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Microwave Generator

#B-290


Generation of Electromagnetic Radiation by High-Current Relativistic Electron Beam in Acoustic Undulator

Tech Area / Field

  • INS-OTH/Other/Instrumentation

Status
3 Approved without Funding

Registration date
06.09.1998

Leading Institute
National Academy of Sciences of the Republic of Belarus / Institute of Radiation Physics and Chemistry Problems, Belarus, Minsk, Sosny

Supporting institutes

  • Belarussian State University / Scientific Research Institute of Nuclear Problems, Belarus, Minsk

Project summary

Purpose of the project is the development of new variant of the generator of a microwave range - acoustic undulator - device, in which a relativistic high-current electron beam (RHCEB) becomes a source of the directional electromagnetic radiation as a result of interaction with intensive acoustic (or weak shock) wave excited in neutral gas of a drift tube. The realization of this purpose supposes to carry out all-round both theoretical investigations and experimental works. A finite product of the project will be a demonstrable sample of the device.

The project realization would mean extension in Belarus of researches on a scientific direction, actively developing in the world, - relativistic high-frequency electronics, which has reached impressive successes in the field of application of electron beams of high energy for generation of powerful electromagnetic radiation. Result of this development was creation of a numerous super-high-frequency (SHF) devices of decimeter and centimeter ranges.

The advance in region of smaller lengths of waves and obtaining of coherent EMR are connected with development of free-electron lasers, which basic element is the undulator - the device for swinging of transverse oscillations of the RHCEB.

As distinct from the magneto-static, electrostatic and electromagnetic undulators, existing at present, the proposed acoustic undulator operates on the basis of the following principal.

As is known, the RHCEB propagation in neutral gases takes place within a range of pressures 1 - 40 mm Hg. With passage through neutral gas the RHCEB ionizes it, creating plasma. The plasma electrons quickly leave an occupied region of extent as affected of the electric field of a beam, and more inert positive ions will neutralize the beam on charge. Depending on a degree of neutralization the beam is stably propagated, perged or else when predominating the forces of magnetic compression - is tied together.

The electron beam, injected by the accelerator cathode, while passing through an anode foil, hits the drift tube filled with rarefied neutral gas. A sound source located in an opposite end face of the drift chamber, produces oscillations of a gas density along axis of the drift tube.

With the appropriate choice of a drift tube length and a super-sound frequency inside its the standing wave will be formed which will produce rarefaction and compression (nodes and anti-nodes) in gas, in consequence of which the degree of neutralization of the beam will vary.

If to assume, that when the definite pressure and degree of neutralization the beam stably drifts, when inserting the sound wave, passing nodes and anti-nodes, the beam will perge or compress alternatively, i.e. the sound wave will be a original undulator. The electron beam, interacted with periodical potential of plasma, generate the electromagnetic radiation.

The main objects of the given project are researches:


· behavior of the RHCEB, propagating in neutral gas, in which the intensive sound wave was excited;
· electromagnetic super-high-frequency (SHF) radiation, arising by reason of oscillations of the beam electrons in the acoustic undulator.

In this project a number of independent but interconnected problems are to be investigated:


· creation and development of theoretical model of phenomena, arising when moving the RHCEB in the acoustic undulator, including the program of numerical calculations;
· creation of an intensive sound wave in the drift tube;
· development of synchronization system and a control one for installation parameters;
· diagnostics of the SHF radiation and optimization of its parameters;
· investigation of the SHF-pulse formation in the waveguide system of the undulator.

As a result of the project realization:

1) the mathematical model of the interconnected phenomena, taking place in the acoustic undulator, will be constructed which operates with a wide choice of the undulator parameters (such as: current force, beam energy, length of a sound wave etc.);

2) the demonstrable sample of installation, generating the SHF radiation on the basis of the acoustic undulator will be created;

3) the characteristics of the obtained SHF radiation will be studied and the optimization methods of its parameters will be suggested.

The work in frame of the project will be completed by issue of the final scientific report and publications, including the whole file of received theoretical and experimental results.

In the last some years (from 1993) the theoretical research are conducted and some experiments under the decision of tasks put in the given project are carried out in IRPCP NASB. The results of these works were reported at the 8-th Russian conference on gravitation (Moscow, 1993) and stated in two preprints of IRPCP NASB. The participants of the project have the published works in scientific native and foreign journals, which confirm their appropriate knowledge and experience in the field theory, physics of electron beams, engineering of accelerators, acoustic and physics of plasma.

NPI had been created in 1986 year as a special scientific center for the execution of wide researches in FEL area and the developing (on the basis of Belarussion physicists discoveries) a new class of electromagnetic radiation generators - volume free electron lasers (VFEL) for Ministry of Defense USSR. Beginning at 70 years NPI scientists, under the guidance of Prof. Baryshevsky V.G., had executed the theoretical and experimental investigations of coherent radiation processes by different FEL schemes in the wide frequency range. As a result of these investigations are ground the creation of a principle new class of lasers - VFEL. These results had been published in Belarussian and international scientific journals and in the report on international FEL conferences.

A potential role of Foreign colloquies:

Foreign colloquies will be attracted to discussion of the work plan of the project and the results of researches.

We are ready to discuss the plans and results of researches and to cooperate with everyone, who will show interest to this work.


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