Vacuum gauge available from high vacuum to beyond atmospheric pressure based on leakage of surface acoustic wave propagating on ball to surrounding gases.

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The pressure dependence of the leaky attenuation was measured using ultra-long propagation of naturally collimated surface acoustic wave (SAW) in a ball SAW device and the realization of the vacuum gauge available from beyond atmospheric pressure was attempted. The ball SAW device with an interditgital transducer of Al film, useful for suppressing the scattering, succeeded in measuring the waveform after propagating 1 m by S/N of 20 at 100 kPa in N2. Moreover, precise measurement of the attenuation was succeeded by fitting an amplitude decay curve to an exponential function. The leaky attenuation is measured by subtracting extraneous attenuation independent of the pressure. As a result, it was observed that the pressure dependence was linear in the pressure range from 300 kPa down to 0.03 kPa. From these results, the foundation of the pressure gauge available beyond atmospheric pressure was established based on the measurement of the leaky attenuation by the ball SAW device.