研究目的
Investigating the transition and propagation mechanism of the ionizing wavefront in laser-absorption waves using optical emission spectroscopy and high-speed shadowgraphy.
研究成果
The FIW–LSDW transition is detectable from the shadowgraph and CJ-detonation theory related to shadowgraphy conducted with a high-speed camera. The plasma behind the FIW wavefront was found to have an electron temperature of 0.7 eV and an electron number density of 2.5 × 1023 m?3. For LSDW, the electron temperature was about 1 eV behind the wavefront, and the electron density was about 2.7 × 1023 m?3. At the threshold of FIW and LSDW, the electron temperature and density were, respectively, 0.3–1.0 eV and 2.2 × 1023 m?3.
研究不足
The McWhirter criterion reveals that the existence of LTE in plasma behind LSDW, or even FIW, was not clearly satisfied in the experimental condition. Consequently, the electron temperature near the front of LSDW was uncertainty estimated by the Boltzmann plot and the Saha equilibrium technique.
1：Experimental Design and Method Selection:
High-speed visualization and optical emission spectroscopy were used to investigate the transition of the laser-absorption wave in argon gaseous form. A 5 J CO2 pulse laser, an Echelle spectrometer, and an intensi?ed CCD camera were used for the quantitative investigation of the plasma temperature and density.
2：Sample Selection and Data Sources:
Argon gaseous form was used as the atmospheric gas to conduct the chemical reaction simply and to sustain the long period of FIW.
3：List of Experimental Equipment and Materials:
A transversely excited atmospheric CO2 pulse laser (5 J/pulse, TEA-101; GSI Group Inc.), an Echelle spectrometer (f/7, 195 mm focal length, Mechelle 5000; Andor Technology), an ICCD camera (1024 × 1024 pixel resolution, 5 ns minimum exposure time, iStar DH334T-18F-E3; Andor Technology), a xenon pencil style spectral calibration lamp (6033; Newport Corp.), and a standard of the spectral irradiance tungsten lamp (OL245 M; Optronic Laboratories, Inc.).
4：Experimental Procedures and Operational Workflow:
The spectrometer gates and laser operations were controlled using a pulsed-delay generator (DG535; Stanford Research Systems Inc.), which first receives a trigger signal from the lasers. After adding a delay, it triggers the camera and the shutter controller. The ICCD gate time was 100 ns.
5：Data Analysis Methods:
The electron temperature and spectral broadening were used to calculate the electron density considering the in?uence of electrons of the Stark effect.
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