For the purpose of fusion research (W7X, ASDEX-U), the HUN-REN has developed a new insulation method for high voltage transformers. This method deviates from the traditional use of resin casting or oil-based insulation, by using rotary friction welding (FSW) to join the new transformer’s architecture components within a mechanically robust assembly with optimal insulation. This technology enables the production of transformers that are not only lighter and more compact but also offer enhanced performance characteristics such as superior insulation capabilities and increased efficiency. Transformers have been successfully produced and tested with power ratings up to 10kVA and insulation capabilities of up to 120kV and are now suitable for a wide range of applications such as ion sources for accelerators and applications involving the insulation of heating and high-voltage components