Several experiments on frequency shifting were done by Doctor Mark Rader in his thesis work under the supervision of Professor Igor Alexeff. Considering Mark Rader's work in more detail, the first experiment involved the use of a Bostick gun. Microwaves from a high-frequency, steady-state transmitter are injected through a Lucite window into an evacuated glass tube approximately 1m long. The microwaves reflected from a rapidly moving plasma jet from a Bostick gun are collected in the original transmitting waveguide, are redirected by a directional coupler, and are sent to a spectrum analyzer. Assuming that the wavelength is unchanged due to geometrical considerations, the frequency is upshifted by the increasing phase velocity in the plasma. To obtain the rise time for the plasma frequency, two sets of measurements were made. First, the peak plasma density was measured by a Langmuir probe technique. Second, the time resolved discharge current was measured using a fast current transformer in the discharge current feed.