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First beam demonstration of a conduction-cooled Nb3Sn superconducting rf photoinjector

Chunguang Jing1,*, Roman Kostin1, Yubin Zhao1, Pavel Avrakhov1, Ernie Knight1, Sam Posen2, Grigory Eremeev2, Timergali Khabiboulline2, Damon Bice2 et al.

Alexander Netepenko2, Gongxiaohui Chen3, Wanming Liu3, Eric Wisniewski3, Scott Doran3, John Power3, Tom Reid3, and Michael Kelly3

  • *Contact author: c.jing@euclidtechlabs.com
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Phys. Rev. Accel. Beams 29, 115201 – Published 12 November, 2026

DOI: https://doi.org/10.1103/bgwr-36wy

Abstract

We report on the first beam produced by the world’s first conduction-cooled superconducting radio frequency (srf) photogun. Over the past 5 years, Euclid, working in collaboration with Fermilab and Argonne National Laboratory, has been developing a continuous-wave (cw), 1.5-cell, MeV-scale, conduction-cooled srf photogun operating at 1.3 GHz. The primary objective of this effort is to demonstrate ultrastable electron beams for ultrafast electron microscopy/diffraction (UEM/UED) applications, enabled by the exceptional shot-to-shot stability achievable with srf technology compared to room-temperature rf photoguns. Although srf systems were historically too costly for industrial deployment, two recent advancements: Nb3Sn coatings and conduction cooling, have dramatically reduced system complexity and operating costs. This srf photogun is designed to deliver true cw rf operation while dissipating only ∼2  W of rf power, eliminating the need for a high-power rf system and significantly reducing facility footprint. This srf photogun also features a raised Nb3Sn backwall serving as the photocathode, removing the need for an external cathode insert. cw rf operation with limited repetitive beam has been demonstrated. In this paper, we present the first beam results from this system along with its cooldown performance, Q-slope behavior, synchronization characteristics, and initial beam parameters.

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Phys. Rev. Accel. Beams 29, 115201– Published 12 November, 2026
  • Received 31 July 2026
  • Accepted 16 October 2026
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