Internationally mobile PhD students - SRIM 2022

• Title of project: "Advanced neutron and photon flux characterization in the irradiation channels of the CNESTEN's TRIGA Mark II reactor".
• Type of project: Internationally mobile
• Duration: 2 months
• Location: Rabat, Morocco

"As a third-year Ph.D. candidate, I am working on the experimental characterization of the irradiation channels of the CNESTEN1's TRIGA Mark II research reactor located in Rabat, Morocco. This type of reactor is specially designed to effectively implement the various fields of nuclear research such as Neutron Activation Analysis, education and training, Neutron Radiography, Detectors testing and radioisotopes production. During my PhD first year, I developed a complete computational model of the TRIGA reactor using the 3-D continuous energy Monte-Carlo code TRIPOLI4® in order to support planning, design and implementation of new experiments within and beyond the reactor core. Moreover, during my first Ph.D. year, measurements based on neutron activation technique, were carried out in order to characterize the neutron flux in different irradiation channels of the CNESTEN's TRIGA reactor. The latter study was carried out as part of the bilateral collaboration between the French Atomic Energy and Alternative Energies Commission (CEA) and the CNESTEN. This collaboration has been established in order to accurately characterize the irradiation and instrumentation channels of the CNESTEN's TRIGA reactor. Therefore, the work carried out during my thesis should make it possible to extend the experimental validation base of the CNESTEN TRIGA calculation scheme, by proposing, carrying out and analyzing experiments to characterize the neutron and gamma fields at different locations. A critical analysis of this computational model will then be carried out in order to improve its performance with regard to the important parameters during the qualification of nuclear instrumentation.
In January 2022, ISFIN has agreed to finance my mobility project to the CNESTEN. The project as built and presented in the proposal will allow me, on the one hand, to improve and strengthen my scientific and technical skills by carrying out and following up closely new experiments in the reactor (neutron activation technique, ionization chamber measurements and nuclear heating measurements). On the other hand, spending 6 weeks interacting and scientifically exchanging with the nuclear experimental reactor team/community at the CNESTEN will be a great opportunity for me to develop disciplinary and inter-disciplinary skills in the nuclear instrumentation and it will inevitably have an eminent impact, a capital gain and a benefit on my PhD work.

Through this mobility project, I was able to conduct an experimental campaign combining different nuclear measurement methods and techniques that will enable me to strengthen the knowledge of neutron and photon flux within and around the reactor core. Eventually, the characterized irradiation positions will be used, firstly, to validate the computational model of the reactor and, secondly, to both test and calibrate innovative nuclear instrumentations before their implementation in nuclear power plants, and to carry out experiments allowing the improvement of existing knowledge on fundamental parameters in nuclear physics.
I would like to thank the Institut Sciences de la Fusion et de l'Instrumentation en environnements Nucléaires (ISFIN) for funding this mobility project. I would also like to thank the members of the CNESTEN's TRIGA reactor, for providing suitable working conditions and for their valuable technical support to carry on the experiments in the reactor."

• Title of the objective: "Physics informed Neural Network to solve Vlasov-Poisson equation".
• Type of project: Internationally mobile
• Duration: 3 months
• Location: Julich, Germany

• Title of project: "Numerical modelling and validation of migration of tungsten eroded from SAS-VW divertor in DIII-D Tokamak3".
• Type of project: Internationally mobile
• Duration: 2 months
• Location: San Diego, USA

"Through the ISFIN mobility project, a research activity was carried out in collaboration with General Atomics (San Diego, CA, USA). The Goal was to compare the modelling performed with the suite of code SOLEDGE-EIRENE and ERO2.0 with the experimental evidences from DIIID tokamak and the modelling from the code SOLPS-ITER. The focus of the experiments and simulations was the performance of the Small-Angle Slot V-shaped Tungsten coated divertor (SAS-VW divertor). The particular interest in the SAS-VW divertor technology is the possibility of easily reaching the divertor detached regime to control the power and particles exhaust, and hence it is considered very important for engineering purposes. Particular attention was given to the impact of the plasma drifts on the divertor regime. This project gave the opportunity to discover the diversity and the similarity between the European and the US way of researching, as well as the cultural differences. Not least, this project made it possible to visit the natural beauties of California.

Scientific context

My Ph.D. topic is focused on the numerical modelling of W migration from the tokamak walls to through the plasma. As the SAS-VW is coated by Tungsten, this was the occasion for testing simulations models on a machine different from the WEST divertor (object of the main part of my studies). DIIID is a tokamak machine considered to be a very import example of the fusion state of the art. It is also one of the machines with the most powerful diagnostic system, this characteristic makes it very interesting from the point of view of modelling validation.

The project lasted about a month and a half. The first week was dedicated to the data access training and to the modelling preparation. The second and the third week were dedicated to the modelling itself. The fourth week was spent in DIIID control room as preparation for the fifth week in which plasma experiments were followed. In the final week the results of the research activities were collected and presented at the General Atomic weekly meeting. Future projects were also discussed.

Cultural aspects

Long hikes on San Diego beaches, beautiful waves and Californian panoramas characterized this trip. The sunshine and the palms were always there to ease the stress of work, the hard work thought in terms of deliverable, results, and discussions. All together created a good positive mindset to perform research from which I learned an important lesson."