Yosuke KUROSAKA, Kohei SHIMAMURA
DOI Number: N/A
Conference number: HiSST-2024-260
In this study, a 28 GHz millimeter-wave interferometer was constructed to measure precursor electron number density. Measurements were made using a 9 m long free-piston driven expansion tube. Air was used as the test gas. The electron number density corresponding to the precursor in front of the strong shock wave was generated behind the shock wave at about 3 km/s. Measurements were made in two directions, one orthogonal to the expansion tube and the other in the direction of the shock wave. The receiving antenna was a coaxial waveguide transducer mounted on the side of the low-pressure tube. The transmitting antenna was a coaxial waveguide transducer mounted opposite the receiving antenna for the orthogonal measurement. A horn antenna mounted in the test section was used for distribution measurement. The result of the orthogonal measurement was obtained an electron number density of 3.13 × 1016 m−3 at the shock velocity of 3.22 km/s. This result is 0.465 times larger than the NASA CEA calculation. The line-density in the distribution measurement was obtained as 2.0 × 1016~3.0 × 1016 m−2 at the shock velocity of 2.85km/s. However, it is necessary to verify this result by another measurement method.
