Welcome to the UIUC Chemical Laser Group's homepage on the World Wide Web. Comments or questions should be sent to sentman@uiuc.edu.
VertiCOIL at UIUC
As part of an STTR program with STI Optronics, the Directed Energy Directorate of the Air Force Research Lab (AFRL) transfered the 2-kWatt VertiCOIL device to UIUC. AFRL demonstrated 27% chemical efficiency with VertiCOIL using helium diluent. UIUC is engaged in COIL commercialization efforts. These studies involve optimizing COIL efficiency with nitrogen diluent using new nozzle design concepts. UIUC demonstrated 23% chemical efficiency using room temperature nitrogen diluent; this is the highest reported efficiency with room temperature nitrogen diluent.
High Power Laser Cutting Experiments
A COIL was used at AFRL for cutting aluminum and carbon steel. Cut depths of 20mm were obtained in aluminum and 41mm in carbon steel using an N2 gas assist and 5-6 kW of power on target. The same laser at the same power level produced a cut depth of 65mm in carbon steel; a low quality cut to a depth of nearly 100mm in carbon steel was also demonstrated. COIL cuts carbon steel and stainless steel at approximately the same rate. For a given cut depth, power and spot size, COIL cuts steel approximately three times faster than a CO2 laser using an inert gas assist. COIL cutting speeds in carbon steel are improved by approximately a factor of three when an O2 assist is used in lieu of an N2 gas assist. With an N2 gas assist, COIL cuts aluminum at approximately the same rate as CO2 cuts steel.
CFD Modeling of COIL Flow Fields
The 3D computational fluid dynamics (CFD) Navier-Stokes General Aerodynamic Simulation Program (GASP) was used to model low (70 Torr) and high (130 Torr) total pressure COIL flows. The details of the calculation show complete mixing in the laser cavity region at low pressure, but incomplete mixing at higher pressures. These calculations demonstrated the importance of including the pressure diffusion term in the computation of diffusional mixing; this was the first time that the pressure diffusion term has been successfully implemented into a CFD model. Calculations have shown that it is possible to improve the uniformity of mixing in the nozzle at high pressure by increasing the number of injectors.
- Click here for images and more information about the CFD modeling.
High Pressure Predictions of RADICL Performance
A genetic algorithm technique was used for the first time for modeling chemical lasers, chemically reacting flows and lasers. These modeling predictions indicate that substantial power levels should be obtainable with a COIL device at high pressures (100-200 Torr).
Overtone HF Tests
Demonstrated the highest HF overtone efficiency (70-90%) to date. Developed a new method of accurately measuring the reflectivity of highly reflective (>98%) mirrors. First to measure small signal gain of the fundamental transitions while simultaneously lasing at the overtone wavelengths.
Line-Selected Fundamental HF Experiments
Presently measuring the laser performance of selected pairs of fundamental transitions. Modeling predictions indicate that it may be possible to obtain as much as 60% of the multi-line power (typically 6-8 lines) with only two lines lasing simultaneously.
Side Wall Injection Nozzle Testing
Measuring the performance of a chemical laser nozzle bank with side wall injection versus parallel slit nozzle mixing. Preliminary experiments suggest that this nozzle may have approximately a 50% improvement in performance above the old supersonic (SSL) nozzle bank for the same cavity pressures.
People in the UIUC chemical laser group.
[UIUC Aeronautical and Astronautical Engineering Department]