| 摘要 |
PROBLEM TO BE SOLVED: To provide a detonation velocity measuring instrument free from the possibility of damaging a sheath pipe and a coil, capable of enhancing an output voltage of a detection signal, and capable of enhancing a detection sensitivity (S/N ratio). SOLUTION: In this detonation velocity measuring instrument, a detonation velocity is measured by measuring a time interval when a detonation wave propagated in the sheath pipe passes two fixed points A, B. The measuring instrument is provided with the detection coil 21 located in two fixed point portions to surround the sheath pipe 11, a permanent magnet unit 40 for generating a magnetic field inside the detection coil, and a transient phenomenon recorder 30 for recording a transient phenomenon of the detection coil as to a time axis. The permanent magnet unit 40 comprises a plurality of compound permanent magnets 42 having an N-pole and an S-pole with a space along an axial direction of the detection coil, and the respective compound permanent magnets are positioned symmetrically with respect to an axis of the detection coil 21. COPYRIGHT: (C)2005,JPO&NCIPI
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