Author: team the HT-7 Sun P.J. Li Y.D. Li Q. Zhang W.Y. Zhang X.D. Cao G.M. Hu L.Q. Li J.
Publisher: IOP Publishing
ISSN: 1402-4896
Source: Physica Scripta, Vol.86, Iss.2, 2012-08, pp. : 25504-25510
Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.
Abstract
An electromagnetic wave coherent scattering system has poor longitudinal spatial localization. However, considering the spatial variation of magnetic field lines and the perpendicularity of the short-scale turbulence to these magnetic field lines, we may be able to obtain spatially localized turbulence measurements. In this paper, we first describe the method and simulation results for localized turbulence measurements by a &${rm{CO}}_{rm{2}}$ ; laser (&$lambda = {rm{10}}{rm{.6}},mu {rm{m}}$ ;) collective scattering diagnostic on the HT-7. Second, we study the performance of electron density fluctuations between channel 1 (&$alpha = - 5^{circ} ,$ ; &$k_{rm{1}} = {rm{15}},{rm{cm}}^{ - {rm{1}}}$ ;) and channel 2 (&$alpha = 0^{circ} ,$ ; &$k_{rm{2}} = {rm{15}},{rm{cm}}^{ - {rm{1}}}$ ;) during sawtooth activities. After a sawtooth crash, the signals of channel 1 change considerably and the signals of channel 2 remain nearly the same; cross-correlations between the two channels are very low (≍0.1). These experimental results verify that our &${rm{CO}}_{rm{2}}$ ; laser collective scattering diagnostic does have some spatial resolution on HT-7.