Dr Kate Lancaster, Chair of the Plasma Physics Group at the Institute of Physics, reflects on the UK’s plasma science landscape, discussing innovative projects, applications, and collaborations that position the country as a leader in the field.
The Institute of Physics’ (IOP) Plasma Physics Group functions as an overarching body promoting plasma science and addressing relevant needs within our community. We aim to cover a wide range of expertise within plasma research, from high-power laser-plasma interactions, magnetically confined fusion plasmas, such as tokamaks and stellarators, to space and astrophysical plasmas, encompassing interplanetary and interstellar environments. Furthermore, our scope includes a variety of industrial and biomedical plasmas, which collectively fall under the broader category of technological and non-thermal plasma research.
One of our primary activities is organising an annual conference, bringing together numerous individuals from diverse fields of plasma physics. Researchers often become siloed in their specific areas. This conference fosters crosstalk between different segments of plasma physics and plasma science.
One of our roles at the conference is to offer guidance to the community, addressing any initiatives that may arise. Unlike larger plasma-related conferences, this one maintains a more intimate atmosphere, usually hosting about 100 participants. It provides an excellent opportunity for the members of our community to exchange ideas.
Advancing plasma technologies in the UK
In the field of fusion energy, there are two primary research approaches: inertial confinement fusion and magnetically confined fusion. The UK has world-class laser and pulsed power facilities and significant expertise in inertial fusion, in universities, national labs, and in private fusion companies. However, the strategic, dedicated fusion devices have been largely in the magnetically confined fusion domain.
The UK is developing a fusion project called STEP (led by UK Industrial Fusion Solutions Ltd, a wholly owned subsidiary of the UK Atomic Energy Authority Group), which aims to become operational around 2040, and a suitable site has already been identified at a former power station. STEP plans to utilise a device configuration with a high magnetic field, resembling the shape of a cored apple rather than the traditional doughnut shape tokamak. The UK has a strong history with these so-called ‘high aspect ratio’ tokamak designs, and STEP represents a significant investment in fusion research.
The initial investment in STEP totalled approximately £220m. This was followed by a wider investment in fusion called ‘Fusion Futures’, representing up to £650m, which includes allocations for training and community development, as well as funding for research and development within the UK fusion industry. A recent recommitment to 2025/26 Fusion Futures and additional funding for STEP is on the order of £410m. This shows a huge commitment to making fusion a reality in the UK.
Fusion Futures also funds a major project in inertial fusion called UPLiFT. Led by STFC Rutherford Appleton Laboratory, it comprises academia, industry and other national laboratories and focuses on the UK’s key areas of expertise in lasers, targetry, and high-energy gain fusion.
The UK’s fusion community is highly engaged globally, extending beyond academia to incorporate companies whose primary focus is fusion and fusion technology, alongside a substantial (and growing) supply chain that supports the industry by providing vital infrastructure.
The UK is also making significant progress in space propulsion technologies, especially in plasma thrusters, ion thrusters, and Hall effect thrusters. This development is happening both at universities and in the commercial sector. These technologies offer distinct advantages for deep space exploration, and this type of technology is already employed on satellites for precise trajectory adjustments.
Innovative research in non-thermal plasma is investigating the unique combination of reactive species and UV light to address medical challenges. For example, bacterial biofilms – similar to the plaque that forms on teeth – can hinder wound healing. Non-thermal plasma therapies can potentially disrupt these biofilms, thereby aiding the treatment of chronic wounds.
Interesting chemical processes occur in non-thermal plasmas because atoms present are only partially ionised (process where electrons can escape the atom). The combination of reactive species and UV light creates a unique environment. Consequently, these plasmas have widespread applications in various fields, including sterilisation, treatment, and material functionalisation. Applications also extend to wastewater treatment, the remediation of industrial practices, and serving as catalysts in converting carbon dioxide into alternative chemical species.
A well-established area of application is semiconductor processing, where plasma etching plays a crucial role in fabricating integrated circuits. As chip features continue to shrink, a profound understanding of the behaviour of plasma at the atomic level becomes increasingly essential, requiring new plasma diagnostic techniques.
Space plasma: An integral role in understanding the Universe
About 99.9999% of the visible Universe consists of plasma, found in various forms such as the interstellar medium and stars, with only a small fraction of matter existing in solid, liquid, or gaseous form. Understanding plasma is essential from a fundamental scientific standpoint, contributing to our broader comprehension of the Universe.
The UK has a strong presence in the area of space plasmas, both in academia and national labs. The study of space plasmas is a global effort, especially when considering the requirement for specialised space probes. For example, the European Space Agency’s (ESA) Solar Orbiter and NASA’s Parker Solar Probe are both designed to enhance our understanding of solar wind, magnetic reconnection, and related phenomena. These missions venture into the solar corona, where they perform in-situ measurements of the coronal plasma and capture high-resolution images of the Sun to address fundamental questions, such as why the Sun is so hot and how it appears as it does.
The Parker Solar Probe detected a phenomenon known as ‘switchbacks’ (rapid local flipping of the Sun’s magnetic field), which helps us understand the interaction between the coronal magnetic field and the solar wind. The Solar orbiter revealed that the Sun’s surface is peppered with mini solar flares, often called ‘campfires.’ The coronal environment is highly dynamic, characterised by continuous interactions between magnetic fields and charged particles. The solar wind directly impacts Earth, as extreme solar events can disrupt communications and affect our infrastructure.
