High resolution Thomson scattering temperature profiles at the TJ-II stella
rator are subjected to spectral analysis. The obtained k spectrum is very r
obust in shape. While its amplitude has been shown previously to scale inve
rsely with the collisionality, here it is found that its shape is independe
nt of plasma configuration (magnetic well, iota), global plasma parameters
(temperature, density) and radial position (centre, edge). The shape is als
o found to be very similar to that of k spectra obtained with Langmuir prob
es in the edge of TJ-II and of k spectra obtained using other techniques in
other devices. The spectral shape is characterized by a 'knee' at k = 500-
1000 m(-1) and a steep decay at large K. Self-similarity analysis reveals t
he existence of a high degree of self-organization dominated by structures
of around 2.5 cm in size.