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SOME EFFECTS OF FLUID MOTION ON THE PROPAGATION OF ELECTROMAGNETIC WAVES
AEROSPACE CORP EL SEGUNDO CALIF
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Physical arguments were given to deduce that when an electromagnetic wave propagates through a flowing gas, the response of a typical electron to the electric field associated with the wave would be different from that which would occur if the gas were stationary. An analysis indicates that this is indeed the case even if the fluid velocities are nonrelativistic. The change in the propagation characteristics of the gas were determined for several limiting cases of collision frequency, plasma frequency, and signal frequency. The effect of nonrelativistic fluid velocities was found to be small unless the plasma frequency is much greater than, andor the collision frequency is much less than, the signal frequency. It was also found that an additional mode of propagation exists due to the fluid velocity. This mode propagates essentially with the fluid velocity and is very highly damped unless the collision frequency is very small. The third mode damps to 1e times its original value in a distance which is of the order of the ratio of the convective velocity to the collision frequency. Author
APPROVED FOR PUBLIC RELEASE