Runaway electrons are generated when the accelerating force of the electric field overcomes the friction force acting on energetic electrons in a plasma. If confined in a toroidal magnetic field, these energetic electrons can be accelerated to highly relativistic velocity even by a moderate toroidal electric field. Runaway electrons are produced in several natural phenomena, but they are easiest to study in laboratory plasmas. During operation, in tokamak-type magnetic confinement fusion devices we drive a toroidal plasma current in the order of several MA. If there is a sudden increase in plasma resistivity, a large fraction of this current can convert to runaway electron current. A relativistic electron beam with several 100 kA of current can cause substantial damage to the device, thus modelling and understanding of runaway electrons is of highest priority.

At the Institute of Nuclear Techniques, we have an experience of more than a decade in runaway electron modelling. Our network of collaborators spans all over Europe, and from 2014 on we are responsible for the development of runaway electron modelling capabilities in the European Transport Simulator (ETS) that is a 1.5 D tokamak transport workflow. Through steps of including more and more sophisticated models, this year we are working on the integration of full-f kinetic solvers that catch most of the relevant physics.

The job of the doctoral student will be first to get acquainted with the physics of runaway electrons and the ITER Modelling and Analysis Suit, that is the framework of the ETS. Then the doctoral student is to take over the integration effort, and investigate the issues of coupling a full-f code into a 1.5 D transport solver. The work then can progress to the physics exploitation of the self-consistent modelling workflow that will be validated and used for both predictive studies and interpretation of present experiments.

This work is to be executed in an intense international collaboration in the framework of the EUROfusion programme. Good command of English language and real team spirit is required on the top of intermediate level programming and good theoretical physics knowledge.

References:

G I Pokol, M Aradi, B Erdos, G Papp, A Hadar, T Jonsson, D Coster, D Kalupin, P Strand, J Ferreira, the EUROfusion-IM Team: Development of the runaway electron modelling capabilities of the European Transport Simulator, 44th European Physical Society Conference on Plasma Physics. 2017. http://ocs.ciemat.es/EPS2017PAP/pdf/P2.178.pdf