Studying the Physics behind Edge Eruptions in Tokamak Plasmas

Dr David Dickenson, University of York
Small plasma eruptions can play an important role in flushing out impurities and preventing the pressure from building up to values that may trigger more damaging, large magnetohydrodynamic (MHD) eruptions. The mechanisms behind these small eruptions are not well understood. A new theory being explored at York posits that a transition between a weakly unstable system to a strongly unstable one, only possible under certain critical conditions, may explain the intermittent bursts of plasma heat and particle transport observed in several tokamaks. Previous work with a simple physics model has demonstrated that such a transition could indeed be related to these small bursts. Here we employ a more realistic physics-based model to allow a more detailed study and more robust conclusions.

Investigating the impact of collisions and sheared flows on microinstabilities in a novel fusion device

Dr David Dickinson, University of York
Small-scale plasma instabilities, known as microinstabilities, found in magnetically confined plasmas created in tokamaks often limit  fusion performance capabilities. One way to improve performance, and hence the potential for net energy production, is to build larger devices. Not only do these microinstabilities increase costs but make engineering a challenge. An alternative method is to try to optimise the design of the device, at fixed size, so that the microinstabilities are less unstable. In this project, we will use high-performance gyrokinetic simulations to explore the role that collisions and sheared flows may play in stabilising microinstabilities in a proposed compact tokamak design, FNSF.

Advanced Modelling of CERN AWAKE Experiment

Dr Guoxing Xia, University of Manchester

The AWAKE project is an international scientific project which comprises of more than 16 institutions involving over 60 engineers and physicists. AWAKE at CERN is the world’s first proton driven plasma wakefield acceleration experiment. The project will utilise proton beams from the SPS in order to stimulate the strong plasma wakefields, accelerating a handful of electrons to GeV level. Compared to conventional RF-based accelerator technology, this novel plasma acceleration can significantly improve the accelerating gradients, ultimately reducing the cost and footprint of future machines. The project aims to make long-term continuation applicable to more complex experiments.

Magnetic field evolution in a neutron star

Dr Toby Wood, University of Newcastle 

Neutron stars have the strongest magnetic fields in the universe, billions of times stronger than the magnetic fields of the Sun and Earth. The magnetic field strongly affects the dynamics of the star, producing changes in its rotation and radiation that can be detected from thousands of lightyears away. This project will use simulations to study the properties of the intense magnetic field in a neutron star, and how it evolves over the star’s lifetime. This work will help us to understand observations from the most distant objects that can currently be detected.

The purpose of this project is to simulate the dynamics and evolution of the magnetic field in neutron stars. This requires resolving the dynamics over a wide range of length- and time-scales, which makes this a computationally demanding project.

 

Quantum Gas Dynamics

Prof Nikolaos Proukakis, Newcastle University

Systems of trapped atoms at unprecedented low temperatures, (billionths of a degree above absolute zero) now routinely accessible experimentally, enable a unique view of the quantum world. A key phenomenon arising in such systems is that of Bose-Einstein Condensation, which is a universal phenomenon manifesting itself through all different physical scales, from the subatomic to the astrophysical scales. The controllability of ultracold atoms also enables potential applications to quantum technologies, a focus research area within the UK. A key challenge is the accurate description of the dynamical evolution of the gases at finite temperature, especially the dynamical interactions between the coherent and the incoherent components of the gases. In this project, we approach this problem through the numerical implementation of a combination of state-of-the-art kinetic and stochastic models, with emphasis on issues of direct experimental relevance.

Our most immediate focus at present is on the dynamics of the partially-condensed Bose gas (single species or binary mixtures), whose dynamics can be well described by a kinetic model (known as the ‘ZNG’ model), which describes both the coherent and incoherent gas components, being the only model to fully accommodate all collisional couplings between them. Such numerical simulations involve direct simulation Monte Carlo, which is computationally intensive. Related future work is envisaged to take place through a related stochastic model, which can provide critical insight about the phase transition itself.

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