LCLSII Cryomodule Modal Testing at Jefferson Lab Kirk

LCLSII Cryomodule Modal Testing at Jefferson Lab Kirk Davis 11 January, 2017 LCLSII p. CM Workshop

Purpose • Design Verification on an as-built LCLSII cryomodule • Establish a baseline for design modifications that may be indicated following cryomodule acceptance testing in CMTF

Methodology • Perform industry standard impulse response modal testing of LCLSII p. CM string. • Excite vibrations using an instrumented modal test hammer. • Record excitation (force sensor) and response vibration (accelerometers) • Compute the frequency domain transfer functions • Analyze resonance frequencies and mode shapes

Test Equipment Impulse Hammer Triaxial Accelerometer (piezoelectric), 10 installed on the p. CM string

Data Acquisition Data Physics Mobilyzer™ : 24 Channels, simultaneous sampling at up to 49 k. Hz

Data Analysis Vibrant Technology MEScope™ modal analysis software: curve fitting, modal parameter estimation, mode shape animation

Sensor Installation, Cavities Cavity Beamline Flanges (x 8), FPC End

Sensor Installation, Gate Valves Beamline Gate Valves (x 2), bottom

Status • Three complete sets of string data have been taken: – String hanging from Upper Cold Mass on 4 -poster – Cryomodule in the test cave warm, no U-tubes – Cryomodule in the test cave warm, U-tubes in place Data analysis is in process