Error analysis of vertical test for CEPC 650 MHz superconducting radio-frequency cavity

TL;DR

This paper analyzes the errors in vertical testing of 650 MHz SRF cavities for CEPC, quantifying uncertainties in key performance metrics to ensure accurate evaluation of cavity quality.

Contribution

It provides a detailed error analysis of vertical test measurements, improving the accuracy of Q0 and Eacc evaluations for superconducting RF cavities.

Findings

Vertical test uncertainties are approximately 3% for Eacc.

Uncertainty in Q0 measurement is less than 5%.

Results confirm the reliability of the vertical test method.

Abstract

Hundreds of 650 MHz superconducting radio-frequency (SRF) cavities with high intrinsic quality factor (Q0) and accelerating gradient (Eacc) will be adopted for Circular Electron Positron Collider (CEPC). The values of Q0 and Eacc are obtained during vertical test at 2.0 K. Hence, high accuracy of vertical test is essential for evaluating the performance of SRF cavity. The 650 MHz SRF cavities achieved very high Q0 (6E10) and Eacc (40 MV/m) during the vertical test. In our study, the error analysis of vertical test was conducted in the scalar case, in order to achieve high accuracy. The uncertainties of vertical test were obtained through calculation, which was approximately 3% for Eacc and less than 5% for Q0. This result was reasonable and acceptable.