Abstract: This invention provides an efficient counter flow heat exchanger of various rectangular, cylindrical or spiral shapes, having two flow channels or more and four inlet/outlet or more. Wherein flow channels have a plurality of passageways created by interposing a roll formed metallic between metallic rectangular sheets to form the flow channel or chamber. Rectangular and roll formed sheets sealingly joined by linking means, preferably but not necessarily by continuous linear spot welding or argon welding process.

Abstract: This invention provides an efficient counter flow heat exchanger of various rectangular, cylindrical or spiral shapes, having two flow channels or more and four inlet/outlet or more. Wherein flow channels have a plurality of passageways created by interposing a roll formed metallic between metallic rectangular sheets to form the flow channel or chamber. Rectangular and roll formed sheets sealingly joined by linking means, preferably but not necessarily by continuous linear spot welding or argon welding process.

Abstract: A radioactive isotope electrostatic generator may include emitter electrodes and collector electrodes. The emitters and collectors may be made of low atomic weight material, and may be formed as a mesh. A radioactive isotope may be homogenously distributed on the emitter electrodes.