More than 47,000 particle accelerators are in operation worldwide, including large-scale facilities for particle physics, synchrotron light sources, and thousands of accelerators used in industry and health care, with applications ranging from food preservation and industrial material processing to medical diagnosis and therapy with electrons, ions, neutrons and X-rays.
Those particle accelerators rely on mature technology that delivers high-quality particle beams with good efficiency. However, their energy is often limited by practical boundaries, e.g. available space in hospitals or the cost society can afford for fundamental research projects.
A reduction in size and cost will increase dramatically the application reach and benefits of accelerators. In addition, the numerous present and future accelerator-based infrastructures need a generational leap forward in terms of optimised power consumption and reduced environmental footprint.
The PACRI project addresses several crucial aspects of particle acceleration for reducing the size of accelerator-based facilities, including:
- High-efficiency, high-repetition-rate power sources.
- High-gradient, high-current, high-repetition-rate acceleration in RF and plasma modules.
- High-power laser drivers for plasma accelerators.
In recent years it has been shown that plasma wakefield accelerators such as the ones developed by the EuPRAXIA consortium, can accelerate charged particles in lengths reduced by a factor 100 – 1,000. The work in PACRI plays a crucial role in complementing EuPRAXIA, further developing and strengthening RF, laser, plasma and diagnostic technologies needed to get optimum performance from plasma accelerators at high repetition rate.
Scientific impact
Research fields that are directly impacted by plasma accelerators and high efficiency, high repetition rate accelerators include:
- photon science
- structural biology
- particle physics detector development
- material science
- medical imaging
- etc.
High-power high-repetition-rate lasers. The availability of industry-grade, high repetition rate ultrashort pulse lasers as drivers of plasma wakefields will lead to a rapid further diffusion of advanced accelerators and light sources. Combined with advances in plasma technology, the development of high-power lasers will give rise to a new approach to the investigation of fundamental physics aspects requiring high quality and reproducibility.
Contributions to EuPRAXIA. PACRI plays a crucial role in complementing the EuPRAXIA construction project included in the ESFRI roadmap, further developing, and strengthening the integration of RF, Laser, and Plasma technologies needed to drive the Plasma Accelerating Modules at a high repetition rate.
Plasma-based colliders. Progress in particle colliders is limited by practical considerations on size and cost. Plasma accelerators might offer a more affordable alternative. Although beam quality currently achievable by plasma technology cannot compete with frontier accelerators, every new development in this field is a stepping stone towards plasma-based linear colliders.
Compact FELs. Free Electron Lasers can produce short bursts of electrons and X-rays with the ability to map the atomic structure and electronic properties of molecules, materials and nanodevices. Reducing the cost and increasing the efficiency and repetition rate of FELs not only allows faster data acquisition, but also improves the temporal stability of the system.
Inverse Compton Scattering (ICS) X-ray source. Large-scale synchrotron facilities are the driving force in developing new X-ray imaging techniques that overcome the limits of conventional absorption imaging. Although many of these techniques provide benefits for medical X-ray imaging, most of them have not been implemented in clinical routines because they rely on properties which are only provided by synchrotron radiation.
An Inverse Compton Scattering (ICS) source, with operating frequency up to kHz, capable of producing such radiation with a small footprint, low expenses for cost, operation and maintenance, will have a high impact in these fields.
Education and jobs. PACRI directly supports more than a dozen early stage researchers. In addition, several partners involve externally-funded PhD students in their activities. PACRI enables a large number of students to take part in applied R&D and form the next generation of accelerator scientists and engineers, strategically strengthening the position of Europe in the global competition for talent.
Societal impact
The development of accelerator science and its impact on other technologies have become essential for our day-to-day lives. More than 400 B€ of end products are produced, sterilised or examined every year using industrial accelerators worldwide. More than 24,000 particle accelerators have been built globally over the past 60 years to produce charged particle beams for use in industrial processes. This number does not include the more than 11,000 particle accelerators produced exclusively for medical therapy with electrons, ions, neutrons, or X-rays.
Around 200 accelerators are used for research worldwide, with an estimated yearly consolidated cost of 1 B€ (www. accelerators-for-society.org). High-efficiency and high-repetition rate plasma technology will reduce the cost, size and environmental impact of particle accelerators considerably, multiplying their reach and applications in domains ranging from manufacturing to healthcare, serving the needs of hospitals and universities as well as museums and industries.
Examples of highly impactful applications of plasma accelerators include:
- Very-High-Energy Electron Therapy (VHEET). Wakefield accelerators with their reduced footprint are considered an interesting source of electrons for VHEET.
- FLASH radiotherapy (FLASH-RT) is a novel cancer therapy method that could be adapted for plasma accelerator-driven Inverse Compton Scattering sources. It applies high-intensity doses in a much smaller timeframe than conventional radiotherapy.
- Phase contrast imaging. The radiation sources driven by plasma accelerators, either in the form of Free Electron Lasers or broadband betatron radiation would be able to provide compact and versatile set-ups for medical imaging.
- Protein crystallography. Ultrashort X-ray pulses produced by Free Electron Lasers or Inverse Compton Scattering sources driven by plasma accelerators can be used to determine the structure of biomolecules with unprecedented time resolution. X-ray diffraction is also used in the pharmaceutical industry to determine the crystal structure of drug substances.
- Positron annihilation lifetime spectroscopy (PALS) for non-destructive, sub-surface volumetric inspection of materials. Plasma accelerators are able to generate the high-flux, short, mildly relativistic positrons that are required for PALS.