J. Wayne Jones

Professor Emeritus

jonesjwa@umich.edu

2022 Gerstacker

T: (734) 764-7503

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MURI: Hyperspectral and Extreme Light Diagnostics for Defense-Critical Advanced Materials and Processes

Sponsor: Air Force Office of Scientific Research
The overall objective of this new (summer 2005) MURI program is to develop the scientific basis for use of ultrafast lasers as materials diagnostic and microfabrication tools for critical components in advanced DOD systems. Of specific interest in this program are critical components in aircraft engines, which experience extreme combinations of stress and temperature, oxidizing environments, may experience in-flight impacts and require periodic damage inspections. In this program we will use the turbine blade as a vehicle for demonstrating the potential benefits of a hyperspectral diagnostic and microfabrication platform. Turbines blades have intricate geometrical design and are composed of a superalloy single crystal substrate to which layers of NiAl intermetallic and yttria-stabilized zirconia are applied for further environmental and thermal protection. The program will consist of several interrelated projects, each coupling an ultrafast technique with investigation of one or more class of material flaw(s). These projects will (1) improve the understanding of laser Ð material interactions for metallic, intermetallic and ceramic materials; (2) quantify the capabilities and/or extend the limits of individual laser-based material interrogation modes, including x-ray and electron based diagnostics, terahertz tomography and Ònon-destructiveÓ LIBs; (3) investigate the capability of each technique to detect a particular form of damage and (4) integrate the diagnostic techniques to track damage evolution and provide input to models for turbine blade life.Multispectral characterization is a key feature of the program. Using the plasma interaction between a focused relativistic intensity laser pulse and a solid material, the suitability of sub-picosecond bursts of partially coherent x-rays to operate at atmospheric pressure and detect several different classes of material damage will be investigated. In situ, real time monitoring of fatigue damage development during cycling at 20kHz (utilizing a synchronized x-ray source) will be demonstrated. The suitability of volume Bragg grating technology for generating high average power (to >100W) and high pulse energy (> 1 mJ) femtosecond optical pulses in a very compact and efficient arrangements will be tested. Time-resolved electron and x-ray imaging of laser-induced acoustic waves will also be investigated. Finally, diagnostic sources based on dynamics of plasmas illuminated in the tightly focused regime with relativistic intensity will be investigated along with potential uses of extreme fields without vacuum.Laser-Induced Breakdown Spectroscopy (LIBS) will be combined with other analysis techniques to demonstrate simultaneous detection of chemistry and damage. The ability of ultrafast double-pulse LIBS to ablate small amounts of material for analysis will be developed to make this technique effectively Ònon-destructiveÓ. The damage threshold of Ni based superalloy materials and ceramic Yttria Stabilized Zirconia (YSZ) coatings, will be studied as a function of laser (wavelength, pulse length) and material (porosity, grain size, defect structure) properties using double-pulse light. An improved fundamental understanding of laser-material interaction will be developed with the use of molecular dynamics and continuum hydrodynamic models. This will contribute to the definition of new microfabrication approaches, including micromachining, repair and creation of simulated flaws for advancement of life prediction methodologies. Finally, the ability of ultrafast lasers to uniquely create, receive, and apply pulses of millimeter- and submillimeter-wavelength broadband radiation (THz pulses) will be used to devise advanced diagnostics for detection of coating erosion and spallation.