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The development of periodic structures for use as oscillators and amplifiers in the millimetre and sub-millimetre region has been an important topic in science in recent years [1–4]. The 2D periodic structure used in this instance to form the interaction region has a potential for application in sources of high power microwave and THz radiation [5]. Such a structure can be observed using a hollow,...
We present the results of study of a Cherenkov maser based on a 2D periodic lattice used to achieve the desired level of output power while still maintaining the coherence of the output radiation. In this case the large interaction region formed by the periodic lattice allows a moderate power density inside the beam-wave interaction space whilst simultaneously avoiding the formation of electron beam...
A novel interaction cavity has been designed for a gyro-oscillator, allowing co-harmonic generation at the 2nd and 4th harmonic resonances of the cyclotron frequency. The output aperture of the cavity has been designed to trap the lower harmonic, whilst allowing output of the upper harmonic. Results from recent numerical simulations, performed using MAGIC 3-D, are presented. The intended co-harmonic...
Two-dimensional distributed feedback is an effective method of producing ultrahigh-power spatially coherent radiation from an active medium, that is spatially extended along two coordinates, including relativistic electron beams with sheet and annular geometry. This paper describes the progress in the investigations of planar and coaxial free-electron masers (FEMs) based on a novel feedback mechanism...
Periodic structures are studied in many branches of physics including photonics, optics, electronics and physics of condensed matter, resulting in the appearance of photonic band gap materials, lasers, passive and active devices based on such lattices. Here the concept and the results of studies of a Cherenkov maser based on a surface two-dimensional periodic lattice are presented. The basic model...
High power millimeter and sub-millimeter wave sources operating in the high GHz - THz (35 GHz-1 THz) frequency range are important for a number of applications. This work will focus on the overview of recent theoretical and experimental research conducted at the University of Strathclyde to design, build and study masers operating at 37.3 GHz, 91.2 GHz and 0.74 THz. The results obtained will be presented...
Summary form only given as follows. For an active media, that is spatially extended along two coordinates, including relativistic electron beams with sheet and annular geometry, as well laser media, the use of two-dimensional (2D) distributed feedback is beneficial for providing spatial coherence of the radiation and, thus, can be used to increase the total radiation power. Such 2D feedback can be...
This paper presents an overview of a coaxial free-electron maser (FEM) based on 2D and 1D distributed feedback, driven by a large diameter (70 mm) annular electron beam. Most recent experimental results and numerical simulations are presented and discussed. Particle in cell (PiC) code MAGIC is used to demonstrate the possibility to control the operating mode and frequency of the output radiation....
This article presents the design and numerical study of a high-power maser based on a 2D periodic structure and operating in the W-band (75-110 GHz) frequency range. The maser is capable of generating spatially and temporally coherent radiation wherein a 2D periodic structure is used to provide the distributed feedback and synchronize the radiation. The periodic lattice also acts as a slow wave structure...
High power millimetre-wave sources operating in the W-band (75 GHz-110 GHz) frequency range are important for a number of applications. This work will focus on the design and construction of a high power maser operating in the W-band frequency range, which can be capable of generating spatially and temporally coherent radiation at a power of at least 10 MW.
Summary form only given. The latest results from our 450 kV, 70 kA, 240 ns pulsed power supply are presented. This power supply has been used to produce a 2 kA electron beam to drive a Free Electron Maser and produce high power (60 MW) coherent microwave radiation from a highly oversized cavity. Future developments require a reduction in power supply size and weight, increased repitition rate operation...
Summary form only given. Intensive studies of operation of a coaxial high-power Free-Electron Maser (FEM) based on a two-dimensional distributed feedback are currently taking place at the University of Strathclyde. It has been demonstrated that highest output power and efficiency was achieved if the FEM two-mirror cavity was formed by a 2D Bragg (input mirror) and 1D Bragg structure (output mirror)...
Summary form only given. High power millimetre-wave sources which produce coherent radiation (masers) are very important for a number of applications in science and engineering. To observe coherent radiation, the interaction between electrons rotating in a static magnetic field and an electromagnetic wave must take place inside the gyrotron's cavity. The gyrotron is one of the best known broadly applied...
The results of experimental studies of a coaxial free-electron masers (FEM) based on two-dimensional distributed feedback are presented. In the first set of experiments the FEM's interaction region was formed by a two-mirror cavity with 2D Bragg structures as input and output mirrors. In the second set of experiments a cavity with 2D and 1D mirrors was used. In both cases the input mirror provided...
The analysis of electrodynamic properties of two-dimensional (2D) Bragg resonators of planar and coaxial geometry realizing 2D distributed feedback was carried out in the frame of the coupled-mode approach and in 3D simulations taken into account. High selectivity of above structures is demonstrated for large Fresnel parameters. Formation of the high-Q eigenmodes in the vicinity of the Bragg resonance...
The study of a co-axial free-electron maser (FEM) based on 2D and ID distributed feedback and driven by a large diameter (70 mm), annular electron beam is presented. It has been demonstrated that 2D distributed feedback in the input mirror allowed 8 mm radiation emitted from different parts of the oversized electron beam to be synchronized. The FEM operating in the (35.9 GHz to 38.9 GHz.) frequency...
The use of two-dimensional (2D) distributed feedback has been considered as a method of providing spatially coherent radiation from an oversized annular electron beam used to drive a FEM based on a coaxial two-mirror cavity. The operation of the FEM when the interaction space is formed by a 2D Bragg input and a 1D Bragg output mirror separated by a regular section of the coaxial waveguide has been...
High power millimetre-wave sources operating in W-band (75 GHz-110 GHz) frequency range which are capable of generating coherent radiation at high power up to a few 10s of MWs are important for a number of applications. In order to achieve coherent radiation at high power, the use of an oversized electron beam is required. The use of a 2D periodic lattice was suggested to obtain 2D distributed feedback...
We report the results of studies of operation of the coaxial FEM based on two-dimensional distributed feedback. The cavity formed with the novel Bragg structures has been used. The FEM output radiation is studied and output power is measured
Summary form only given. First experimental study of operation of a co-axial free-electron maser (FEM) based on a two-mirror cavity formed by a 2D Bragg input and 1D Bragg output reflector is presented. The input mirror provides two-dimensional (2D) distributed feedback and ensures mode selection over the wave azimuthal index. The use of a 1D Bragg structure as an output mirror reduces the cavity...
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