Showing papers by "Mehdi Sohrabi published in 1987"

On the discovery of some phenomena in electrochemical etching of polymeric dosimeters

Abstract: Although electrochemical etching (ECE) of polymeric dosimeters has been advancing for over a decade, some phenomena such as “dielectric loss”, “electro-osmosis”, “dielectrophoresis” and “electrostriction” have been recently discovered and proved to exist in ECE ehich are reported and discussed in this paper. The “dielectric loss” mechanisms lead to an internal heating effect which heats up the etchant effectively with a rate per unit foil volume proportional to E 2 , f , and polymer loss index (ϵ′ tan δ). Thus foil effective diameter, etchant volume, and the chamber's external insulation were introduced as new important parameters in ECE especially at high applied field conditions. The combined effects of “electro-osmotic pressure” and “dielectrophoretic forces” are discussed to cause “water tree” microstructure of tracks in CR-39 with a “water bubble” at the center which has a temporary nature, and “electrostriction” seems to cause dimensional changes of some foils under ECE. In this paper, the existence of the above phenomena in ECE and their impacts on the ECE parameters as well as neutron dosimetry responses and track shapes in polycarbonate and CR-39 neutron dosimeters under different applied field conditions are demonstrated and discussed.