Abstract
The wave equation for pressure that governs generation of the photoacoustic effect possesses a forcing term proportional to the time derivative of the energy delivered to the gas per unit volume and time. A positive pressure fluctuation, with its accompanying density increase, thus increases the optical absorption and provides a positive feedback mechanism for sound generation. A theory for self-oscillation in a one-dimensional resonator is given. Expressions for the photoacoustic pressure are derived for the cases of highly and weakly absorbing gases that indicate mode-locked sound generation. Experiments with lasers are reported where evidence of the self-generation effect was sought.
- Received 25 April 2014
- Revised 2 July 2014
DOI:https://doi.org/10.1103/PhysRevE.90.043204
©2014 American Physical Society