ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
This article discusses experimental studies of spark-generated shock wave propagation in CO-laser sustained optically pumped CO–Ar–O2 plasmas. The rotational-translational temperature of the plasma is measured by Fourier transform infrared emission spectroscopy. The electron density in the plasma is determined by microwave attenuation. The line-of-sight averaged density distribution across the propagating shock is detected by photoacoustic deflection (PAD). The measurements show that adding small amounts of oxygen (up to 0.1%) to the baseline optically pumped CO–Ar plasma increases the electron density and the ionization fraction by more than an order of magnitude (up to ne=0.9×1010 cm−3 and ne/N=0.8×10−8, respectively), while the gas temperature remains nearly constant, within 3%–5%. Therefore this approach allows varying the electron density in the plasma nearly independently of the gas temperature. The PAD measurements show considerable apparent weakening and dispersion of a shock wave propagating in the optically pumped plasma with a strong radial temperature gradient, compared to the shock propagating in a cold nonionized gas. However, varying the electron density independently of the gas temperature does not produce any detectable effect on the measured gas density distribution across the propagating shock. It is therefore concluded that the observed shock weakening is entirely due to the radial temperature gradient sustained by resonance absorption of the CO laser radiation near the centerline of the shock tube and is not affected by the presence of the charged species in the plasma. © 2002 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1435829
