Mechanical vibration in "double-wound" magnetic field exposure coils.
It has been suggested that "double-wound" (bifilar) exposure coils are capable of producing a sham environment in which hum and vibration will be "similar" to the field-exposed condition. We found by direct measurements in a bifilar coil system that vibration amplitude in sham and exposed conditions differed by a factor of 50 when our test system was driven at B = 10 mT. We also found that the normal laboratory environment can include vibrations of an intensity similar to that produced by the exposure system, although not necessarily of similar spectral distribution.
Jones
R A
RA
J.L. Pettis Memorial Veterans' Medical Center, Loma Linda, California 92357, USA.
Walleczek
J
J
Adey
W R
WR
D000054:Acceleration; D004780:Environment, Controlled; D004781:Environmental Exposure; D004867:Equipment Design; D007753:Laboratories; D008280:Magnetics; D012815:Signal Processing, Computer-Assisted; D013016:Sound; D017550:Spectroscopy, Fourier Transform Infrared; D014732:Vibration