Laser-supported detonation (LSD) is a type of supersonic flow, which is considered as a very important phenomenon in laser propulsion systems because it can generate high pressure and temperature. On the other hand, LSD transforms to LSC (Laser-supported combustion wave) when the irradiative laser power becomes weaker. In this study, the LSD-to-LSC-transitions in periodically variable laser irradiations for both argon and hydrogen gases are investigated by computational fluid dynamics (CFD) analyses, using a thermochemical nonequilibrium model. In considering both of LSD-to-LSC transition and LSC-to-LSD restoration, hydrogen gas is easier to remain the transformations by a shorter periodic irradiation.

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A non-segmented constricted arcjet is widely used as a compact high enthalpy wind tunnel and electric propulsion device. When argon is used as the operating gas, it operates in the low voltage mode, which is known to be unstable. The upstream subsonic flow conditions and the electrode configuration can influence its discharge instability and characteristics, but there is little research investigating them. The present study investigated these influences using computational fluid dynamics. The upstream rectification effect was found to be insignificant for the discharge characteristics. In contrast, the electrode configuration was shown to have a strong influence on the discharge mode: as the anode start position—the boundary between anode and insulator—moves downstream, the arc attachment point moves with it. This suggests that by adjusting the anode start position it is possible to shift the discharge voltage mode from low (5 V) to high (24 V).

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The effect of pulsed electric fields (PEF) on the endogenous enzyme of scallops to prevent degradation of ATP-related compounds was investigated. A crude enzyme solution was prepared by dissolving powder of scallop adductor muscle into 0.5 M NaCl solution. The solution was centrifuged at 4000 rpm for 5 min at 4 °C and the resulting supernatant and precipitate were subjected to PEF treatment. After PEF treatment, ATP (final concentration of 1.9 mM) was added as substrate. After reaction time of 0 ~ 24 hours, the enzyme reaction was quenched by adding perchloric acid solutions. ATP-related compounds were determined using liquid chromatography. In the case of the supernatant, the rate of ATP degradation increased with increasing salt concentration and no inactivation of ATP-degrading enzymes was observed by PEF treatment. In the case of precipitates, the ATP degradation rate degradation rate constant was -5.5×10-5 s-1 for the control and -1.2×10-5 s-1 for the PEF sample at 500 mM, indicating a 4.6-fold decrease in reaction rate. This result indicates that the ATP-degrading enzyme was inactivated by PEF treatment.

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