The augmentation of a ballistic process, based on the well known solid propellant burning by an electrothermal (ET) energy source, is the subject of an experimental and theoretical investigation to obtain improved launching techniques. The plasma jet formation method, the internal ballistics modeling approach and the experimental test bed are described. Experimental results are disclosed showing the enhanced burning rate of a solid propellant ignited and augmented by the injection of plasma jets. We also present preliminary experimental evidence of improved performance of the new proposed method over that of conventional ballistics using solid propellant alone.
An overview of the equations of state (EOS) with a short summary of shock wave experiments with laser induced impact flyer, relevant to EOS study, is presented. The "old-new" ellipsometry is suggested and described for the EOS research. The detection of phase transitions of the first kind (solid-solid) as well as phase transition of the second kind (Curie point as an example) is demonstrated. Furthermore, the temperature measurements are not possible without the knowledge of the emissivity, a parameter that can be measured by using ellipsometry techniques.
A solid-propellant electrothermal-chemical (SPETC) 40-mm gun has been designed, constructed, and tested in the indoor firing facilities of the Soreq Propulsion Division Laboratory. An external injector device converts the electric energy stored in the capacitors of the pulse forming network (PFN) into a high-temperature plasma jet that penetrates the gun cartridge and boosts the whole ballistic process. However, unlike large-caliber SPETC systems, in which electric energy is limited to ignition purposes, the 40-mm SPETC gun is a genuine hybrid gun with almost equal electric and chemical contributions. There is experimental evidence that this unique feature induces a very peculiar initial propellant temperature compensation mechanism. It seems that when a significant part of the propelling energy comes from the plasma, i.e., electric energy is not only predominant at the ignition stage of the firing but also later on, then the temperature sensitivity of the propellant tends to vanish. A simple theoretical model supports the experimental findings. The large amount of electric energy is also responsible for a recorded ballistic improvement of 15% in the projectile muzzle kinetic energy. Calibrated simulations show that an optimal tailoring of the power pulse shape and suitable propellant grain geometry should further increase by 10% the muzzle kinetic energy. These modifications are in progress and results should be soon available.
A fiber-optic confocal sensor for noncontact ballistic measurements is described. Determination of motion at velocities of 1.7 km/s with an uncertainty as small as ±0.3% is demonstrated for both a projectile and a free-surface target. The fibers detect the passage of the object at their conjugate image points created by low F/# optics. This results in an output signal comprising a train of sharp pulses each precisely identifying when the ballistic object traverses an image point. Since the ballistic object does not contact the sensor at the time of imaging, the measurements do not perturb the motion, enabling multi-fragment measurement, as well as repetitive measurements of the same object point.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.