A method for damping unwanted bubble oscillations from a horizontally
towed seismic air gun is presented. The air bubble is destroyed by a p
erforated screen mounted at an optimal radius about the gun. Once the
primary pressure peak has been generated by the emerging bubble, the b
ubble continues to expand and is destroyed by the screen, leading to a
corresponding decrease in the measured pressure amplitude of the seco
ndary bubble oscillations. For a stationary gun fired first without, a
nd then with, the screen fitted, the primary-to-bubble ratio improves
in the near held from 1.7 to 5.2, respectively, at a firing depth of 3
m and from 1.5 to 5.5, respectively, at 5 m depth. The primary-to-bub
ble ratio for a towed air gun in the quasi-far-field improves from 2.0
to 11.0 at 4 m depth and from 1.5 to 8.7 at 7 m depth when the screen
is fitted. The boat speed was 1.6 knots and the signatures were filte
red with an out-128 Hz (72 dB/Oct) DFS V filter.