A method for converting hydrocarbon materials into a product includes receiving a hydrocarbon feedstock in a first reaction chamber, receiving a process gas in the first reaction chamber, and forming a first set of discharge conditions in the presence of energy from a microwave generator, in the first reaction chamber, to convert the hydrocarbon feedstock into an intermediate product for delivery to a second reaction chamber. The method also includes delivering the intermediate product to the second reaction chamber, forming a second set of discharge conditions, and converting the intermediate product into a final product in the second reaction chamber.