title: Multichannel microwave interferometer for the levitated dipole experiment.
abstract: A four-channel microwave interferometer (center frequency: 60 GHz) has been constructed to measure plasma density profiles in the levitated dipole experiment (LDX). The LDX interferometer has a unique design owing to the unique geometry of LDX. The main design features of the interferometer are: (1) the transmitted beam traverses the plasma entirely in O-mode; (2) the interferometer is a heterodyne system employing two free-running oscillators; (3) four signals of data are received from just on transmitted beam; (4) phase shifts are detected in quadrature. Calibration tests demonstrate that the interferometer measures phase shifts with an uncertainty of approximately 5 degrees . Plasma densities in LDX corresponding to phase shifts of up to 5pi are routinely and successfully measured.
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 USA.
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Boxer
authors.forename: Darren T
authors.initials: DT
authors.lastname: Garnier
authors.forename: Michael E
authors.initials: ME
authors.lastname: Mauel