Contrats post-doctoraux

POST-DOCTORAL POSITION : Understanding of the production of atomic steam of pure metal and interactions gas/laser - Process of isotopic separation by laser way

We are now offering a post-doctoral position specializing in the physics of gases, plasma, and matter/laser interactions. He will be responsible for working on the understanding of the production of atomic steam (without/with co-evaporant) near the melting point of the pure metal, as well as on the interactions gas/laser of the process in question. The post-doctorate is responsible for ensuring the palladium evaporation tests with the teams already in place, which are : the control of evaporation, the related measures and the behavior of atoms in the vapor phase, then coupling the lasers coming from the laser part of the process in order to study the gas/laser interactions prior the extraction selection of the isotopes of interest. This extraction will also to be defined and tested. The ultimate goal of this initial program is to produce, on a laboratory scale, a few grams of palladium depleted in 105 Pd (from natural palladium « first fruit » of the final 107 Pd radioactive one).

He will also have to ensure laser spectroscopy measurements in the UV in order to refine the sequences of photons for selective photoionization of the desired isotopes. These data are essential for the project in the understanding of atomic vapor phenomena and matter/laser interaction. To do this, the post-doctorate will participate in the definition, assembly and development of the evaporator, the coupling of the process lasers with the vacuum chamber (ensure the photoionization of atoms in the vapor phase). Team exchanges will be set up on this specific subject with recognized specialists within the CEA/DRF. The diagnostic measurements of the laser quality but also the measurements coming from the gas/laser interactions are to be implement.

Particular attention will be paid to the publications to be produced essentially within the framework of the gas/laser interactions (selective photoionization of the atoms of interest and extraction of the latter).

The post-doctoral contract is based on the project of the AO PIA waste N°4 labeled in T2/22 which is out of 4 years.

Contacts : Dr Pascal LEMAIRE pascal.lemaire@cea.fr

Post-doctorat : Development of prototype lasers from visible to UV devoted to a process of isotopic separation by laser way

Context :

The enrichment process study department (SEPE), based in Pierrelatte, is made up of four laboratories: a technical support laboratory and three research and development laboratories. The LCDC is the Component Characterization Laboratory. These units are located on the site of ORANO/Tricastin (Pierrelatte). The studies carried out in the laboratory relate to several themes concerning the processes of isotopic separation and in particular that by Laser way.

As part of a new project (PRATA) responding to the call for tenders for the Investment and Future Plan of Waste Report No. 4, the laboratory is in charge of developing a new facility. This lab studies an isotopic separation process by laser (Isotopic Separation by Atomic Vapor Laser) of palladium issued from the reprocessing of spent fuel from La Hague. The atomic laser route has been chosen for this project because there is no easily centrifuged palladium compound. Indeed, the products of fission contain elements of the platin-like group, including palladium. The annual quantity produced by reprocessing operations is around two tons per year. This vitrified waste is currently stored on the La Hague site. The cost, demand and scarcity of palladium fully justify interested in recycling this deposit.

A single reprocessing palladium isotope, the 107 radionuclide, artificial beta emitter with a half-life of 6.5 million years, must be removed.

The main objective of the current project is the final demonstration of the feasibility of palladium separation natural (and non-radioactive) in two streams, one enriched and the other depleted in 105Pd (a similar but natural isotope) by means of the process developed and to collect all the data necessary for a next phase of development of a first pilot. The project was labeled by BPI France in the first quarter of 2022.

Description of the research position:

We are now offering a post-doctoral « Ultra Violet laser » specialist position. He will be responsible for the development of prototype lasers from visible to UV devoted to the process. He will participate in the definition, assembly and development of laser test benches. YAG-type pump lasers are pumping existing dye lasers that need to be upgraded. An oscillator and pre-amplifier assembly make it possible to supply a laser beam determined in terms of wavelength, mode, but also temporally and finally spectrally. The passage into the UV is done by frequency doubling with high objectives in terms of performance. This involves a crystal BBO, LBO, KDP or other type of frequency doubler. To do this, the post-doc will participate in the definition of this crystal, but also of the assembly to be deployed and in particular the development of the environment of the crystal doubler. Indeed, it will be necessary to study the crystal by its behavior in front of the incoming photon flux and the expected thermal performance. In addition, the flux resistance of the different materials used will also be a guideline of research. Exchanges will be set up on this specific subjects with world recognized specialists within the DRF CEA unit.

These laser chains will be remotely controlled. Diagnostic tools will also to be develop to carry out the data acquisitions necessary for the operation of the complete chain. The programming (in Python and/or under Labview) of these tools or controls is an essential point of the proposed position.

Particular attention will be paid to the publications to be produced essentially within the framework of the frequency doubling to UV, a complex and widely studied subject worldwide.

The post-doctoral contract is based on the project of the AO PIA waste N°4 labeled in T2/22 which is out of 4 years.

Contacts : Dr Laurent BRUEL laurent.bruel@cea.fr