TITLE

Vertical localization of phase contrast imaging diagnostic in Alcator C-Mod

AUTHOR(S)
Lin, L.; Edlund, E. M.; Porkolab, M.; Lin, Y.; Wukitch, S. J.
PUB. DATE
October 2006
SOURCE
Review of Scientific Instruments;Oct2006, Vol. 77 Issue 10, p10E918
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Phase contrast imaging (PCI) diagnostic has been used to study mode conversion physics of ion cyclotron range of frequency waves [E. Nelson-Melby et al., Phys. Rev. Lett. 90, 155004 (2003)], plasma turbulence [A. Mazurenko et al., Phys. Rev. Lett. 89, 225004 (2002); N. Basse et al., Phys. Plasmas 12, 052512 (2005)], and Alfvén Cascades [M. Porkolab et al., IEEE Trans. Plasma Sci. 34, 229 (2006)] in Alcator C-Mod. The C-Mod PCI system measures line integrated electron density fluctuations along 32 vertical chords with a sampling frequency of 10 MHz and wavenumber resolution up to 30 cm-1. Although PCI normally lacks localization along the chords, the vertical variation of the magnetic field pitch angle allows for localized measurements for large k⊥ fluctuations. A system consisting of a partially masked phase plate on a rotatable stage has been installed and quasicoherent modes with wave number ∼5 cm-1 associated with the enhanced DαH mode at the top and bottom of the plasma have been differentiated. In future experiments, for k∼30 cm-1, a spatial resolution of r/a∼0.3 can be achieved under ideal conditions.
ACCESSION #
23073189

 

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