アルメル線の熱起電力の圧力効果

抄録

Pressure dependence of the absolute thermal emf of alumel has been determined by means of an opposed anvil type high pressure device, under a temperature difference of 100°C between top and bottom anvils at pressures up to 130 kbar. Since, with a solid-pressure apparatus of the present configuration, large shear stresses and plastic deformations are expected to develop in the pressure medium, correction has to be made for a plastic strain effect on the thermal emf. The thermal emf due to this effect increases with a rate of 0.43μV/100°C/kbar up to 25 kbar, beyond which pressure it remains constant at lOμV/100°C. This tendency was confirmed by tension and compression tests on alumel wires. The thermal emf is increased by pressure taking a positive slope of 1.2μV/100°C/kbar with negative curvature and amounts to 88μV/100°C at130 kbar. An error due to the nonuniform distributions of both temperature and pressure in the pressure cell is estimated by Hanneman's method.