Another fascinating area of research involves laboratory astrophysical experiments, often conducted on large laser or pulsed power systems. These experiments allow scientists to create miniature versions of phenomena such as astrophysical jets. Researchers can adjust experimental parameters to establish dimensionless scaling relations that can be extrapolated to astrophysical scales, providing valuable insights into cosmic phenomena and enhancing our understanding of various astrophysical objects. These terrestrial experiments enable researchers to explore concepts that would be challenging to investigate in space due to the associated costs and logistical difficulties.
The National Ignition Facility (NIF) combines laser-driven fusion energy studies with discovery science. Although NIF is not located in the UK, many British scientists are actively involved in research there, contributing to both the fusion mission and to discovery science experiments associated with the facility, particularly in the realm of laboratory astrophysics. This state-of-the-art, laser-driven fusion facility has recently achieved a significant milestone known as ignition, where the energy output exceeds the energy input provided by the lasers. The material has now entered a phase termed ‘burning plasma,’ which mimics some of the conditions found in the sun, essentially creating a miniature star.
Overcoming challenges to achieve real-world applications
Several barriers hinder the practical realisation of fusion energy, both in plasma physics and broader engineering contexts. Plasmas are inherently unstable and influenced by various instabilities. A significant amount of current research in plasma physics focuses on understanding the evolution and growth of these instabilities, as well as developing methods to mitigate them.
In addition to the complexities of plasma physics, substantial engineering challenges must be addressed. One example is the development of materials capable of withstanding extreme temperatures. Within a tokamak, there is an area known as the divertor, analogous to the ‘exhaust pipe’ of the device and must endure conditions akin to landing a small spacecraft on the surface of the sun. Resolving these multifaceted challenges requires ongoing research and innovation in both plasma physics and engineering.
Materials in fusion reactors are subjected to extreme radiation conditions, such as huge neutron yields, which can transmute the reactor wall material, making it radioactive. This phenomenon can also lead to atomic displacement within the material matrix, resulting in embrittlement and other structural issues. While this discussion primarily focuses on fusion, it underscores numerous challenges that span physics and engineering, which must be addressed.
Moreover, system integration presents another challenge. It is no longer just about bench-top experiments; it involves translating theoretical concepts and research-based experiments into practical applications. Achieving this transition is certainly possible, but it requires careful planning, execution, and funding to navigate this development pathway.
Plasma applications sit at the intersection of conventional scientific disciplines, demanding contributions from physics, chemistry, and biology. This is certainly true for non-thermal plasma that have biomedical applications. In the context of fusion, collaboration among physics, engineering, computer science, and chemistry is crucial due to the high temperatures involved, as well as the plasma-surface interactions and material considerations necessary for reactor functionality.
The area of plasma computation is particularly exciting. Historically, plasma research has benefited from modelling using various methods that may treat the plasma as either particles or fluids, depending on the information required. The UK possesses significant expertise in plasma modelling, complete with community codes that address various aspects of plasma research. The relationship between experiments and computation has always been important, as it helps interpret experimental data to understand microphysics and allows us to create innovative theories, providing inspiration for experimental investigation. This collaboration between experimental work and computational modelling has been a long-standing convention in the field.
A promising development is digital twinning. In the context of fusion, this could create an entire virtual reactor within a digital environment, allowing us to assess its strengths, weaknesses, and potential failure modes without the need for a physical machine. This approach relies on both experimental and theoretical data to inform a wide range of interconnected models and will pose many computational challenges. Nevertheless, it presents an attractive option for both predictive and interpretive purposes when working with these systems. Digital twinning is a newly emerging area of computation gaining traction in the UK and beyond, which was covered at our IOP conference this year.
The research landscape: Strengths and weaknesses
The UK has a long-standing tradition in plasma physics, characterised by a strong academic community that is increasingly making its mark in industry as well. Although the community is relatively small, its impact is significant and extends beyond its size. This sector is on the rise, fuelled by numerous world-class institutions and companies.
We benefit from advanced national facilities, including laser plasma facilities, pulse power systems, and tokamaks. Additionally, industry plays a crucial role in this field by operating its own plasma devices and developing innovative research.
Despite the UK’s reputation for innovation, securing long-term funding for translational research that has a commercial impact remains challenging. Although we are progressing, there is still room for improvement in bringing practical plasma applications to market. Fortunately, we have experience in establishing robust public-private partnerships and recognise the importance of these collaborations in navigating future challenges.
Furthermore, issues arising from Brexit, such as talent retention and the UK’s attractiveness to international researchers and students, present additional challenges for our sector.
Harnessing plasma’s potential
There has been a substantial investment in fusion technology and fusion plasmas. Given our ambitions, growing and training the community is the most critical aspect. We aim to increase the number of professionals in the field from 2,500 to 5,000 to meet our needs. While this represents one of our biggest challenges, £50m is available through FOSTER, part of the Fusion Futures funding package, specifically to enable this growth. Academia, national labs and industry together currently play a crucial role in delivering that training and will continue to do so in the future.
Non-thermal plasma research is one of the most cutting-edge and promising areas, with a vast range of potential applications. To maximise this potential, we need sufficient support for these areas, particularly in building strong relationships between academia and industry to translate high-tech advancements into market solutions.
Plasma could become a vital industrial tool for the future, impacting various fields such as agriculture, water treatment, biomedical applications, semiconductors, propulsion solutions, and material functionalisation. The potential applications of plasma science and technology are just beginning to filter into public awareness, and there is much work ahead of us to generate excitement.
Please note, this article will also appear in the 22nd edition of our quarterly publication.
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