Effects of misaligning the probe beam and magnetic field in Doppler backscattering measurements

Effects of misaligning the probe beam and magnetic field in Doppler backscattering measurements

Effects of misaligning the probe beam and magnetic field in Doppler backscattering measurements 150 150 UKAEA Opendata
UKAEA-CCFE-CP(19)18

Effects of misaligning the probe beam and magnetic field in Doppler backscattering measurements

The Doppler Backscattering (DBS) microwave diagnostic enables the non-perturbative characterisation of density fluctuations and flows, both at the edge and the core of the plasma. The large magnetic pitch angle (up to 35 degrees, compared to 15 degrees in standard tokamaks like JET) and the time-varying magnetic equilibrium make the use of DBS in spherical tokamaks challenging. Due to spatial variation, it is not possible to simultaneously achieve alignment between the probe beam and electric field for all launch frequencies. This misalignment, which affects the backscattered signal, can be empirically optimised with 2D beam steering [1].

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Conference:
45th European Physical Society Conference on Plasma Physics (EPS), Prague, 2-6 July 2018
Published date:
07/10/2018