Pressure Damping for Pulsed Electric Discharge Laser.
Abstract
The electric discharge in a pulsed electric discharge laser (EDL) produces density disturbances in the gaseous medium which significantly alter the refractive index of the medium and seriously degrade laser beam quality. The use of acoustic absorbers and honeycomb flow conditioners to quickly damp the disturbances in the EDL has shown promise. An experimental study was conducted to further investigate the use of acoustic absorbers and honeycomb flow conditioners as attenuation devices in pulsed EDLs. A plexiglass model of a typical EDL, full scale in two cavity dimensions, was used for the experimental evaluations. This model was readily varied to provide for: (1) various aperture area and resonator volume acoustic absorbers behind the 'anode' area, (2) the addition of CERCOR (glass ceramic) thicknesses of 0.5 inch and 3.0 inches in the flow channels immediately upstream and downstream of the cavity, and (3) various types of flow duct terminations (i.e., open, closed, partially closed, and plenum closed). The discharge was simulated with an explosive charge, and pressure oscillation damp times were determined for various model configurations. A total of 200 pulse tests was conducted on various model configurations. An analysis of AFWL data and the Rocketdyne acoustic model data led to the conclusion that laser cavity modes (2 to 3 kHz) exert relatively little influence in the attenuation of the pressure oscillation. The predominant frequency apparent in the data (less than 1 kHz) is related to flow channel modes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1976
- Accession Number
- ADA038628
Entities
People
- R. Kesselring
- R. March