The viscosity of polyatomic gases in a magnetic field

Influence of a magnetic field on the viscosity of a dilute gas consisting of linear molecules

“…They used an experimental arrangement with an electromagnet that could be rotated to realize different orientations between the magnetic field and the flow. Measurements at three different orientations allowed them to evaluate −∆η 42 They were specifically generated to validate the correct functioning of the apparatus, and they agree with the data of Hulsman et al, 38,39 which were used as reference values. Therefore, these data sets are only partially used in our comparison.…”

“…This is the only viscomagnetic coefficient that has no contribution from the dominant jj polarization and is consequently expected to be much smaller than the other coefficients. The values of −∆η + 0 /η evaluated by Hulsman et al 39 at T = 293 K increase from zero at low B/P values to a plateau of 5 × 10 −5 at the highest magnetic field strengths measured, B/P = (2.8-7.0) × 10 −3 T/Pa. As the calculation performed by Hulsman et al 39 involved a subtraction of two large numbers, the reproducibility is low and the scatter of the quoted −∆η Figure 4 shows the calculated values and the experimental data of Hulsman et al 38 for the two transverse viscomagnetic coefficients, η 36 which are not included in Fig.…”

“…The 77.4 K measurements were performed in an apparatus with a much smaller vacuum jacket than was used for the measurements at higher temperatures, and the actual temperature was measured at the vacuum jacket rather than in the middle of the gas. Furthermore, Burgmans et al 40 have stated that it was "difficult to achieve a temperature stability good enough to successfully operate the apparatus below 77 K." Only Hulsman et al 39 performed measurements that allowed for a value of the coefficient −∆η + 0 /η to be calculated. This is the only viscomagnetic coefficient that has no contribution from the dominant jj polarization and is consequently expected to be much smaller than the other coefficients.…”

“…Korving followed this work with more extensive measurements 35 of two different longitudinal coefficients, −(∆η 36 This was followed by work of Hulsman and coworkers, 37,38 who measured both transverse viscomagnetic coefficients, η − 1 /η and η − 2 /η, at room temperature using an experimental setup with an adjustable magnet orientation, which allowed for the determination of both coefficients with lower uncertainty. Subsequently, Hulsman et al 37,39 reported a further set of measurements to evaluate the longitudinal coefficients at room temperature in the B/P range up to 0.007 T/Pa (9.5 kOe/Torr). They used an experimental arrangement with an electromagnet that could be rotated to realize different orientations between the magnetic field and the flow.…”

“…We have also included the experimental data of Korving et al 34 and the data calculated from the coefficients −∆η A similar underestimation at high B/P ratios of data generated by Korving using the same apparatus was observed for CH 4 . 6 Mazur et al 41 39 and we have included their high B/P data for the viscomagnetic coefficient −∆η Fig. 2.…”