Dislocation damping and charge effects in irradiated bent sodium chloride crystals

Abstract

An ultrasonic regenerative system operating at 84 kHz is used to measure changes in NaCl single crystals during neutron irradiation. A theoretical analysis is presented based on a simplified vibrating-string model which includes dislocation charge effects. Elastic modulus changes are found to be entirely due to changes in average loop length. Damping changes are found to depend not only on loop length but also on interactions between the charged core region and the surrounding charge-cloud region. The values of the damping factor, B, and dislocation charge, q, both vary during irradiation for pure crystals.