Basal glide of dislocations in ice observed by synchrotron radiation topography

In-situ observation of basal glide of dislocations in ice has been carried out using synchrotron radiation topography (SRT) between -0.2 and -18.4 deg rees C under uniaxial compressions. The maximum shear stress on the basal p lane was chosen to be 0.060 MPa in order to observe the glide motion of dis locations under low stresses. The radii of curvature of dislocation bends i n the steady state are measured on a scale of SRT subject to the low-stress conditions. From the radius of curvature and dislocation velocity, the con centration of thermal kinks on the dislocation and the kink velocity are se parately estimated. The migration free energy estimated from the kink veloc ity agrees well with the free energy of the Debye relaxation time that is g enerally accepted.