Calibration of the ERL cavity FPC and PU couplers

Hahn, H. ; Johnson, E. ; Kayran, D.

关键词: CALIBRATION;    CRYOGENICS;    DEWARS;    ENERGY RECOVERY;    LINEAR ACCELERATORS;    PERFORMANCE;    QUALITY FACTOR;    SCATTERING;    SIMULATION;    SUPERCONDUCTING CAVITY RESONATORS;   

DOI  :  10.2172/1013467
RP-ID  :  BNL--91259-2010-IR
PID  :  OSTI ID: 1013467
Others  :  R&D Project: KBCH139
Others  :  Other: KB0202011
Others  :  TRN: US1102663

学科分类：核物理和高能物理

美国|英语

来源: SciTech Connect

【 摘 要 】

The performance parameters of a superconducting cavity, notably accelerating field and quality factor, are first obtained in a cryogenic vertical test Dewar, and again after the final assembly in its cryostat. The tests involve Network Analyzer (NA) measurements in which the cavity is excited through an input coupler and the properties are obtained from the reflected signal at the input and the transmitted signal from the output coupler. The interpretation of the scattering coefficients in terms of field strength requires the knowledge of the Fundamental Power Coupler (FPC) and Pick-Up (PU) coupler strength, as expressed by their 'external' and Q{sub FPC} Q{sub PU}. The coupler strength is independent of the field level or cavity losses and thus can be determined at low levels with the scattering coefficients S{sub 11} and S{sub 21}, assuming standard 50 {Omega} terminations in the network analyzer. Also needed is the intrinsic cavity parameter, R{sub a} /Q{sub 0} {triple_bond} {l_brace}R/Q{r_brace}, a quantity independent of field or losses which must be obtained from simulation programs, such as the Microwave Studio.