| Paper | Title | Page |
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| MOPPH020 | FEL with Orotron Type Feedback | 61 |
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| In microwave electronics orotron is widely used as a source of RF radiation in millimeter and submillimeter wavebands. In this device an electron beam is coupled to a mode of quasi-optical resonator by means of the periodical grating one of the resonator mirror. In our paper we discuss a relativistic modification of such a device. A novel FEL scheme is suggested in which the slow wave structure of orotron is replaced by shallow Bragg corrugation which provides the coupling of the transverse (with respect to direction of beam propagation) mode of a two-mirror cavity with longitudinally propagating wave. The latter can be excited by the electron beam wiggling in undulator field. Described scheme allows to combine selective properties of an orotron with relativistic frequency conversion of a free electron laser. The transverse mode provides the feedback in the system thus leading to self-excitation, while the propagating wave is responsible for energy extraction in the steady-state regime of operation. The discussed system was investigated both analytically and numerically using direct codes and averaged equations approach. | ||
| MOPPH063 | Potentialities of ELMI Device for Submillimeter Generation by Stimulated Intercavity Scattering in Planar FEM | 156 |
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Paper describes main features of a project on two-stage generation of submillimeter radiation at the ELMI device. This novel variant of a two-stage scheme based on stimulated intercavity scattering was proposed earlier in the paper*. In accordance with the scheme, at the first stage a sheet electron beam drives a 2D Bragg free electron maser (FEM) of planar geometry to generate 4-mm pump wave. At the second stage this wave undergoes stimulated scattering at the supplementary electron beam to produce submillimeter radiation. A key feature of a proposed scheme is to use two sheet beams with a few kiloampers currents that transported in parallel channels, which are connected by a special waveguide* for synchronization of beam radiation in different channels**. Production of two sheet beams by one accelerator diode with two cathodes is also similar to the process of operation of the multibeam diode described in Ref.**. Two-stage scheme allows us to use high power 4-mm radiation produced in the first channel by the sheet beam moving in an undulator quasi-static magnetic field, as an EM-undulator for the secondary stage FEL operating in Terahertz wave range. In the paper we describe results of theoretical and experimental investigations of various aspects of the two-stage scheme and some testing experiments on units for realization of this scheme at the ELMI device.
* A. V.Arzhannikov et al. Proc. Int. Workshop, N. Novgorod, Vol.1,p.228-232,2006.** A. V.Arzhannikov et al. Digest Tech. Papers, PPPS-2001, Las Vegas, Nevada, Vol.1, p.561-564,2001. |