Key directions for research and development of superconducting radio frequency cavities

Abstract

Radio frequency superconductivity is a cornerstone technology for many future HEP particle accelerators and experiments from colliders to proton drivers for neutrino facilities to searches for dark matter. While the performance of superconducting RF (SRF) cavities has improved significantly over the last decades, and the SRF technology has enabled new applications, the proposed HEP facilities and experiments pose new challenges. To address these challenges, the field continues to generate new ideas and there seems to be a vast room for improvements. In this paper we discuss the key research directions that are aligned with and address the future HEP needs.

Future high energy colliders and options for the U.S.

“…Promising R&D directions are being pursued for increasing gradient, including new superconducting materials, travelling wave cavities, new cell shapes for standing wave structures, cleanroom robotics to reduce field emission, layered superconductor structures, and new impurity doping treatments, as well as more fundamental explorations of the limits of RF superconductivity, such as the use of "slow surface" materials that could prevent dissipation from magnetic flux penetration. For examples of SRF R&D directions, see references [102][103][104][105][106][107][108]. There are many exciting ideas to pursue.…”

RF Accelerator Technology R&D: Report of AF7-rf Topical Group to Snowmass 2021

“…The White Paper [21] outlines the key future research directions, which largely continue to align with the GARD roadmap. These include:…”

RF Technologies for Future Colliders

“…Since the development of baseline ILC technology, the SRF field has continued to make progress in several areas. The key directions for SRF cavity R&D to support future needs of high-energy physics are outlined in the recently published article [23]. Some of the recent advances and results expected in the near future can be applied to the ILC luminosity and energy upgrades [9,24,25] or to the recently proposed HELEN collider [10].…”

“…There was a rapid progress in developing advanced surface treatments over the last decade [23]. Most notably, a nitrogen doping technology allowed reaching unprecedented high-quality factors greater than 3 • 10 10 at 2 K and medium gradients for freeelectron laser linacs LCLS-II and LCLS-II-HE [26] (1.3 GHz cavities) and proton SRF linac PIP-II (650 MHz cavities) [27].…”