PhD contract (M/F) in Physics/Nuclear Fusion

Job Description

Thesis Subject

Boronization is a well-established technique in tokamak operation, involving the deposition of a thin boron layer on the inner walls of the vacuum chamber. This layer plays a dual role: it acts as a getter for oxygen, reducing the impurity content in the plasma, and it minimizes plasma-wall interactions, thereby reducing both wall erosion and plasma contamination with heavy atoms (such as tungsten). Despite its benefits, several important questions arise concerning the implementation of boronization in ITER, such as hydrogen isotope retention properties of boron layers and erosion rates. Boron films in different tokamak regions are subjected to varying degrees of plasma interaction with different ion energies (from few eV to hundreds of eV) and fluxes, leading to different erosion rates—up to 10 nm/s.
Therefore, we have undertaken preliminary studies on deuterium interaction with a commercially available boron target and found that deuterium is significantly retained in bulk boron materials, with higher release temperatures compared to bulk tungsten. These findings contribute to a better understanding of the role of boron coatings in fusion devices. However, microscopic studies revealed a porous morphology of these targets, not adequately reproducing the thin film deposit found in tokamaks. This might be responsible of a spurious behavior in D/B interaction. To circumvent this issue, the PhD candidate will fabricate B films on W and WOx substrates using a recently purchase electron-beam evaporator. Such source will allow to produce films with controlled thicknesses (from a few atomic layers to a few hundred nanometers) and morphologies—where the few-atomic-layer regime is particularly relevant to borophene-related structures and broader nanoscience applications. These coatings will then be exposed to deuterium ions (250 eV) and plasmas (few eV). To ensure accuracy, all experiments will be performed under vacuum or ultra-high vacuum conditions, avoiding any air exposure prior to ions or plasma. A series of surface science and plasma techniques, including X-ray Photoelectron Spectroscopy (XPS), in-situ Spectroscopic Ellipsometry, gas-phase emission spectroscopy and Langmuir probes, coupled with ex situ analysis (SEM, TEM), will be employed to obtain a comprehensive understanding of the physical and chemical properties of the coatings and the plasma. Such an approach and methodology will allow us both to study the fundamental mechanisms of erosion and to characterize the possible formation of boron-bearing species in the plasma.

Your Work Environment

The Laboratory of Physics of Ionic and Molecular Interactions (PIIM) is a Joint Research Unit (UMR 7345) overseen by Aix-Marseille University and the CNRS (primarily affiliated with the CNRS Engineering and CNRS Physics institutes, and secondarily with the CNRS Chemistry and CNRS Earth & Universe institutes).
The laboratory is recognised for its research activities in the following areas:
• Plasma physics and fusion, particularly via magnetic confinement, in close association with the ITER project;
• Astrochemistry and exobiology, to simulate various environments and to prepare for future space missions and observations;
• Surface sciences and innovative materials;
• Radiation-matter interaction.
The unit is organised into seven research teams and three support teams (technical, scientific computing and IT resources, and administrative and financial). The laboratory has a staff of around 120, including 66 permanent staff. It has a strong experimental component, with numerous prototype set-ups supported by both
standard equipment and high-tech instrumentation.

The successful candidate will be assigned to the Plasma-Surface team. He/she must therefore submit an application to the “Physics and Materials Science” doctoral school (ED352) in order to enrol on a PhD programme at Aix-Marseille University, where she will be granted student status.

Constraints and risks

Experimental subject
Laser, gas, ultra-high vacuum and chemical hazards.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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