Measurements of thermal effusivity of a fine wire and contact resistance of a junction using a T type probe.

The thermal effusivity of a fine wire and the thermal contact resistance of a junction have been measured by a modified T type probe using a periodic heating method. The modified T type probe is made of a short periodic heated platinum wire and a test wire with one end contacting to the midpoint of the hot wire. Dimensionless expressions for the temperature responses of the hot wire with respect to the thermal effusivity of the test wire and the thermal contact resistance of the junction between the test wire and the hot wire were presented. A measurement system based on a flexible resolution A/D board and a LABVIEW-based virtual lock-in was setup. The probe was further verified by measuring four kinds of commercially available metallic wires at room temperature. The obtained thermal contact resistances were repeatable, with the calculated thicknesses of about 1 to 2 microm. The present method can further be applied to measure the thermal effusivity of nonconductive wires, and to analyze the thermal contact resistance of nano/microscale junction.