Microwave Reflection by Uniform Dense Plasmas

Convenient formulas are deduced, which relate electron densities and collision frequencies of uniform dense plasmas to two standing wave signals of a probing microwave reflected at a plane boundary of the plasma. In an experiment with a uniform afterglow plasma produced in a waveguide, the electron density from ${\text{2×10}}^{13}\hspace{0.17em}{\mathrm{cm}}^{\text{−3}}$ to ${\text{3×10}}^{11}\hspace{0.17em}{\mathrm{cm}}^{\text{−3}}$ is measured with reasonable value of the collision frequency by using a X-band microwave. The technique provides a mean for detecting an electron density as high as ${\text{1×10}}^{16}\hspace{0.17em}{\mathrm{cm}}^{\text{−3}}$ with the X-band microwave.