Mitigation of Oxygen Attachment in High Pressure Air Plasmas by Vibrational Excitation

Kraig Frederickson, Wonchul Lee, Igor Adamovich, J. Rich, Walter Lempert, P. Palm
2004 35th AIAA Plasmadynamics and Lasers Conference   unpublished
We present a series of measurements of the temporal evolution of electron density in high pressure, room temperature pulsed e-beam generated molecular plasmas. We show that vibrational excitation, to T vib of order 2,000 -3000 K, results in nearly complete mitigation of direct O 2 attachment, which is the principal free electron loss process under equilibrium conditions. Spatially and temporally resolved temperature measurements, performed using spectrally filtered pure rotational Raman
more » ... ional Raman scattering, indicate heavy species rotational/translational temperature is only slightly increased as a result of vibrational excitation, to approximately 350 K. Kinetic modeling of two limiting cases, accelerated detachment and inhibited attachment, suggests that two non-equilibrium mechanisms may be playing a role simultaneously: i), detachment enhancement by collision of O 2 -(or other negative) ions with vibrationally excited neutrals, and ii), attachment inhibition due to electron heating by superelastic collisions with vibrationally excited neutrals.
doi:10.2514/6.2004-2257 fatcat:qa2aen3w4ra3hfbe6kk5txvdpm