Future　radar　and　military　communication　systems　need　powerful　signal　generators　with　much　higher　frequencies.　In　this　paper,　the　preliminary　studies　of　a　high　power　terahertz　wave　generator　are　presented.　A　novel　2.5D　fully　electromagnetic　particle-in-cell　simulation　tool,　UNIPIC,　is　introduced,　and　with　this　code　we　investigated　the　＂hot＂　characteristics　of　a　prototype　0.14　THz　wave　generator　in　superradiant　regime.　The　influences　of　some　operating　parameters　on　the　device　performance　are　also　studied,　and　a　set　of　optimal　values　are　finally　obtained　according　to　the　requirement　of　maximal　output　peak　power.