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Dielectric spectroscopy and relaxation analysis of methane hydrate
Ryo Shirakashi, Kunihiko Kasahara, Satoru Miura, Kenichiro Tsuyuki and Daisuke Tajima
Dielectric spectrum of methane hydrate (MH; Type I) in a radio frequency range was measured at the thermal equilibrium region of ambient temperature and pressure. The developed measuring device allows the spectroscopy under the deep-sea environment where the pressure is high (5~10MPa) and the temperature is low (0~10 &Mac176;C). The measured spectrum showed Debye relaxation in the frequency range where the relaxation frequency of Ih-type pure ice exists. The activation energy of MHdi electric relaxation under various pressures was obtained by measuring the relaxation frequency at various temperatures. Series of measurement shows that pressure and the amount of MH have little effects on relaxation frequency and its activation energy. Meanwhile, the permittivities of MH at DC field and high frequency depend on the amount of MH, but not on pressure.