Experimental ablation processes study on an electrothermal launcher
An experimental parametric study has been performed to analyse the influence of time on the ablation processes in the capillary of an electrothermal launcher. A 600 kJ, 16 cells pulse forming network (PFN) was used. The time discharge was varied from 350 /spl mu/s to 100 /spl mu/s by changing the cell number (from 16 to 4) and then the capacitance (from 1760 /spl mu/F to 440 /spl mu/F). The parametric study has been performed at a constant voltage level (13 kV). The ablated masses have been measured for different time discharge and the results have been compared with a 0-D code.
Investigation of the performance of an electrothermal plasma source with extended pulse length
Electrothermal (ET) plasma sources operating in the ablation-controlled arc regime uses discharge currents with pulse lengths between 100µs to 1ms. Faster or longer or extended flat-top pulses can also be generated to satisfy various applications of ET sources. It was reported that shorter pulse length of about 300ms is more powerful but provided shorter time duration for the interaction of the plasma flow with a solid target, and that the pulse is a key parameter for effective ignition of plasma propellant interactions1.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.