Techniques for accurate resistance measurement in the transient short-hot-wire method applied to high thermal-diffusivity gas

The accuracy of high-speed transient resistance measurements is an important issue particularly for measuring the thermal conductivity of high thermal-diffusivity (low-density) gases. This is because the hot-wire temperature rise against the logarithm of time is non-linear and can approach a steady state within the typical measurement time of 1 s. Two types of voltmeters are compared for use in the transient short-hot-wire method. Details of suitable procedures for taking accurate transient resistance measurements with either a two-channel high-speed analog/digital converter or a pair of integrating digital multimeters are presented.