A straightforward DC-reversal method for the Thomson coefficient measurement

DC reversal is a widely used technique for precise voltage measurement to remove DC offsets from the measurement signals. Herein, we propose a straightforward method using a DC reversal for the thermoelectric Thomson effect measurements. The proposed method allows the determination of Thomson coefficient from readily measurable quantities, that is, DC resistance, current, and the temperature changes caused by the Joule and Thomson effects, thereby removing the requirement of information on thermal conductivity and geometric values, which are required in a traditional DC-reversal method. Furthermore, this DC-based approach avoids typical complications experienced in recently developed AC-based methods, such as the absence of an AC current source or lock-in amplifier. The experimental results show that the Thomson coefficient of a fine Pt wire measured using the proposed method agrees well with a previously reported reference measurement with the expanded relative uncertainty of 6 %.