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A numerical study of the acoustic radiation due to eddy current‐cryostat interactions
Author(s) -
Wang Yaohui,
Liu Feng,
Zhou Xiaorong,
Li Yu,
Crozier Stuart
Publication year - 2017
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1002/mp.12261
Subject(s) - eddy current , cryostat , electromagnetic shielding , acoustics , electromagnetic coil , vibration , noise (video) , reduction (mathematics) , finite element method , current (fluid) , noise reduction , materials science , mechanics , physics , structural engineering , engineering , computer science , geometry , superconductivity , image (mathematics) , mathematics , quantum mechanics , artificial intelligence , composite material , thermodynamics
Purpose To investigate the acoustic radiation due to eddy current‐cryostat interactions and perform a qualitative analysis on noise reduction methods. Methods In order to evaluate the sound pressure level (SPL) of the eddy current induced warm bore wall vibration, a Finite Element (FE) model was created to simulate the noises from both the warm bore wall vibration and the gradient coil assembly. For the SPL reduction of the warm bore wall vibration, we first improved the active shielding of the gradient coil, thus reducing the eddy current on the warm bore wall. A damping treatment was then applied to the warm bore wall to control the acoustic radiation. Results Initial simulations show that the SPL of the warm bore wall is higher than that of the gradient assembly with typical design shielding ratios at many frequencies. Subsequent simulation results of eddy current control and damping treatment application show that the average SPL reduction of the warm bore wall can be as high as 9.6 dB, and even higher in some frequency bands. Conclusions Combining eddy current control and suggested damping scheme, the noise level in a MRI system can be effectively reduced.