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Earth, Planets and Space
Fig. 12 | Earth, Planets and Space

Fig. 12

From: A procedure for stable electrical measurements on a rock sample against high contact resistance as a prerequisite for electrical tomography

Fig. 12

Photograph and schematic diagram of the measurement set-up with an array of electrodes. a Cylindrical rock sample (52 mm diameter and 100 mm length) overlaid with the dimensions r, θ, and z defining its coordinate axes. Electrodes were attached to the cylindrical surface, and wires attached to electrodes provided a connection for measuring instruments. b Measurement scheme. z and θ are coordinates defined in Fig. 10a. The dotted square is a constant direct current source, RIN is input resistance, RV is insulation resistance between the negative terminal and chassis ground, HI labels positive terminals, and LO labels negative terminals. The direct current source (Model 6243, ADC; Saitama, Japan) injected a known constant current. An ammeter (Model 3458A, Keysight; Santa Rosa, California, US.) monitored the amount of injected current. Electrometers (Model 6514, Keithley; Cleveland, Ohio, USA) with RIN = 200 TΩ acted as the voltmeters

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