Fast synthetic X-mode Doppler reflectometry diagnostics for the full-f global gyrokinetic modeling of the FT-2 tokamak

Abstract

Irzak, M. A.; Niskala, P.; Esipov, L. A.; Kiviniemi, T. P.; Leerink, S. Fast synthetic X-mode Doppler reflectometry diagnostics for the full-f global gyrokinetic modeling of the FT-2 tokamak S. (2018). Fast synthetic X-mode Doppler reflectometry diagnostics for the full-f global gyrokinetic modeling of the FT-2 tokamak.

Influence of the probing wave phase modulation on the X-mode radial correlation Doppler reflectometry performance in the FT-2 tokamak

“…Not only are the velocities determined from the Doppler frequency shifts of both spectra close but also the spectral shapes look alike. The obtained agreement between the measured and computed DR spectra, 27 which are determined by the plasma flows, provides evidence in favor of correct modeling of plasma poloidal rotation and a correct reproduction of the radial electric field behavior in the FT-2 tokamak by the ELMFIRE code.…”

“…There are at least two possible reasons for the drastic difference between the experimental and synthetic RCDR cross-correlation functions. The first one is related to the GK code spatial grid limitations, leading to underestimation of the turbulence wavenumber spectrum width 27 and thus to overestimation of the density fluctuation two-point radial cross-correlation functions width. The dependence of the absolute value of the density fluctuation CCF on point separation is shown in Fig.…”

“…17,18 The development of a synthetic diagnostics that allows the computation of DR signals based on GK simulations is useful for both comprehensive interpreting of the experimental results and the code benchmarking. 17,[19][20][21][22][23][24][25][26] In the present paper, the linear version of the X-mode high magnetic field side (HFS) DR synthetic diagnostics developed recently 27 in the framework of the ELMFIRE global GK modeling of the FT-2 tokamak ohmic discharge is applied for the interpretation of the radial correlation Doppler reflectometry (RCDR) data obtained in Ref. 18.…”

Validation of full-f global gyrokinetic modeling results against the FT-2 tokamak Doppler reflectometry data using synthetic diagnostics

“…The fast synthetic X-mode DR diagnostic developed for this code [19] is based on the reciprocity theorem of electrodynamics [27], relating the high-frequency current in the plasma volume and the signal radiated by it and received by the antenna. The probing and BS wave propagation in the plasma not perturbed by turbulence is described in the fast synthetic diagnostic by the full-wave code WaveTOP2D [28].…”

“…In this paper two versions of the X-mode DR synthetic diagnostics are compared within the framework of the ELMFIRE global GK modeling of the FT-2 tokamak ohmic discharge [6]. The X-mode DR signal is computed both in the linear theory approximation using the reciprocity theorem, utilizing the probing wave field pattern provided by computation and taking into account the 2D plasma inhomogeneity effects [19], and by the full-wave code IPF-FD3D describing the probing and scattered wave propagation in turbulent plasma [20]. The temporal behavior of the DR signal frequency spectra and the dependence of its amplitude, frequency shift and shape on the probing antenna position are computed and compared to those measured in the experiment at the FT-2 tokamak.…”