XXXIII International Conference on Plasma Physics and CF, February 13 – 17, 2006, Zvenigorod
SPECTRA OF CROSS-POLARIZATION UPPER HYBRID RESONANCE SCATTERING
IN THE FT-2 TOKAMAK
A.B. Altukhov, L.A. Esipov, A.D. Gurchenko, E.Z. Gusakov, A.Yu. Stepanov
Ioffe Institute, St.-Petersburg, RF, e-mail: aleksey.gurchenko@mail.ioffe.ru
The cross-polarization scattering (CPS) diagnostics provides a unique possibility for spectra
measuring of small-scale magnetic turbulence, disturbing the system of nested magnetic surfaces
and leading to huge energy losses along the field lines. Intensive density fluctuations do not
contribute to the CPS signal in the 1D experimental geometry utilizing microwave probing
perpendicular to the tokamak magnetic field. At the same time the scattering off relatively low
magnetic fluctuations (B) can change the extraordinary (Xi ) probing wave polarization resulting in
ordinary wave appearance [1]. The CPS effect was used earlier for diagnostic development on Tore
Supra [2] and FT-1 [3] tokamaks. Pilot experiment with CPS signal originating in the upper hybrid
resonance (UHR) at the FT-2 tokamak was discussed recently in [4].
The correlation measurements of the UHR CPS signals at the FT-2 tokamak (R = 55 cm,
a  8 cm), where a double antenna set (X-mode for equatorial plane: ya = 0 mm; O-mode for
ya = 15 mm) was installed at the low magnetic field side in the same poloidal cross-section, but
opposite to the vertically movable focusing X-mode antennae, are reported in the present paper.
It is shown that the pronounced spectral component of the CPS signal with frequencies
f < 1 MHz possesses wave length in the interval 0.02-0.06 cm and thus can be only produced by
CPS off small-scale fluctuations in the UHR.
Supports of RFBR grants 05-02-16569, HIII-2159.2003.2, INTAS grant 01-2056, NWO-RFBR
grant 047.016.015 are acknowledged.
Reference.
[1]. T. Lehner, D. Gresillon, X.L. Zou et al. Proc. 12 EPS Conf. on CFPP, Budapest, 1985, V.II,
p.644.
[2]. X.L. Zou, L. Colas, M. Paume et al., Phys. Review Lett., 1995, V.75, p.1090.
[3]. D.G. Bulyiginskiy, A.D. Gurchenko, E.Z. Gusakov et al., Phys. Plasmas, 2001, V.8, p.2224.
[4]. A.D. Gurchenko, E.Z. Gusakov et al., Proc. 27 EPS Conf. on CFPP, Budapest, 2000, V.24B,
p.416.
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