POST-DOCTORAL POSITION 2015

Responsible CEA:
MH AUMEUNIER
Responsible Aix-Marseille University:
JL. GARDAREIN, F. RIGOLLET
e-mail: marie-helene.aumeunier<στο>cea.fr
téléphone: 04 42 25 48 34
secrétariat: 04 42 25 65 44

Laboratories:
IRFM, Dpt Integration Plasma-Wall / Lab. Conception and operation of PFC
CEA CADARACHE 13108 Saint-Paul-lez-Durance
IUSTI Lab, TCM / Technopôle de Château Gombert 13453 Marseille

Education: Engineer, PhD
Duration: 2 year
Framework: Funding by AMIDEX (Initiative for Excellence, Aix-Marseille University)
The position is under contract with Aix-Marseille University

Subject: Modeling of fully Infrared Imaging System to prepare plasma experience for WEST project

Scientific context:

The objective of controlled fusion is to recover the energy produced by the reactions of fusion and to convert it into consumable energy. One of the main issues raised by nuclear fusion relates to the design and the exploitation of materials of wall able to support high heat flux (up to 10 MW.m-2 in steady state mode). In this context, the experimental reactor of Tore fusion Supra (CEA/Cadarache) is currently being converted to become a full-metal actively cooled machine.
A major goal is to study the behavior of plasma facing components submitted to high heat and particles flux (up to several MW/m2). For this, the Infrared (IR) Thermography is the usual method to measure the surface temperature of components, which may vary between 20°C and 2000°C. Nevertheless, the use of new metallic in-vessel components makes more complicated the IR measurement interpretation. Indeed, IR thermography detects both the thermal radiations emitted directly from the targets and the ones coming from others components and reflected by the targets, which causes major error in the temperature measurement. Moreover for a same surface temperature, the energy emitted and reflected by the objects changes with the thermal radiative properties of materials. To date, there is no simple experimental technique to get reliable temperature measurement in the fully metallic machine. This is a critical issue for operating in the fusion devices as IR misinterpretation can lead to false alarms or a failure to detect real hot spots that endanger the facilities.
To address the IR interpretation issue, the proposed method is organized around a physics-based simulation. The aim is to model and predict accurately the IR measurement including all physical phenomenons involved in the measurement from the thermal source to optical response.

Mission:

In close collaboration with members of CEA/IRFM and IUSTI, the applicant will work on the development of the integrated numerical model applied to the WEST project. The results of this predictive model compared to experimental data of WEST will allow improving our understanding of observed phenomenon and consolidating physics models.

The work of applicant will concern 2 main issues :

• A thermal issue to convert the deposited heat flux (MW/m2) in surface temperature (°C) by taking the thermal properties of materials and the boundary conditions into account. The applicant will be in charge of testing, comparing, and selecting the thermal modeling (analytical method, FEM, etc.) able to predict the first wall temperature T(x,y,z) for a given plasma scenario. This 3d temperature field will be used both as input of photonic modeling and as input of a Power Load Analysis Tools used to prepare the plasma experience.
• An optical/photonic issue to predict the apparent temperature (the one measured by the camera calibrated with a black body) by taking the radiative environment, the optical features of materials (emissivity and reflectivity) and the instrumental response. Based on a Monte Carlo Ray Tracing, the applicant will be in charge of the implementation of the 3d photonic model of WEST device. This will lead to a library of simulated IR images reproducing all the observed targets and this for different plasma scenario. A parameter sensitivity analysis will allow identifying the key parameters and their impact on the measurement accuracy. This virtual library will be used to interpret the real IR images during the experience, for separating the region dominated by the reflected flux and the real hot spot that endangers the machine.

Profile: Heat transfer, Optical Instrumentation, Simulation, Knowledge on 3D CAD Software, Computer Programming

To apply, please send your CV and reference letters with a brief letter describing your strengths in filling this profile via email to Marie-Hélène AUMEUNIER (marie-helene.aumeunier<στο>cea.fr) and Fabrice RIGOLLET (fabrice.rigollet<στο>univ-amu.fr)