A Doppler backscattering system for measuring fluctuations and their perpendicular velocity on tore supra
Backscattering of a microwave beam launched in oblique incidence makes possible measurement of density fluctuations close to the cut-off with a selected wavenumber vector k = -2 vector k(i), where vector k(i)is the beam wavevector at the reflection layer. On the system installed on Tore Supra in 2003, the incidence of the gaussian beam is controlled thanks to a tiltable monostatic antenna. The microwave part of the system is based on a fluctuation reflectometer scheme with heterodyne detection, and the choice of a V band (50 - 75 GHz) microwave source and O mode polarization is appropriate for typical ITB enhanced plasma regimes on Tore Supra (n(0) = 3 to 7 10 m[-3]). Both the scattering wavenumber k and the scattering localization r/a can be changed during a shot, owing to the stoppable probing frequency and the motorized antenna (tilt angle 0 to 10 degrees). The wavenumber range k is 4 and 15 cm[-1], with a wavenumber resolution around 2 cm[-1], and the localization from r/a approximately 0.3 to 0.85. The Doppler effect allows to measure the perpendicular velocity profile for the same position range. First experiments confirm the diagnostic capabilities.
Bibliographic Reference: An oral paper given at: 15th Topical Conference on High-Temperature Plasma Diagnostics Organised by: General Atomics, San Diego (US) Held at: Hyatt Regency Islandia Hotel, San Diego(US)
Availability: Available from Association EURATOM-CEA, Departement de Recherches sur la Fusion Controlee, CEA Cadarache, F-13108 St Paul-Lez-Durance, France Tel: (+33) 4 42 25 70 01; Fax: (+33) 4 42 25 64 21 E-mail: firstname.lastname@example.org
Record Number: 200417523 / Last updated on: 2004-06-11
Original language: en
Available languages: en