High current short pulse generator for pulse magneto-oscillation (PMO) research

Pulse magneto-oscillation (PMO) is one of the new techniques, developed for solidification structure refinement of metals and alloys, as it is was found in experimental results from the last decade. When electromagnetic pulses are applied to a molten metal during its solidification, the Lorentz forces causes to pressure waves, which change the microstructure from columnar dendrites to globular grains. PMO has a great potential in precise controlling of the solidification microstructure. The current work presents the development and the construction of a high current short pulse generator, which was required for the PMO research. The sample configuration consists of the non conductive crucible with a molten metal, which is placed coaxially inside a solenoid coil. The pulse generator is able to introduce short pulses with current amplitude of kA order into the coil. The proposed generator is based on resonance LCL circuit structure using a high current SCR switch. The fundamental idea of the power system is to convert a low-power, long-time input into a high-power, short-time output. Using resonant LC topologies, the durable resonant capacitor charging process established firstly, drawing low current from the net. Afterward, high frequency, high amplitude capacitor discharging process provides the necessary current to the work coil. The calculations and simulations of the system parameters and operation are described and the results of the experimental system behavior are shown. The theoretical considerations and the test results were found to be closely resembled.