ETC research at Soreq NRC, Israel
An overview of the electro-thermal-chemical launcher (ETC) research program at the Propulsion Physics Laboratory, Soreq NRC, Israel is presented. The main avenue explored is a detailed study of solid propellant ETC (SPETC) performance and optimization. A better knowledge of the physical phenomena taking place inside the device and in parallel efforts to tackle the engineering aspects of specific weapon systems based on the SPETC concept. Theoretical and experimental tools have been developed. Permanent efforts towards developing optimal and efficient components for such systems are invested. A second avenue is the design and the construction of a small caliber ETC demonstrator, as an answer for present military demands for urban combat conditions. All system options are dealt with including a novel inductive pulse power supply.
A proof of the need for consistent treatment in modelling of capillary ablative discharges
In the framework of a one-dimensional model for plasma flow in ablative capillary discharges, we use a consistent method for obtaining the appropriate boundary conditions, and a new method for describing the radiative energy flux from the plasma to the wall. Good agreement is reached between the calculated and the measured values for the temporal behaviour of the plasma's main parameters. The agreement is particularly satisfying for the plasma conductance (resistance), the voltage across the capillary, the total input energy, the maximum input power and the plasma pressure. This gives us confidence that the model also predicts correct values for the remaining plasma parameters that are difficult to measure accurately, such as the plasma density, the temperature and the velocity (inside the capillary as well as at its exit). The knowledge of these parameters is crucial in order to use the ablative capillary as an efficient plasma source for different applications.
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.