This paper is to present a concept of a modular and scalable High Temperature Boost ( HTB ) Power Processing Unit ( PPU ) capable of operating at temperatures beyond the standard military temperature range . The various extreme environments technologies are also described as the fundamental technology path to this concept . The proposed HTB PPU is intended for power processing in the area of space solar electric propulsion , where reduction of in - space mass and volume are desired , and sometimes even critical , to achieve the goals of future space flight missions . The concept of the HTB PPU can also be applied to other extreme environment applications , such as geothermal and petroleum deep - well drilling , where higher temperature operation is required .