title: Temperature modes for nonlinear Gaussian beams.
abstract: In assessing the influence of nonlinear acoustic propagation on thermal bioeffects, approximate methods for quickly estimating the temperature rise as operational parameters are varied can be very useful. This paper provides a formula for the transient temperature rise associated with nonlinear propagation of Gaussian beams. The pressure amplitudes for the Gaussian modes can be obtained rapidly using a method previously published for simulating nonlinear propagation of Gaussian beams. The temperature-mode series shows that the nth temperature mode generated by nonlinear propagation, when normalized by the fundamental, is weaker than the nth heat-rate mode (also normalized by the fundamental in the heat-rate series) by a factor of log(n)/n, where n is the mode number. Predictions of temperature rise and thermal dose were found to be in close agreement with full, finite-difference calculations of the pressure fields, temperature rise, and thermal dose. Applications to non-Gaussian beams were made by fitting the main lobe of the significant modes to Gaussian functions.
authors: Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland 20993, USA.
authors: Matthew R
authors: MR
authors: Myers
authors: Joshua E
authors: JE
authors: Soneson
mesh_terms: D000162:Acoustics; D000465:Algorithms; D004058:Diffusion; D005583:Fourier Analysis; D006358:Hot Temperature; D008962:Models, Theoretical; D016011:Normal Distribution; D011312:Pressure; D013696:Temperature; D013997:Time Factors; D014465:Ultrasonics