Description: The purpose of this project is to demonstrate the feasibility of a new class of electronic devices called solid state vacuum devices (SSVD^TMs), a highly enabling technology for extreme high temperature radiation hard electronics. SSVD^TMs merge solid state semiconductor technology, including process fabrication techniques, with vacuum electronics, and, in this case, specifically thermionic vacuum electronics. SSVD^TMs have already been demonstrated for highly demanding high frequency applications. Thermionic SSVD^TMs, in which vacuum transport is by thermionically emitted electrons, are especially promising due to their intrinsic internal high temperature operation and radiation hardness. SSVD^TMs are extremely well suited for extreme environments that, for example, exist on or near Venus. InnoSys proposed and successfully demonstrated in Phase I of this SBIR project SSVD^TM triodes/field effect transistors and the associated assembly and sealing to meet the requirements needed for extreme high temperature electronics. In particular, SSVD^TM electronics were successfully experimentally demonstrated fully operational at 500C. In addition, radiation insensitive SSVD^TM electronics were also successfully experimentally demonstrated during Phase I of this SBIR project. Small scale extreme temperature, radiation insensitive SSVD^TM integrated circuits (ICs) will be developed during Phase II of this SBIR project. Currently no other existing electronics can address this extreme environment.