Abstract. When thermal conductivity and diffusivity are measured with the hot disk thermal constants analyser, hot disk sensors or G-probes of different designs are used. The design of these sensors can be described as a double spiral etched out of a 10 mm thick metal foil sand- wiched between two thin insulating sheets of an electrically insulating material. So far mostly nickel and in a few instances platinum foil have been used as the `sensing' material. For experiments from 30 K up to about 450 K the polyimide Kapton with a thickness of 25 mm has been used as insulating material while for temperatures beyond 450 K and up to about 1200 K a 100 mm thick mica material is used. Attempts are presently being made also to use other insulating materials, which might further increase the temperature range of the sensors. Beside work on the further development of the sensors, work is going on to extend the appli- cation of this experimental technique to cover new experimental situations. Presently, some options in addition to the standard system can be utilised. These options include possibilities to measure the thermal transport properties of anisotropic bulk materials, thin insulting sheets of low conducting materials, and slabs of material with medium to high thermal conductivity. In addition there is a facility to measure the specific heat capacity of different materials directly. When the standard experimental technique is applied, the usual experimental arrangement is to place one piece of the sample material on either side of the sensor. However, attempts have recently been made to cover one side of the sensor with a material with known thermal properties and then place the material with unknown properties in contact with the other side of the probe. 1 Introduction Thermal conductivity and thermal diffusivity are the two thermal transport properties that are most commonly determined by a number of different experimental methods. It is usual to discriminate between the experimental techniques by referring to the temper- ature recordings and how these are being performed. When an experimental method is based on the recording of time independent temperatures, it is referred to as a steady state method and when time varying temperatures are recorded, it is called a transient method. The steady state methods have the advantage of comparatively easy temperature recordings, but in some cases the time to reach constant temperature in the selected measuring points can be considerable. Care must also be taken to measure and control the very heat flow that is creating the temperature gradients in the sample under investi- gation. When transient methods are used it is imperative to record the time varying temperatures carefully to obtain good results. In these cases it is on the other hand Recent developments and applications of the hot disk thermal constants analyser for measuring thermal transport properties of solids High Temperatures ^ High Pressures, 2000, volume 32, pages 47 ^ 51 15 ECTP Proceedings pages 75 ^ 79 Mattias Gustavsson Department of Thermo and Fluid Dynamics, Chalmers Institute of Technology, SE-412 96 Gothen- burg, Sweden Johan S Gustavsson Department of Microelectronics, Chalmers Institute of Technology, SE-412 96 Gothenburg, Sweden Silas E Gustafsson Department of Physics, Chalmers Institute of Technology, SE-412 96 Gothenburg, Sweden; fax: +46 31 772 3333; email: Silas.Gustafsson@adm.gu.se Lars Ha«lldahl Hot Disk Inc., Sturegatan 1, SE-753 14 Uppsala, Sweden Presented at the 15th European Conference on Thermophysical Properties, Wu« rzburg, Germany, 5 ^ 9 September 1999 DOI:10.1068/htwu259