High-speed observation of the piston effect near the gas-liquid critical point
2006; American Physical Society; Volume: 74; Issue: 1 Linguagem: Inglês
10.1103/physreve.74.010101
ISSN1550-2376
AutoresYuichi Miura, Shoichi Yoshihara, Mitsuru Ohnishi, Katsuya Honda, Masaaki Matsumoto, Jun Kawai, Masamichi Ishikawa, Hiroto Kobayashi, Akira Ōnuki,
Tópico(s)Mechanical and Optical Resonators
ResumoWe investigated adiabatic changes in a near-critical fluid on acoustic time scales using an ultrasensitive interferometer. A sound emitted by very weak continuous heating caused a stepwise adiabatic change at its front with a density change of order ${10}^{\ensuremath{-}7}\phantom{\rule{0.3em}{0ex}}\mathrm{g}∕{\mathrm{cm}}^{3}$ and a temperature change of order ${10}^{\ensuremath{-}5}\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Very small heat inputs at a heater produced short acoustic pulses with width of order $10\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}$, which were broadened as they moved through the cell and interacted with the boundaries. The pulse broadening became enhanced near the critical point. We also examined theoretically how sounds are emitted from a heater and how applied heat is transformed into mechanical work. Our predictions agree well with our data.
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