Electrodeless Investigation of Conductivity of Liquid in Capillaries with due Regard for Skin Effect

Abstract

Processes occurring in the setup for contactless measurement of conductivity of liquids have been considered. The experimental study of the relationship of the oscillating circuit Q-factor as a function of the specific resistance of liquid was performed using the electrode and electrodeless methods of measurements. Frequency relationships of additional attenuation d in the oscillating circuit caused by the presence of liquid with specific resistance ρ in inductively coupled capillary solenoid were investigated in the frequency range 2.2–8.8 MHz. It was shown that the impact of skin effect was significant for the considered values of ρ and the additional attenuation was described by formula d = – a 0 ( f ) + a 1 ( f )ρ –1/2 , where function a 1 ( f ) is proportional to f 3/2 , while function a 0 ( f ) is proportional to f 2 . Owing to different frequency dependences of functions a 1 ( f ) and a 0 ( f ), the frequency relationship of the relative depth of skin layer in liquid electrolyte was obtained in explicit form: h / r cp = A ( f )ρ 1/2 = af 1/2 ρ 1/2 , where a is the constant that does not depend on frequency and specific resistance of liquid.