PCI beam paths on (a) Alcator C-Mod and (b) DIII–D are shown shaded on the machine cross section.
Miller coordinate system for a GYRO simulation of a C-Mod discharge. Flux surfaces are spaced by 0.05 in . Spacing of coordinates is .
A reconstruction of fluctuating electron density for a typical GYRO run. This is performed on a simple grid for visualization purposes. The vertical lines represent the PCI beam path.
The spectrum from a SPCI calculation applied to a GYRO simulation of a C-Mod discharge. (a) No Doppler shift added. (b) Rotation frequency is applied, equivalent to a perpendicular plasma flow velocity of approximately at the measurement location. Dashed line represents a phase velocity of 4 km/s.
Experimental PCI spectra from two similar plasmas with either the responsivity localized in either the (a) lower or (b) upper portion of the tokamak. The SPCI spectra are shown limited to (c) and (d) .
The broadband turbulence at high frequency of the (a) SPCI and (b) experimental PCI with the spatial localization filter selecting for the upper plasma. Dashed line represents a phase velocity of 4 km/s. Note suppressed zero on frequency scale.
Frequency spectra of the experimental PCI (solid line), SPCI including Doppler shift (dash-dot line), and SPCI with no Doppler shift (dashed line). Peak in experimental spectrum at 140 kHz is due to the QC mode. Increasing the number of low- modes in the GYRO simulation would smooth out the SPCI spectrum at low but not change the overall power (Ref. 27).
2D power spectrum at calculated from GYRO simulation data. Fluctuating density sampled at , on a grid with a spacing of 2.2 mm.
Article metrics loading...
Full text loading...