Relay-race interaction in microwave devices

Abstract

Relay-race interaction is a collective interaction of the extended pre-modulated electron bunches under the condition of coherent (synchronous) addition of the radiations arising in the regions of short-term interaction between partial electron beams and the field of a fast space harmonic. Work-predecessors in which the principle of relay-race transformation to high-frequency energy in microwave devices was used are Bolotovsky's works [1, 2] and the work [3]. In [1, 2] the radiation of virtual sources moving at an arbitrary velocity (including superluminal one) was considered. In [3] the coherent deceleration radiation of extended electron bunches was analyzed. By analogy with superluminal radiation sources in the microwave vacuum devices the term "electron hare" was used ([4-6]).The "electron hare" is the virtual oscillator concentrated in a short interval of the space-time range. It is capable of moving at an arbitrary velocity, including the superluminal one, in a certain direction.Realization of the "radio hare" in vacuum microwave devices provides an opportunity of interaction between the moving electrons and the fast space harmonics of the microwave field. Later in [7-10] the term "relay-race interaction" which reveals an idea of using the "electron hare", was used. The simplified scheme of the real vacuum microwave device with relay-race interaction between the modulated sheet electron beam and a vertical field component of the space harmonic of the periodic structure located in the open resonator, at an oblique incidence of electron bunches (at an angle  to the periodic structure) is depicted in Fig. 1. It shows that implementing the relay-race interaction principle in this particular scheme assumes the conditions of both velocities to be equal: the velocity of the intersection point of the electron bunch front and the periodic structure (the "electron hare") and the phase velocity of the space harmonic (not necessarily decelerated). The oscillator design with relay-race interaction shown in Fig. 1, was patented [11]. Possibilities of using of relay-race interaction of electron beams for the development of millimeter and submillimeter wave sources are analyzed in [9,10]. The theoretical studies of the relay-race interaction oscillator are described in [12][13][14].