Features of a low frequency ion mode were observed together with the e
lectron drift wave type fluctuations by a Langmuir probe array in the
bulk plasma inside the velocity shear layer in the KT-5C tokamak. The
measured ion mode wavenumber, scaling of the ion mode with chord-avera
ged density, and the estimated eta i value suggest that the observed i
on mode may be the theoretically predicted eta i mode driven by ion te
mperature gradient.