Acoustic waves and heating due to molecular energy transfer in an electric discharge CO laser

Culick, F. E. C.; Shen, P. I.; Griffin, W. S.

doi:10.1109/jqe.1976.1069042

Cited by 9 publications

(2 citation statements)

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“…For such small values of E=N the fraction of input energy that goes into gas heating increases rapidly to about 90% [30], which is close to the value observed in [28]. A direct measurement of the fraction of input energy that goes into gas heating is performed in [34,35]. Gas heating of pulsed N 2 plasma at 300 K and at different E=N values was studied both theoretically and experimentally in [34].…”

Section: Nonequilibrium Effects In the Dischargesupporting

confidence: 52%

“…A direct measurement of the fraction of input energy that goes into gas heating is performed in [34,35]. Gas heating of pulsed N 2 plasma at 300 K and at different E=N values was studied both theoretically and experimentally in [34]. Based on these results, we observe that only about 10% of input energy goes toward gas heating, whereas 90% goes into vibrational excitation.…”

Section: Nonequilibrium Effects In the Dischargementioning

confidence: 98%

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Characterization of a High-Frequency Pulsed-Plasma Jet Actuator for Supersonic Flow Control

2010

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An experimental study is conducted to characterize the performance of a pulsed-plasma jet (called a "spark jet" by other researchers) for potential use in supersonic flow control applications. A pulsed-plasma jet is a high-speed synthetic jet that is generated by striking an electrical discharge in a small cavity. The gas in the cavity pressurizes owing to the heating and is allowed to escape through a small orifice. To obtain an estimate of the relative strength of the pulsed-plasma jet, the jet is injected normally into a Mach 3 crossflow and the penetration distance is measured by using schlieren imaging. These measurements show that the jet penetrates 1.5 boundary-layer thicknesses into the crossflow and the jet-to-crossflow momentum flux ratio is estimated to be 0.6. A series of experiments was conducted to determine the characteristics of the pulsed-plasma jet issuing into stagnant air at a pressure of 35 torr. These results show that typical jet velocities of about 250 m=s can be induced with discharge energies of about 30 mJ per jet. Furthermore, the maximum pulsing frequency was found to be about 5 kHz, because above this frequency the jet begins to misfire. The misfiring appears to be due to the finite time it takes for the cavity to be recharged with ambient air between discharge pulses. The velocity at the exit of the jet is found to be primarily dependent on the discharge current and independent of other discharge parameters such as cavity volume and orifice diameter. Temperature measurements are made using optical emission spectroscopy and reveal the presence of considerable nonequilibrium between rotational and vibrational modes. The gas heating efficiency was found to be 10% and this parameter is shown to have a direct effect on the plasma jet velocity. These results indicate that the pulsed-plasma jet creates a sufficiently strong flow perturbation that holds great promise as a supersonic flow actuator.Nomenclature j = density of the pulsed-plasma jet 1 = freestream density u j = exit velocity of the pulsed-plasma jet u 1 = freestream velocity

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