Abstract: An improved collimator for a plasma arc torch consists of an annular holder member and an insert member. The insert member includes a tubular stem portion ending in an integrally formed, radially extending face plate. When the stem portion is fitted into the central bore of the holder member with a predetermined clearance fit therebetween, a cooling water passage is created. The improved collimator is characterized by the absence of any welds between the holder member and the insert member that would be exposed to conductive gases given off during use of the plasma arc torch and a lesser resistance to cooling water flow than prior art collimator designs.

Abstract: A regenerative heat exchanger system includes a heat accumulator provided in an insulating vessel for accumulating heat energy, the heat accumulator having a first end and a second end opposing to the first end and being capable of permitting gas to flow through a body between the first and second ends, a heating device for heating the heat accumulator in such a manner that the heat accumulator is formed with a plurality of temperature-different regions, a medium gas-supplying device for flowing medium gas through the plurality of temperature-different regions independently from one another.