Results from a double Li-beam technique for simultaneous measurement of the radial and poloidal components of electron density fluctuations by two thermal beams

Huber, A.; Schweer, B.; Samm, U.; Mertens, Ph.

doi:10.1088/0741-3335/47/3/002

Journal Article

PreJuSER-32094

Results from a double Li-beam technique for simultaneous measurement of the radial and poloidal components of electron density fluctuations by two thermal beams

Huber, A.FZJ* ; Samm, U.FZJ* ; Schweer, B.FZJ* ; Mertens, P.FZJ*

2005
IOP Publ. Bristol

Plasma physics and controlled fusion 47, 409 - 440 (2005) [10.1088/0741-3335/47/3/002]

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Please use a persistent id in citations: http://hdl.handle.net/2128/1801 doi:10.1088/0741-3335/47/3/002

Abstract: Determination of both the radial and poloidal components of electron density fluctuation parameters in a tokamak edge plasma was achieved by operation of two narrow Li-beams (FWHM approximate to 10 mm at a distance of 100 mm from the source), which were separated by 50 mm. Beams of thermal lithium atoms were generated using a newly developed oven, which provides a long operation time and a high reliability. The lithium atoms, with a mean velocity of approximate to 1.7km s(-l), were injected radially into the plasma edge, where they were excited and ionized by the plasma. The line radiation (resonance transition 2s-2p, lambda = 670.8nm) of the excited atoms was observed, which enables determination of the electron density profiles. The measurements are performed with high temporal (At similar or equal to 2 mu s) and spatial (Delta(r) similar or equal to 1 mm in the radial and Delta(p) similar or equal to 10mm in the poloidal direction) resolution, thus also allowing determination of the fluctuations. This new diagnostic permits studies of both radial and poloidal fluctuation parameters like the correlation length, wavenumber, frequency spectrum, propagation velocity and lifetime. The method can be applied continuously over long discharges without disturbing the plasma.Some figures in this article are in colour only in the electronic version).

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