The 21st Century Frontier of Particle Accelerator Technology

Abstract

Modern day RF particle accelerators were born in 1940s and 50s following World War II, stimulated by W. Hansen's invention of the MARK I electron linear accelerator at Stanford utilizing RF resonant cavities and powered by the klystron that had recently been invented by the Varian brothers. In the ensuing 75 years accelerators have become an engine of scientific discovery leading to experimental verification of the Standard Model for particle physics; to xray free-electron lasers for ultra-fast chemical and materials science; and to applications such as radiation oncology, industrial processing, and national security. The tremendous development of accelerator technology over the last half-century has even capitalized on developments such as superconducting RF technology to enable very high average power operation. We now find ourselves at the point where the current technology can no longer deliver the desired performance required in the future at a cost that is acceptable and within the desired size and power constraints. Understanding the coupling of particle beams, electromagnetic fields, materials properties, and plasmas underpins the future of accelerator science and technology. Exciting R&D is underway in numerous areas that has the promise of greatly increasing the science reach of high-energy physics accelerators as well as enabling a broad range of applications for smaller and even compact accelerators in areas that include industrial processing, medical, security, and others. Advancements are occurring in the understanding of accelerator materials properties, advanced electrodynamic accelerating structure topology, operation in new frequency regimes up to millimeter-wave/THz, high efficiency RF power generation, and advanced manufacturing that could dramatically improve the cost/capability curve for these systems. Unconventional approaches are also being considered that utilize accelerators powered by lasers and high energy electron beams to generate intense accelerating fields in silicon microstructures and plasmas. These technology developments and novel approaches seek to achieve breakthroughs in accelerating gradient, cost, and efficiency leading to a new era of discovery science and applications.