Turbulence wave number spectra reconstruction from radial correlation reflectometry data at Tore Supra and FT-2 tokamaks N. Kosolapova1,2,4, A. Altukhov1,4, A. Gurchenko1,4, E. Gusakov1,4, S. Heuraux2, R. Sabot3, F. Clairet3 1Ioffe Physical-Technical Institute of the Russian Academy of Sciences, Saint-Petersburg, Russia; 2Institut Jean Lamour, 7198 UMR CNRS, Nancy, France 3CEA, IRFM, F-13108, Saint Paul Les Durance, France; 4Saint-Petersburg State Polytechnical University, RLPAT, Saint-Petersburg, Russia Scope In this work we study plasma turbulence properties in a tokamak using radial correlation reflectometry (RCR). We aim to reconstruct the turbulence radial wave number spectrum, radial correlation length and turbulence spatial cross correlation function (CCF) from RCR measurements. This poster shows the preliminary results obtained at Tore Supra and FT-2 tokamaks. Tore Supra We have held RCR measurements using D-band (110-150 GHz) X-mode reflectometer in equatorial plane from low field side of the Tore Supra tokamak (R=2.25m, a=0.72m). Plasma density profile, shot #47669 (t=7s, Bt=3.8T, Ip=0.9MA, Te=2.3keV ) : FT-2 We present results of two RCR measurements held from the high field side of the FT-2 tokamak (R=50cm, a=8cm), . I. O-mode probing in Ka-band (27-40 GHz) in equatorial plane of the torus (Bt=2.1T, Ip=19kA, Te=200eV). Plasma density profile (t=32ms) : Conclusions We have estimated plasma turbulence parameters at large Tore Supra and small FT-2 tokamaks. These RCR experiments are preliminary and allow us to determine the experimental parameters for future attempts. RCR measurement in both equatorial plane of the tokamak and with a small shift give information on turbulence spectrum behavior and the scale of correlation length. Theoretical approach has been developed for O-mode probing of linear profile and tested in case of close to experimental profile [3] therefore can be applied for X-mode probing presented here. Equidistant spatial probing step is preferable to exponentially growing one which introduces difficulties into fast Fourier transform of the RCR CCF. RCR diagnostic provides more precise measurements for smaller values of wavenumbers than e.g. Doppler reflectometry. reflectometer HFS LFS Introduction Drift wave micro-turbulence is considered nowadays to be the main source of anomalous transport of heat and particles in magnetic fusion devices [1]. RCR is a microwave scattering technique for measuring the properties of electron density fluctuations in tokamaks [2]. Principle of RCR : Correlation between RCR signals : reflectometer HFS LFS Plasma density evolution in time, r/a=0.31 : Experimental RCR CCF : Spectrum reconstruction : n(r) - reference frequency - sweeping frequency Future plans We plan to study micro turbulence on JET machine in case of H-mode flat plasma density profiles and L-mode profiles knowing the required experimental parameters from simulations and previous experiments. Simulations of the RCR experiments are planned for typical ITER plasma density profiles in various regimes. - distance between cut offs - signal from plasma at reference frequency - signal from plasma at sweeping frequency r Number of points within a window : II. X-mode probing in V-band (50-75 GHz), antenna set shifted out of equatorial plane by 15mm. Plasma density profile (t=32ms) : - averaging samples - turbulence frequency resolution - probing frequencies 63 GHz 57GHz reflectometer Theoretical background Signal RCR CCF and turbulence CCF (1D simulations in Born approximation [3]) : - turbulence correlation length; - signal correlation length Relation between radial wave number spectrum and RCR CCF for linear plasma density profile [4] : - fluctuation wave number; - conjugate error function. Numerically reconstructed radial wave number spectrum [3]. Synthetic Gaussian spectrum: where References [1] B. Carreras, IEEE Trans. Plasma Sci. 24 (1997) 1281 [2] N. Bretz, Physical Fluids B4(8) (1992) 2414 [3] N. Kosolapova et al., Plasma Phys. Control. Fusion 54 (2012) 035008 [4] E. Gusakov, N. Kosolapova, Plasma Phys. Control. Fusion 53 (2011) 045012 [5] L. Vermare et al., C R Physique (2011) 12 115-122 [6] A. Altukhov et al., 39th EPS Conf. on Plasma Physics, Stockholm (2012) HFS LFS Turbulence radial wave number spectrum reconstruction : Doppler shift : Experimental CCF coherence : Turbulence spectrum : Contacts Natalia Kosolapova email : N.Kosolapova@mail.ioffe.ru Example of wavenumber spectrum measured on Tore Supra, Doppler reflectometry, shot #45511 [5]. Acknowledgements This work is partly supported by Centre-of-Excellence grant 047.018.002, RF government grant 11.G34.31.0041 and RFBR grants 11-02-00561 and 12-02-00515, by the Saint-Petersburg Government, the French Government and Carnot ICEEL program, Russian Government Grant according to Ordinance No. 220 under Agreement No. 11.G34.31.0041 with Ministry of Education and Science of Russia. Turbulence CCF, ELMFIRE fullwave modeling [6] : Turbulence CCF reconstruction : Radial correlation length : Turbulence CCF : shot #47669 at r/a=0.31 shots #47680-47686 at 0.3<r/a<0.8 on Tore Supra Radial correlation length : at r/a=0.56 on FT-2