Limitations on the Use of Acoustic Sensors in RF Breakdown Localization
  X-band accelerator structures, meeting the Next Linear Collider (NLC) design requirements, have been found to suffer damage due to radio frequency (RF) breakdown when processed to high gradients. Improved understanding of these breakdown events is desirable for the development of structure designs, fabrication procedures, and processing techniques that minimize structure damage. Using an array of acoustic sensors, we have been able to pinpoint the location of individual breakdown events. However, a more accurate localization is required to understand the interaction between the phonon or the sound wave with the OFE copper. 
F. Le Pimpec