Abstract
When a plasma column of an equal number of ions and electrons was placed in a beam of microwave power then, under suitable conditions which were derived, there was an interaction between the microwaves and the electrons in the plasma column. A K-band microwave spectrometer was built in an enclosed parallel plate transmission line system, with a fixed horn and a variable position receiver. A beam of power was directed onto the cylindrical plasma column in the absence of static magnetic fields and with the electric field vector parallel to the plasma axis. The plasma electron density was swept at 50 c/sec., giving a peak density of the order of 8 x 10[18] electrons/metre[3]. The angular scattering of the microwave beam by the plasma column was measured in detail, to determine the variation of the total power within the system as a function of the electron density. The final graph showed two regions with greater absorption of microwave power; one corresponded to the plasma frequency criterion, whilst the other occurred at half this critical electron density. From similar traces obtained over the region 22-26 Gc/sec., the linearity relationship between the electron density and the discharge current was demonstrated. The scattering pattern from the plasma column was more consistent with a geometric optical theory than with a simplified wave theory, even though the column radius was only one and a half wavelengths.