title: Multi-channel Doppler backscattering measurements in the C-2 field reversed configuration.
abstract: A versatile heterodyne Doppler Backscattering (DBS) system is used to measure density fluctuation levels (in the wavenumber range kρs ≤ 50), and the toroidal E × B flow velocity in the C-2 Field-Reversed Configuration (FRC). Six tunable frequencies in three waveguide bands (26 GHz ≤ f ≤ 90 GHz) are launched using monostatic beam optics, via a quasi-optical beam combiner/polarizer and an adjustable parabolic focusing mirror (inside the vacuum enclosure) achieving Gaussian beam spot sizes of 3-5.5 cm at the X/O-mode cutoff. The DBS system covers plasma densities of 0.8 × 10(13) ≤ ne ≤ 1 × 10(14) cm(-3), and provides access to the FRC core (up to the field null) and across the FRC separatrix into the scrape-off layer plasma.
authors.affiliation: Department of Physics & Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA.
authors.forename: L
authors.initials: L
authors.lastname: Schmitz
authors.affiliation: Department of Physics & Astronomy, University of California, Irvine, Irvine, California 92697, USA.
authors.forename: E
authors.initials: E
authors.lastname: Ruskov
authors.affiliation: Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688, USA.
authors.forename: B H
authors.initials: BH
authors.lastname: Deng
authors.affiliation: Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688, USA.
authors.forename: H
authors.initials: H
authors.lastname: Gota
authors.affiliation: Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688, USA.
authors.forename: D
authors.initials: D
authors.lastname: Gupta
authors.affiliation: Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688, USA.
authors.forename: M
authors.initials: M
authors.lastname: Tuszewski
authors.affiliation: Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688, USA.
authors.forename: J
authors.initials: J
authors.lastname: Douglass
authors.affiliation: Department of Physics & Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA.
authors.forename: W A
authors.initials: WA
authors.lastname: Peebles
authors.affiliation: Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688, USA.
authors.forename: M
authors.initials: M
authors.lastname: Binderbauer
authors.affiliation: Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688, USA.
authors.forename: T
authors.initials: T
authors.lastname: Tajima