Accelerator scientists from across Europe are collaborating on the world’s first high energy plasma-based accelerator, which will be stronger and more compact than the current accelerators used by industry today. It is hoped that the new technology will open up opportunities to use the beams for entirely new types of applications.
The consortium that will develop the 5GeV plasma-based accelerator is made up of 16 institutions and 18 associated partners from more than eight countries, known as EuPRAXIA.
In physics, plasma is an electrically conducting medium with positively and negatively charged particles. It is referred to as the fourth state of matter after solid, liquid and gas and can be created from a gas by applying high energy. Nearly all visible matter in the universe is in a plasma state (for example the sun is a plasma star).
Plasma is the most effective known transformer of an electromagnetic wave, and plasma accelerators can sustain an electric field up to 10,000 times greater than more conventional radio frequency (RF) accelerators in a much shorter distance.
There is significant interest in reducing the size and costs of current accelerators to make them more accessible to industry.
EuPRAXIA will direct a laser through a plasma medium, creating a wave and forcing the electrons within the plasma to create a strong electric field. Oscillating between the transverse field of an electromagnetic wave and the longitudinal field of a plasma wave accelerates the electrons, creating a high quality beam.
Still from Bringing Light Into Research Laser Plasma Accelerators: The Revolution, Victor Malka, Lasers for Science and Society Symposium
EuPRAXIA is an important intermediate step between proof-of-principle experiments and ground-breaking, ultra-compact accelerators for science, industry, medicine or the energy frontier.
The work carried out by the consortium, according to Professor Carsten Welsch, a member of the project’s management team, ‘includes for example beam dynamics studies that help better understand beam-plasma matching, as well as the development of innovative diagnostics to fully characterise all aspects of the plasma and the beam.’
Although there has been academic research into plasma-based high gradient accelerators, no infrastructure exists where the quality of the accelerated beam satisfies the requirements of industry. Creating such a facility would be a major breakthrough and would attract users from many different sectors, Welsch added: ‘Many additional applications across material and life sciences, chemistry and surface studies come into reach.’
One potential application is for non-destructive testing (NDT). By applying high-resolution radiography to a dense object, it would be possible to inspect the object without destroying its material capacities and strength. NDT within the aircraft industry, for example, can show defects or changes in thickness of the structure, providing early warning of corrosion and erosion. A compact, higher energy accelerator would be very desirable for NDT applications and allow new types of testing.
Another application is the production of free electron lasers (FELs), these are laser-like flashes of radiation, which can be used to decipher biomolecule structures and explore nanoparticles.
Plasma accelerator technology is still in the proof-of-principle phase, and several feasibility and practicality issues must be considered before it can be fully operational in industry.
However, Professor Welsch is hopeful that perfecting plasma accelerators will drive a significant increase in industrial applications that require high quality beams.
‘An important aspect of EuPRAXIA is to identify the exact user, experiment and application needs and determine where a plasma accelerator provides major benefits,’ he remarked.