Technique of suppression of bubble oscillation in marine seismic exploration in shallow water

Also, as electric spark and electrodynamic sources, used mainly in works of the upper part of the section, non-explosive sources, which have become widespread, include pneumatic sources. This type of sources meets all the requirements for geophysical equipment. The main problem of such kind of sources is the presence of intense pulsations, long duration of the emitted signals, as well as not very reliability of some clusters. Especially topical is the problem of pulsations during the shallow water acquisitions. The shallow water depth does not allow to extract the signature acceptable for the construction of the effective operator from the data due to the interference of pulsations from the direct wave with the bottom, and the suppression operator which extracted from the theoretical signature, often gives an unacceptable result. To solve the bubble oscillation problems in shallow-water acquisition, it is proposed to use combined information of bubble oscillation extracted from a direct wave, extracted from bottom reflection, waveform predicting deconvolution and adaptive subtraction algorithms.

THE TIME DIFFERENCE IN EMISSION OF LIGHT AND PRESSURE PULSES FROM OSCILLATING BUBBLES

Oscillations of spark-generated bubbles are studied experimentally. In this work, an attention is paid to the time difference in the radiation of light flashes and pressure pulses from a bubble at the final stages of the first bubble contraction and the early stages of the first bubble expansion. It is found that light and pressure pulses are not radiated synchronously. In some experiments, the light flashes are radiated before the pressure pulses by a few μs and in other experiments, the light flashes are radiated later than the pressure pulses by a few μs. The time difference in the radiation of the two pulses is examined in detail in relation with the bubble size, bubble oscillation intensity, maximum value of the light flash and the width of the light flash. It is shown that the magnitude of the time differences is very weakly correlated with the bubble size, intensity of oscillation and intensity of the light flashes and that the magnitude of the time differences is only moderately correlated with the light flashes widths.

Damage-Free Cleaning of Advanced Structure Using Timely Energized Bubble Oscillation Megasonic Technology

The use of highly corrosive chemicals to remove nano-particles on the surface of the wafer, results in substrate losses. This has resulted in the use of megasonics which provides acoustic cavitation to remove small particles. The megasonic wave does generate bubble cavitation which applies mechanical force to wafer structure, the violent cavitation such as transit cavitation or micro jet will damage the patterned structures [1,2]. A new megasonic technology is proposed in this paper, this technology provides stable control of bubble cavitation, without pattern damage at the different modes. The technology shows better particle performance when compared with the industry standard two-fluid nozzle cleaning technology. This Timely Energized Bubble Oscillation mode provides stable cavitation with a wide power window. It is unlike conventional megasonic which creates transit cavitation and damage when the bubble implodes. This new megasonic technology can be used to clean “sensitive” structures at 28nm and below without any pattern damage.