ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
A time–frequency analysis of plasma turbulence is performed for the GAMMA10 tandem mirror plasma. The method is based on the decomposition of the reflectometer signal into a set of wavelets. Excellent resolution in the time–frequency domain, inherent to wavelet analysis, allowed us to observe fast changes in the instantaneous spectra of fluctuations, which would be averaged out if treated using conventional Fourier analysis. In order to estimate the propagation velocity of turbulent fluctuations, a wavelet cross-correlation function was calculated. Comparison of wavelet spectra, corresponding to different reflectometer channels, demonstrates the existence of short-time flashes of fluctuation intensity, as well as elongation of low-frequency disturbances along the magnetic field lines and their rotation in the E×B direction. Plasma fluctuations in the Alfvén range of frequencies sometimes propagate from the center towards the magnetic plugs with velocities close to 1000 km/s. In general, the wavelet spectra of plasma turbulence in the Alfvén range of frequencies, viewed by means of the microwave reflectometer, appear to be much more irregular than the corresponding spectra of magnetic field fluctuations obtained using magnetic probes. © 1999 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1149493
