The electron density and the electron collision frequency in a decaying plasma are deduced from the simultaneous recording of two microwave detector signals. The plasma is contained in a small diameter, cylindrical glass tube placed across a waveguide, on which the two detectors are located at some known positions. This method is applied to the decay of an usual pulsed DC discharge, and electron densities between 5 x 10
11 and 2 x 10
13 cm
-3 are measured by a 8300 MC. wave. It is also found that the electron temperature, except in its very early period, decreases more slowly than expected on the basis of the simple assumption of energy equipartition between electrons and ions.
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