Microwave Generation by FEL
Generation of Microwave Radiation by FEL with Sheet Electron Beam and Two-dimensional Distributed Feedback.
Tech Area / Field
- INS-DET/Detection Devices/Instrumentation
8 Project completed
Senior Project Manager
Urezchenko V M
Budker Institute of Nuclear Physics, Russia, Novosibirsk reg., Akademgorodok
- VNIITF, Russia, Chelyabinsk reg., Snezhinsk\nRussian Academy of Sciences / Institute of Applied Physics, Russia, N. Novgorod reg., N. Novgorod
- JAERI / Tokai Research Establishment, Japan, Tokai Mura
Project summaryThe objective of this project is to construct a tunable 4mm microwave generator producing several hundreds megawatt power of coherent radiation at a few microsecond pulse duration. To solve this problem we have chosen the way of using the scheme of Free Electron Laser (FEL) that is driven by sheet relativistic electron beam at some kAs current. This generator should be called more exactly Free Electron Maser (FEM). For obtaining of the coherent radiation this generator should be operated with two-dimensional distributed positive feedback. Already now, at the sheet electron beam experiments on the U 2 accelerator in the FEL with one-dimensional distributed feedback we have obtained more than 100J energy content in the microsecond pulse of the microwave radiation. Development of these experiments allows to achieve the objective of the project.
In principle the chosen way will allow us in the future to achieve 1-10GW power level for millimeter and submillimeter radiation at ten microsecond pulse duration. Taking into account the energy recuperation of the used electron beam and possibility of the repetitive operation of such microwave generator, this generator can be used for various scientific investigations and practical applications. Among them there are the cleaning of the top layers of the Earth atmosphere and restoration of its ozone layer, the transporting of the energy between installations in the cosmic space, the obtaining of plasma with the fusion parameters in magnetic confinement fusion reactor and the sintering of micrograin ceramics. Construction of the powerful microwave generators and their using for solving such global problems are the real field for employment of the Russian weapon scientists.
The selected approach to solve the problem of the obtaining high power radiation, allows one to create the microwave generator differing from the others by the following positive qualities.
1. Millimeter and submillimeter ranges of wavelengths are guaranteed by the relativistic velocities of the beam electrons as well as by small spatial period of a plane magnetic undulator according to a small thickness of the sheet beam.
2. Operation of the generator with the electron beam current of a few tens of kAs can be realized due to opportunity of the stable propagation of the sheet beam in the plane undulating magnetic field even if the beam width in orders of magnitude exceeds the beam thickness.
3. Good efficiency of the energy transfer from the beam electrons to the microwave radiation is provided by the existing of opportunity to achieve a small angular pergence of the beam electrons at a high density of the beam current.
4. Good spatial coherence of the radiation produced by the generator, is expected by using a new approach in the creation of the transverse flows of the radiation inside the resonator that realizes 2-dimensional distributed feedback.
5. Sufficiently high efficiency for the PEL predicted by the theory is added by the opportunity of beam energy recuperation and by high efficiency of the energy transfer from an accelerator capacitor storage to the electron beam. It should provide the total efficiency from feeding circuit to the emitted radiation on the level about 60%.
In the fundamental physical sense our investigations on FELs with the sheet beams give possibility to study some problems of the modern physics. The first one is an equilibrium and stability of the high current beam with strongly elongated cross section. The second one is the using of 2-D distributed positive feedback for a single mode generation of the electromagnetic waves at very large transverse size of their flow. From another hand for practice, realizing of this project will give a base for solving global problems on energetics and ecology of the Earth. Participation of the weapon scientists in the doing of this project allows them to go step by step from military studies to the solving these civilian problems. In case of the positive result of the investigations it can be expected a large profit for the institutions taking part in this project because the power microwave generators will be needed for the industry all over the World.
The work on the project may provide on a base of mutual cooperation with foreign scientists studying similar problems. Projects of the microwave generators operated as a Free Electron Laser with a high current electron beam, are under development in University of Maryland and Mission Research Corporation (United States of America), in Rijnhuizen (Europe) and in Naka (Japan).
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