Comment on "calibration procedure to correct for the effect of dielectric containers in microwave plasma density measurements"

In a recent issue of this journal Wellenstein, Frommhold, and Robertson identified two reasons for systematic error in microwave electron density measurements and described a calibration procedure to eliminate the error. In this paper, use of a polar gas for calibration purposes is recommended and the choice of suitable cavity modes for this measurement technique is discussed. © 1973 American Institute of Physics.