A scanning facility for studying the thermoelectric behaviour of the metals used in elemental thermocouples (Au, Pt and Pd) is described. The facility effectively measured changes in Seebeck coefficient along a 560 mm length of each of three wires, relative to a fourth, by moving them through a 50 mm long, EMF-producing zone into a uniform-temperature region at 250 °C. The uniform region was stable to within 0.7 mK and EMF measurements were made to 10 nV (equivalent to about 1 mK). Accordingly, the facility is able to detect changes of ~10 ppm in Seebeck coefficient. The precautions necessary to work at this accuracy are detailed and preliminary data on the changes that occur at temperatures up to 1000 °C are reported. For example, the measured Seebeck coefficient of Pd decreased at temperatures in the range 550 to 850 °C, a change opposite in sign to that previously reported.

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Spectrally resolved measurements of Thomson scattering were made in a freely burning arc in argon at a pressure of 1 atm. The radial and axial profiles in electron temperature and number density exhibited extensive regions of departure from local thermodynamic equilibrium, so confirming the findings of Snyder et al in E 48 4124 - 7, 1993. Electron temperatures at least 4000 K above those of the gas were found. Asymmetry in the Thomson electron feature was found and shown to depend on which segment of the laser-profile scattering data was sourced. This arises from an asymmetry in the arc - laser interaction. Also described is a simple technique for accurately defining the position of the cathode tip once an arc has been ignited.