Abstract
During the Second German Spacelab Mission D2 (April 26 to May 6, 1993) the isochoric specific heatc v of SF6 was measured along the critical isochore under microgravity conditions with a newly developed scanning radiation calorimeter. This calorimeter provided the possibility to perform comparable heating and cooling runs with variable ramp rates since the spherical sample cell was heated and cooled only by radiation. During the experimental time of 220 h, 11 heating and cooling runs with different ramp rates were performed in a temperature range ofT–T c=±6 K. ApproachingT c by cooling from the homogeneous one-phase region avoided significant temperature and density gradients in the fluid, which would have distorted the integral measurement ofc v. The inhomogenities introduced by a finite ramp rate were greatly reduced by the fast dynamic temperature propagation (“critical speeding up”). Thec v data achieved with slow cooling runs are in remarkably good agreement with the theoretical prediction more than one order of magnitude closer to the critical point than anyc v measurements done so far. The preliminary value for the critical exponentα is 0.107±0.02, and for the amplitude ratio we obtainedA −/A +=1.94±0.07. In contrast to the cooling runs, the heating runs showed a strong hysteresis ofc v. A comparison to 1g measurements is provided.
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References
J. Straub and K. Nitsche,Fluid Phase Equil. 88:183 (1993).
K. Nitsche,Die isochore Wärmekapazität im kritischen Gebiet von SF 6 unter Erdschwere und reduzierter Schwere, Thesis (Technical University Munich, Munich, 1990).
K. Nitsche, J. Straub, and R. Lange,Scientific Report Aeronautics and Astronautics (BMFT, 1984).
H. Boukari, J. N. Shaumeyer, M. E. Briggs, and R. W. Gammon,Phys. Rev. A 41:2260 (1990).
B. Zappoli, D. Bailly, Y. Garrabos, B. LeNeindre, P. Guenon, and D. Beysens,Phys. Rev. A 41:2264 (1990).
J. Straub, L. Eicher, and A. Haupt,Int. J. Thermophys. 16:1051 (1995).
J. Straub, L. Eicher, and A. Haupt,Phys. Rev. E 51 (6) (1995).
A. Abbaci and J. V. Sengers, Technical Report No. BN 1111 (University of Maryland, College Park, 1990).
J. Straub, A. Haupt, and K. Nitsche,Fluid Phase Equil. 88:123 (1993).
. Michels, personal communication (1981).
J. C. Le Guillou and J. Zinn-Justin,Phys. Rev. B 21:3976 (1980).
D. Beysens, personal communications (1992).
R. Gammon, personal communications (1994).
A. Onuki, A. Ferell,Physica A 164:245 (1990).
J. Straub and L. Eicher, accepted for publication inPhys. Rev. Lett. (1995).
M. Moldover and R. Gammon,J. Chem. Phys. 80:528 (1984).
T. J. Edwards,Specific Heat Measurements Near the Critical Point of CO 2 Thesis (University of Western Australia, 1984).
E. Bloemen, J. Thoen, and W. Van Dael,J. Chem. Phys. 73:4628 (1980).
A. Aharony and P. C. Hohenberg,Phys. Rev. B 13:3081 (1976).
M. Barmatz, P. C. Hohenberg, and A. Kornblit,Phys. Rev. B 12:1947 (1975).
C. Bervillier,Phys. Rev. B 14:4964 (1976).
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Straub, J., Haupt, A. & Eicher, L. Measurements of the isochoric heatc v at the critical point of SF6 under microgravity: Results of the German Spacelab Mission D2. Int J Thermophys 16, 1033–1049 (1995). https://doi.org/10.1007/BF02081273
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DOI: https://doi.org/10.1007/BF02081273