Plasma technologies

Definition

Plasma, often referred to as the fourth state of matter, is an ionised gas consisting of charged particles such as free electrons and ions, as well as neutral atoms. It makes up around 99 percent of the visible universe – for example, active stars and lightning. Plasma is generated by supplying energy to the gas, causing electrons to be released from the atoms. The targeted technical production of plasma paves the way for a wide range of industrial and medical applications. 

There are various different types of plasma. In high-temperature plasma, the particles – electrons and ions – have similar energies and can often be regarded as equilibrium plasma. Such plasmas exist at temperatures ranging from thousands to millions of degrees Kelvin – conditions in which many physical processes such as nuclear fusion take place more readily. Low-temperature non-equilibrium plasma, or LTNE plasma for short, is a variant of non-equilibrium plasma. It is characterised by the fact that the electrons have a much higher energy than the ions and the neutral particles and that it produces reactive chemical molecules at moderate temperatures. 

Current applications and opportunities

High-temperature plasma is used in nuclear fusion: If a plasma consisting of heavy hydrogen (deuterium) and superheavy hydrogen (tritium) is stably enclosed by magnetic fields at about 100 million degrees Kelvin, the two hydrogen isotopes fuse to form helium and a neutron, releasing large quantities of energy. Even though this application is still in the research stage, the economy is already benefiting from numerous spin-offs and advances in other areas. These include high-performance magnets for industrial and medical applications, new simulation methods, the development of improved materials and methods for surface treatment. 

Low-temperature non-equilibrium (LTNE) plasmas are characterised by the presence of high-energy electrons as well as low-energy ions and neutral atoms. These plasmas generate free radicals and reactive molecules even at low temperatures well below 1000 degrees Kelvin, and they can therefore be used with living organisms and heat-sensitive surfaces. At present, the treatment of easily accessible tumours and diabetic lesions is important from a medical perspective, while the key issue from an industrial standpoint is the processing and disinfection of surfaces. 

This scientifically and technologically challenging topic represents a major opportunity for Swiss science and industry, which are renowned for their high level of expertise in plasma physics and materials research: Fusion energy could secure and decarbonise energy supply in the long term. LTNE plasmas have great potential because they enable sustainable and chemical-free processes in industry, agriculture and medicine. Switzerland is well positioned to harness these opportunities with the research groups at EPFL, ETH Zurich and PSI. 

Challenges

Fusion research focuses on material stress caused by high-energy particles, the long-term behaviour of reactor components and the optimisation of plasma and its stability. It is yet to be demonstrated that fusion reactors of the size necessary for commercial applications can be built and operated reliably. Although research is not affected by the ban on the construction of new nuclear power plants, financial incentives are lacking. In addition, there is a shortage of trained specialists. For commercial use, it would be necessary to amend the constitution. 

With regard to LTNE plasmas, the interactions between plasma and biological systems are not yet fully understood. There is also a lack of regulatory standards for medical applications of plasma, which impedes commercialisation. Here, there is a need for close collaboration between science, industry and politics. 

Focus on industry

Plasma technologies pave the way for a wide range of applications in industry: In production, they allow not only the use of sustainable energy but also efficient surface sterilisation, which is particularly important in the food, medical technology and packaging industries. They also offer environmentally friendly and cost-effective solutions for the production of chemicals and pharmaceuticals. In agriculture and the food industry, plasma technologies improve seed germination and promote plant growth. At the same time, they extend the shelf life of foodstuffs by decontaminating surfaces and enable pest control without the use of pesticides. Companies that adopt this technology at an early stage can achieve environmental and economic benefits. 

Plasma technologies require highly specialised professionals in fields such as biology, chemistry, electronics, high-voltage engineering, materials science, plasma physics and robotics. These subjects are covered at the federal institutes of technology, although the number of graduates is relatively small. The working environment is interdisciplinary; however, the mindset required for working in interdisciplinary teams is not yet fully developed. Interdisciplinary projects help to pool expertise. 

International perspective

With the Swiss Plasma Center at EPFL, Switzerland is excellently positioned at the international level thanks to vital technical installations, particularly in the field of fusion research. Despite the de facto exclusion from the European Horizon Europe and Euratom programmes, which lasted until the end of 2024, Switzerland maintains a cooperation agreement with the ITER research infrastructure project, in which 33 nations are working together to build the world’s largest magnetic fusion reactor. 

Although researchers from Swiss institutions are part of international initiatives such as the European Cooperation in Science and Technology (COST), Switzerland lags somewhat behind countries such as India, the Netherlands and the US in relation to LTNE plasmas. Those countries are already focusing more on industrial applications, which are hampered by the funding landscape in Switzerland. 

Future applications

The further development of plasma technologies offers enormous potential. For example, fusion energy from high-temperature and high-energy equilibrium plasmas could secure the energy supply in the long term while also reducing carbon emissions. 

Their properties mean that low-temperature non-equilibrium plasmas pave the way for many new possibilities: The relatively low temperatures prevent thermal damage while still enabling effective chemical reactions. This is beneficial not only in medicine, but also in areas that were previously dominated by chemical- and energy-intensive processes. In agriculture, LTNE plasmas can be used for the surface sterilisation of seeds, the decontamination of soils and the production of fertilisers directly from the air and electricity. In the food industry, LTNE plasmas improve the quality of food by reducing the quantity of microorganisms or chemical residues without impairing product quality. 

Plasma – the fourth state of matter – could potentially serve as a key building block in a sustainable future. Such technologies offer huge potential for various industrial sectors, as well as numerous opportunities for industry and society. Seizing these opportunities will require investments in research, development and training, as well as increased interdisciplinary collaboration. Political support will be vital in order to establish Switzerland as a leading hub for plasma technologies and to fully exploit the potential of such technologies for a sustainable future.