I received recently (3/13/2012) new funding from a grant proposal. The award is for $199,999 and is from the US Air Force Office of Scientific Research Space Power and Propulsion Program (http://www.wpafb.af.mil/library/factsheets/factsheet.asp?id=9235). The proposal is entitled "Coherent Acoustic Phonon Source: A Novel Diagnostic Probe for Plasma Thruster Erosion". I proposed to use a novel high-frequency (terahertz) pulsed acoustic source, that I have developed at Marshall, to probe the level of lattice defects produced in wall materials of ion thrusters. The defects are produced by the ion stream impacting the walls at glancing angles, thereby ultimately eroding the walls of the thrusters. My technique should be able to monitor extremely low levels of such defect production and thereby reduce the diagnostic timescale from 1000's of hours (current methods) to perhaps minutes (with the nanometer-wavelength acoustic wave as a probe). Scientific personnel at the US Edwards Air Force Base will arrange for my group to conduct timed exposures of thin layers of the rocket wall materials directly to the exhaust plumes. I will then return with the samples to measure the correlation between reduced transmission of the acoustic waves through these damaged layers. In addition, a collaborator in Aeronautical Engineering at the University of Michigan will help model the defect generation. This grant is a 'proof-of-principle' one, and by AFOSR standards, is relatively modest in budget. If we succeed in the one-year effort, we would be well positioned for major future funding. Let me know if you would like any further details.