Nitrogen-Doped 9-Cell Cavity Performance in a Test Cryomodule for LCLS-II

Abstract

The superconducting RF linac for LCLS-II calls for 1.3 GHz 9-cell cavities with an average intrinsic quality factor Q0 of 2.7x10^10 at 2 K and 16 MV/m accelerating gradient. Two niobium 9-cell cavities, prepared with nitrogen-doping at Fermilab, were assembled into the Cornell Horizontal Test Cryomodule (HTC) to test cavity performance in a cryomodule that is very similar to a full LCLS-II cryomodule. The cavities met LCLS-II specifications with an average quench field of 17 MV/m and an average Q0 of 3x10^10. The sensitivity of the cavities' residual resistance to ambient magnetic field was determined to be 0.5 nOhm/mG during fast cool down. In two cool downs, a heater attached to one of the cavity beam tubes was used to induce large horizontal temperature gradients. Here we report on the results of these first tests of nitrogen-doped cavities in cryomodule, which provide critical information for the LCLS-II project.

11 pages, 22 figures

References in corpus (5)

• Nitrogen and argon doping of niobium for superconducting radio frequency cavities: a pathway to highly efficient accelerating structures
• Ultra-high quality factors in superconducting niobium cavities in ambient magnetic fields up to 190 mG
• Dependence of the residual surface resistance of superconducting RF cavities on the cooling dynamics around $T_{\mathrm{c}}$
• Reply to "Comment on the 'Decrease of the surface resistance in superconducting niobium resonator cavities by the microwave field'"
• Dependence of the microwave surface resistance of superconducting niobium on the magnitude of the rf field

Cited by in corpus (12)

• Unprecedented Quality Factors at Accelerating Gradients up to 45 MV/m in Niobium Superconducting Resonators via Low Temperature Nitrogen Infusion
• Efficient expulsion of magnetic flux in superconducting RF cavities for high $Q_0$ applications
• Sensitivity of Niobium Superconducting Cavities to Trapped Magnetic Flux Dissipation
• Effect of interstitial impurities on the field dependent microwave surface resistance of niobium
• Microwave Superconductivity
• Flux expulsion in niobium superconducting radio-frequency cavities of different purity and essential contributions to the flux sensitivity
• The Importance of the Electron Mean Free Path for Superconducting RF Cavities
• Magnetic Flux Dynamics in Horizontally Cooled Superconducting Cavities
• High-Q operation of SRF cavities: The potential impact of thermocurrents on the RF surface resistance
• Tuning microwave losses in superconducting resonators
• Frequency dependence of trapped flux sensitivity in SRF cavities
• RF surface resistance tuning of superconducting niobium via thermal diffusion of native oxide