D6: Computer modeling and design of electronic and optical devices Development of Smith-Purcell FEL using vacuum microelectronics technology Yuri A. Romantsov Radio Astronomy Institute of Ukrainian Acad. of Sc. Kharkov,Ukraine ( Phone: (7-0572) 44-87-18, Fax: ( 7-0572) 47-65-06 ) Introduction Vacuum microelectronics ( VM ) technology comes from silicon industry has been shown now great promise for novel microwave electronic devices [ 1 ]. One possibility is that new types of millimeter wave Smith-Purcell free electron lasers may be developed with the applying of low voltage matrix field- emission electron sources. In the present paper, the new amplifiers and oscillators of millimeter and submillimeter wave bands named as orofemitrons [2] are introduced. Theory and design The main elements of orofemitrons construction are an open resonator with the distributed interaction and special electron gun with the field-emission emitters whose current is modulated by the microwave signal. It seems to us the perspectiveness of the orofemitrons is stipulated by the use in one design of the most effective in millimeter & submillimeter wave bands orotron electrodynamic system and the phenomena of microwave modulation of fieldemission .This technique of electron current bunching showed its effectiveness in femitrons -amplifiers and multipliers of X-band . For example, a schematic diagram of the orofemitron-amplifier is shown in Fig. The input signal power Pinp increase due to the sharp slope of FowlerNordheim current-voltage characteristics of electron emitter and the effective distributed interaction of electron beam with the open resonator field , as well as due to the shaped electron bunches power increase under additional acceleration by voltage Ua between emitter surface and output resonator. The orofemitrons theory depend on the original mathematical model of microwave bunching of field emission current and on well-known methods[3] of joint solution of Maxwell's equations & equations of motion for resonance systems with distributed interaction. Conclusion The latest achievements in the VM technology and miniature open resonators design used for development of orofemitrons allow to create compact high stability oscillators & amplifiers with output power Pout 1100 W and efficiency 1050% in the middle range of MM waves References [1]Vacuum Microelectron. Dev.,IEEE Tr. Electron. Devices. ,36,11,1989,part 2 [2]Yu. A. Romantsov,Proc. of Int. Conf. on MM wave & F.-In.Tech.,Beijing,August,1992. [3]D.Vavriv & O.Tretyakov,Theory of the Resonant Amplifiers with distributed interaction,"Nauk. Dumka",1989