Scattering of Microwaves from a Plasma Column in Rectangular Waveguide

The microwave reflection method for the measurement of various parameters of cold plasma is examined. The exact solutions are obtained for the waves scattered by a plasma column inserted in the duct. The probing electric field of T E 10 mode is parallel to the axis of the column. The emphasis is placed on the fact that inhomogeneous electron density distribution is fully taken into account. The electron density in the column is assumed to be n ( r )= n 0 (1- r 2 /ρ 2 ), where ρ is the radius of the column and n 0 is the electron density on the axis of the column. The electric permeability is then locally defined with use of n ( r ). Numerical calculations of reflection coefficients are carried out with the electronic computer OKITAC–5090 and their results are tabulated for such parameters as ω p /ω, ν/ω, k a , and k ρ for practical convenience. The electron densities in a positive column determined by the microwave reflection method with use of the tables are compared with those determined by the Langmuir probe method. The comparison is found in satisfactory agreement.