Event-driven PIC-MCC simulations for NBI sources: a proof of concept (plasma strand project)

Supervisor/s – Mohammad Hasan (University of Liverpool)

Neutral beam injection (NBI) is one of the main heating methods planned for use to heat plasma in fusion reactors [1]. Typically NBI is generated by passing a high energy beam of negative ions in a neutraliser. To operate fusion reactors at high gain factors it is desired to maximise the wall efficiency of the NBI system, which is currently 28% for ELISE, the NBI system for ITER [2]. Due to the high power inputs, and the complex electric and magnetic field topologies, experimental optimisation of the design of the negative ions sources for NBI is very expensive and time consuming. As a result, Particle-in-Cell (PIC) codes are used to gain insight into the operation of the negative ion sources and neutralisers, in addition to providing a cheap tool to optimise the design to improve its efficiency.

Multiple PIC codes exist for modelling negative ion sources for NBI, these include Keio-BFX, Bari Ex, and ONIX [3]. A common feature in all these codes is the implementation of simplifying assumptions to reduce the computational time and resources required for running the codes, including reducing the plasma density, truncating the computational domain, or using a scaled value of free space permittivity [3]. These simplifications while reducing the computational costs of the codes limit their ability to investigate larger parameters space.

The aim of this project is to build a proof of concept PIC-MCC code that utilises Discrete Event Simulation (DES) instead of conventional time integration method. The DES is a process modelling technique primarily used in healthcare, supply chain management, and computer networks [4]. Preliminary tests of using this approach showed that a collisionless PIC can be accelerated by up to a factor of 100 [5]. This project will extend this performance to collisional PIC (PIC-MCC) needed for modelling negative ions sources. The code will be applied to a small size negative ions source to benchmark its performance.

The candidate working on this project will be trained in scientific computing covering techniques from plasma physics to industrial engineering, in addition to advanced programming, scientific writing, and presentation skills.

References:

[1] https://www.iter.org/newsline/-/3237
[2] U. Fantz et al, Fusion Engineering and Design 136 part A, 340 (2018)
[3] D. Wunderlic et al, Review of scientific instruments 89, 052001 (2018)
[4] O. Ullrich and D. L├╝ckerath SNE 27(1), 9 (2017) DOI: 10.11128/sne.27.on.10362 [5] H. Karimabadi et al, Journal of Computational Physics 205, 755 (2005)

The project will be mainly based in Liverpool, but there is the opportunity for travel to collaborate with other groups, in addition to international conferences.

This project is offered by The University of Liverpool. For further information please contact: Mohammad Hasan (mihasan@liverpool.ac.uk)

This project may be compatible with part time study, please contact the project supervisors if you are interested in exploring this

Image above: Supervisor/s – Mohammad Hasan (University of Liverpool)