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Published on: January 13, 2018
Stimulated effects in N(2) and CH(4) gases
T A Wiggins1, R V Wick, D H Rank
1Physics Department, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Researchers observed stimulated Brillouin scattering in nitrogen and methane using a giant-pulse laser. This study quantifies scattering parameters and measures sound speeds in these gases at lower pressures than previously reported.
Area of Science:
- Physics
- Laser-induced phenomena
- Spectroscopy
Background:
- Stimulated Brillouin scattering (SBS) is a nonlinear optical process.
- Previous studies were limited by laser amplification of back-scattered radiation.
- Quantitative analysis of SBS parameters requires isolating the back-scattered signal.
Purpose of the Study:
- To quantitatively study parameters affecting stimulated Brillouin scattering.
- To investigate SBS in nitrogen (N2) and methane (CH4) under specific experimental conditions.
- To measure the speed of sound in CH4 and N2 at lower pressures.
Main Methods:
- Utilized a giant-pulse laser setup designed to prevent amplification of back-scattered radiation.
- Observed and analyzed stimulated Brillouin scattering in N2 and CH4.
- Measured spectral width and duration of the Brillouin component.
- Determined the back-scattered power percentage.
Main Results:
- Successfully observed SBS in N2 and CH4 without laser amplification of back-scattered light.
- The back-scattered Brillouin component exhibited a narrow spectral width (one-third of the laser's) and short duration (nanoseconds).
- Nitrogen (N2) at high pressure demonstrated significant back-scattering, up to 45% of incident power.
- Measured speeds of sound in CH4 and N2 at pressures lower than previously reported.
Conclusions:
- The experimental setup enables quantitative studies of SBS parameters.
- SBS characteristics, including spectral width and duration, are influenced by gas properties and pressure.
- This work provides new measurements for the speed of sound in N2 and CH4, extending the range of reported pressures.
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