSS (457 nm) laser sources complete the experimental set up.

Ion Beam Analysis

An experimental vacuum chamber is connected to Pandore for conventional or channeling ion beam analysis methods as Rutherford backscattering spectrometry (RBS), elastic recoil detection analysis (ERDA) and direct observation of nuclear reaction (NRA) can be applied using protons, deuterons, helium ions as incident beams. Ion beam analyses induced by medium and high energy heavy ions, mainly RBS and ERDA, were also implemented in the single beam chamber connected to Epiméthée.

New setup development

High and low temperature chambers