Density Profile Measurements in LDX using Microwave Reflectometry

The levitated dipole experiment (LDX) has a sharply peaked, stationary plasma density profile as shown recently by measurements with a four-channel microwave interferometer. More precision in profile measurement is needed to fully explore the stability of high beta LDX plasmas. A 4-8 GHz O-mode scanning reflectometer is being implemented that will probe the entire LDX density profile (the density in LDX varies in the range of 2-8x10$^{17}$ m$^{-3})$. This will add to information obtained from the four channels of the interferometer array and will be the first time a continuous density profile measurement is achieved in a levitating dipole plasma. This is important because it is needed to confirm predictions of a 1/r$^{4}$ density profile obtained by Abel inversion of the interferometer data and to obtain the exact location of the peak density in LDX for the first time.