DENSITY FLUCTUATION MEASUREMENT ON THE FT TOKAMAK BY SMALL ANGLE CO-2 LASER SCATTERING
The understanding of the loss mechanisms related to the anomalous transport in Tokamaks requires, among other things, the study of density fluctuations with wavelengths much smaller than the plasma minor radius, usually denoted as microinstabilities. Collective scattering of laser or microwave radiation is usually employed for such investigations. Drift waves are considered to be the favourite candidate for explaining the anomalous energy and particle diffusion: these modes have frequency of about 100 kHz and wavelength of a few millimeters for typical tokamak regimes. Many experiments have found a strong activity in this range, indicating also that the observed fluctuations are to be described as a turbulence rather than as a superposition of linear modes. In this paper the results are presented that waves obtained on FT (R=83 cm, a=20cm, B-T=40-80 kG, T-e=1 keV, n-e about 10**14 cm**-3) by a small angle CO-2 (10.6 mum) scattering experiment: measured fluctuations have an average relative level of 1-6%, wavelengths of 1-5 mm and frequency spectra extending up to few hundred kilohertz.
Bibliographic Reference: 12TH EUROPEAN CONFERENCE ON CONTROLLED FUSION AND PLASMA PHYSICS, BUDAPEST (HUNGARY), SEPT. 2-6, 1985 PP. 59-62 WRITE TO SERVIZIO STUDI E DOCUMENTAZIONE - ENEA, CENTRO RICERCHE ENERGIA FRASCATI, C.P. 65 - 00044 FRASCATI, ROMA (ITALY), MENTIONING REPORT RT
Record Number: 1989125048200 / Last updated on: 1987-07-01
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