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Sub-Thz Wave Generation by Plasma under High-Current Relativistic Electron Beam Impact in the GOL-PET Experiment

Name
Ivan
Surname
Ivanov
Scientific organization
Novosibirsk State University
Academic degree
Dr.Sc.
Position
Associate Professor
Scientific discipline
Physics & Astronomy
Topic
Sub-Thz Wave Generation by Plasma under High-Current Relativistic Electron Beam Impact in the GOL-PET Experiment
Abstract
Plasma emission in terahertz band during interaction of an intense relativistic electron beam with plasma is considerably interesting as bases for creation of high power generators. Strong plasma turbulence pumped by the beam at presence of magnetic field can generate EM-waves with frequencies close to upper-hybrid frequency and at its double value. To study this phenomena the specialized GOL-PET facility has been created with plasma Ne~10^15 cm-3 and the electron beam I~30 kA, E~0.6 MeV. Results of experimental studies of EM-wave generation will be presented in this paper.
Keywords
Summary

A.V. Arzhannikov1,2, A.V. Burdakov1, V.S. Burmasov1,2, L.N. Vyacheslavov1,2, I.A. Ivanov1,2, A.A. Kasatov1, S.A. Kuznetsov2, M.A. Makarov1, K.I. Mekler1, S.V. Polosatkin1,2, V.V. Postupaev1,2, S.L. Sinitsky1,2, V.F. Sklyarov1,2

1Budker Institute of Nuclear Physics, Novosibirsk, Russia

2Novosibirsk State University, Novosibirsk, Russia

In the paper, last experiment’s results on sub-THz wave emission from the area of relativistic electron beam-plasma interaction in the GOL-PET device are described [1]. A plasma column with the diameter of 6 cm, length of 2.5 m and its density (0.2-2) x1015 cm-3 is confined by multiple-mirror magnetic field with mean value of 4 T. The electron beam (REB) injected into the column, has the following parameters: energy Eb ~ 0.8 MeV, current Ib ~ 30 kA, current density Jb ~ 2 kA/cm2 in the mean magnetic field. Previous studies [2] have shown that the beam is pumping the plasma electron oscillations in a vicinity of the upper hybrid wave branch.  These plasma oscillations can be converted in electromagnetic waves on regular or artificial plasma density gradients (the plasma radiation with the upper hybrid frequency). The electromagnetic waves with the double upper hybrid frequency are also generated in the beam-plasma system due to coalescence of the plasma oscillations in case of high level of the oscillation energy density.

The described experiments are devoted to measure the spectral properties of the generated radiation and the directions of the sub-THz plasma emission in depending on plasma and beam parameters. As results of these experiments, the wave emission with the specific power concentrated in the direction along the axis of the plasma column, in the frequency interval 0.25-0.5 THz has been obtained at the plasma density about of 1015 cm-3.

This research was financially supported by RSCF under Project No. #14-12-00610 for the investigation of sub-terahertz emission from plasmas. The upgrade of the radiometric system was funded by the Ministry of Education and Science of RF under the State Assignment Contract No. #3002.

1. A. V. Arzhannikov et al., Dynamics and Spectral Composition of Subterahertz Emission From Plasma Column Due to Two-Stream Instability of Strong Relativistic Electron Beam // IEEE Trans. THz Sci. Technol., V6, N2, 245 (2016), doi: 10.1109/TTHZ.2016.2525783.

2. A.V. Arzhannikov et al., Observation of spectral composition and polarization of sub-terahertz emission from dense plasma during relativistic electron beam-plasma interaction// Phys. Plasmas, Vol. 21, No. 8, 2014, Art. ID 082106.