Experimental Investigation of Thermomagnetic Torque in Hydrogen

An investigation of the thermomagnetic torque, or Scott effect, has been carried out in hydrogen at several parahydrogen concentrations. Measurements were made with a sensitive torsion pendulum over a range of temperatures from 80 to 380 K with pressures from 0.035 to 1.50 Torr. The measured torques are dependent on magnetic field and on pressure, in general agreement with the phenomenological theory of Levi and Beenakker. At room temperature, pure parahydrogen produces a much larger torque than orthohydrogen. At all para concentrations studied, the maximum of torque per unit temperature gradient multiplied by pressure, as a function of field divided by pressure, occurs at $\frac{H}{P}=50\mathrm{}$ Oe/Torr. In pure parahydrogen, the torque was found to approach zero as the temperature fell below 100 K.