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Author(s):
J. Miyazawa, H. Yamada and M. Matsuoka
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Title:
Gas Flow Velocity of the Direct Gas Puff
Date of publication:
Aug. 2003
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Key words:
gas flow velocity, direct gas puff, sound velocity, supersonic, LHD, experiment
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Abstract:
Gas flow velocity of a piezo-valve used in the Large Helical Device has been measured in a test chamber of 3.6 m long. Various gasses of hydrogen, helium, methane, neon, nitrogen and argon are used in the experiment. In the direct gas puff configuration, where the gas flow directly reaches the target, the Mach number increases with the mass of the gas molecule and/or the primary pressure of the piezo-valve. The maximum Mach number of over 1.5 is obtained with the methane. In the normal gas puff configuration, where the injected gas suffers from reflection and/or absorption by materials, the gas flow velocity remains at sound velocity, even with the methane.
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