Particle Accelerators: machines that generate extremely fast beams of sub-atomic particles are among the most powerful engines of scientific progress, of medical imaging and therapies, and of screening for industry and security. Reducing the size and cost for future accelerators is crucial to make the advanced capabilities developed in large scientific facilities available to such applications. For example, X-ray images could be taken with much greater resolution and reduce radiation dose, improving medical and security applications. Reduced size would also enable construction of higher energy systems, extending the reach of basic science in understanding the structure of the universe through high-energy particle physics. These fundamental interactions are at the heart of physics and the physical sciences.
Laser-Plasma Accelerators: a new generation of particle accelerators using intense lasers that drive waves in ionized gases (plasmas) has demonstrated the ability to create high energies in thousands of times shorter distances which could enable the new, compact systems that are needed. These accelerators have however been limited by the capacities of the required laser drivers, which currently fire only once per second. Much higher rates are needed both for the average beam intensity required by applications and for machine learning and active feedback to improve performance.
Intense Laser Technology: rapid progress in the high intensity, short pulse lasers that drive plasma accelerators has been enabled by new techniques that were developed in the United States and were awarded the 2018 Nobel prize in Physics. In recent years, other nations have leapt ahead of the US in the field of high-intensity lasers in recent years. High-repetition rate systems are a key opportunity to re-establish US leadership, supporting both near-term progress and the roadmap towards higher performance and higher repetition rates. Construction of a high repetition rate system, firing a thousand times a second, is now realistic due to recent advances in laser components.
kBELLA: a new project is proposed to build a high intensity short pulse laser at high repetition rate, to advance plasma accelerators and other applications. This includes a new facility that provides radiation shielding compatible with high rate operation. It would be a major milestone on the US plasma accelerator roadmap and timely execution is critical to retain US leadership within a highly competitive international environment developing these new technologies. This would enable applications with broad cross-federal and industrial/medical impact. It would support a future user facility, as well as future laser development.