Overview of ETC research in Korea

In late 2000, an experimental 30-mm electrothermal-chemical (ETC) gun, a data acquisition system, and a 2.4-MJ pulse-forming network (PFN) consisting of eight 300-kJ modules were constructed, and serious research projects were started. During the past years, basic studies on the effect of the electric pulse in the process of ignition and propulsion of the gun have been done. Two types of ammunition, an exploding wire cartridge and a capillary plasma injector cartridge, were used in the experiments. The load resistance should be estimated well in order to deliver electric energies into the combustion chamber as a desired form in time. For that purpose, there has been an effort to model the load resistance of the ETC gun, which shows the dependence on the pressure of the combustion chamber. A study on a capillary plasma itself is also an important topic and is now in the beginning stage of research using spectroscopic diagnostics. The capillary plasma discharged in the open air provides useful information through the comparison with that discharged in the ETC gun. In the development and operation of the PFN, some problematic characteristics such as a high-voltage surge leading to a destruction of crowbar diodes occurred. A countermeasure was presented to solve the problem. High-current switches are also being studied. Vacuum rotary arc gap switch, pseudospark switch, triggered vacuum switch, and inverse-pinch switch are being studied for better and reliable operations. The ETC program in Korea is currently concentrating on the detailed investigation on the interaction of a plasma with propellants.