• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.1-7
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• 2011

Sound waves and acoustic energy generated by two identical TA (ThermoAcoustic) lasers were analyzed and studied. One end of the ceramic stack was heated by a thin NiCr wire wound around that end. The other end of the stack was cooled by natural convection of atmospheric air. The wavelength of the sound waves generated by a single TA laser was four times the tube length and the amplitude of the waves increased with the heating rate. SPL (SoundPressure Level) meters and microphones were employed to measure and study the sound waves at different distances from the glass tube opening and at the focusing point of the TA laser pair for different laser position arrangements. The sound waves of the two TA lasers at the focusing point were found to be almost 180 degrees out of phase when the openings of the two lasers were very close to each other and the angle between the laser axes was small. When the two TA lasers were placed far apart, the sound wave amplitudes and the phase difference between the two laser outputs varied periodically with time. The frequencies of the sound waves changed when the openings of the two TA lasers were in close vicinity and the angle between the laser axes exceeded a certain value. In this case, the glass tube opening was no longer a pressure anti-node and the wavelength of the fundamental mode was not equal to four times the tube length.