Multichord laser interferometer for the magnetized target fusion program's field reverse configuration

Summary form only given. AFRL's Directed Energy Directorate has built a multichord 0.633 pm laser interferometer to diagnose the magnetically confined plasma of a Field Reverse Configuration (FRC) being developed for LANL and AFRL's collaborative Magnetized Target Fusion (MTF) program. The FRC is intended for subsequent compression to near thermonuclear fusion conditions by AFRL`s Shiva Star capacitor bank. The interferometer is ultimately designed to measure `the free electron density integral along eight chords of the nominally axisymmetric uncompressed FRC vs. time. This would permit Abel inversion to determine the density profile time history. The optics for only two chords, however, are installed as of abstract submission to assess design details. The instrument is installed and on-line on the FRC system presently at LAN. The interferometer's reference beam is split off using a Bragg cell driven by an 80 MHz piezoelectric. This gives the reference beam an 80 MHz higher optical frequency than the probe beam, permitting quadrature mixing of the interference signal at a convenient RF frequency. The prohe beam must traverse the walls of a 10 cm diameter quartz tube, which contains the FRC.