Accession Number:

ADA164581

Title:

X-Ray Generated Ultrasound.

Descriptive Note:

Summary rept. 15 Apr 85-15 Jan 86,

Corporate Author:

CORNELL UNIV ITHACA NY DEPT OF THEORETICAL AND APPLIED MECHANICS

Personal Author(s):

Report Date:

1986-01-30

Pagination or Media Count:

64.0

Abstract:

This report describes the mechanisms by which ultrasonic signals are generated by an intense, pulsed x-ray source interacting with a material and how the associated contrast mechanisms can be used to image and characterize material microstructures. The existence of x-ray generated acoustic signals was verified and the beam-current dependence of the x-ray generated acoustic signals was established. The amplitudes of the acoustic signals appear to be linearly related to the electron beam current of the synchrotron and hence the x-ray intensity. Thus, the x-rayacoustic phenomenon could form the basis of an x-ray beam monitor sensor. The x-ray acoustic signals were also found to depend linearly on the beam size. The generated x-rayacoustic signals show a directivity pattern resembling that of the thermoelastic signals generated by a pulsed thermal laser source and they appear to be independent of beam width. A newly developed double modulation measurement technique analogous to existing photoacoustic spectroscopy PAS measurements is described. It was found that the x-rayacoustic spectra are material dependent. The measured scanned fields vary spatially, with features apparently related to the effects of the transducer or elastic wave resonances in the specimen. A preliminary test was completed with a new differential x-rayacoustic measurement technique by which transducer and specimen wave propagation effects were removed so that spatial features in a specimen could be clearly identified.

Subject Categories:

  • Acoustics
  • Nuclear Physics and Elementary Particle Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE