Particle-in-cell simulations of 100 keV electron beam interaction with a thin magnetized plasma

Annenkov, V. V.; Тимофеев, И. В.; Volchok, E. P.

doi:10.1063/1.4964235

Cited by 3 publications

(1 citation statement)

References 4 publications

(4 reference statements)

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“…Experimental spectra of the observed EM radiation as well as first PIC simulations for typical GOL-3 parameters [18] have shown that the fundamental and second harmonic emissions in these experiments have comparable integral powers. EM emission at the doubled plasma frequency in a thin beam-plasma system can be generated by nonlinear interaction of the most unstable beam-driven mode with satellite oscillations arising from scattering of the primary wave on the plasma density modulation: This nonlinear process has been already observed in PIC simulations [17], but it remains unclear how the efficiency of this radiation process depends on different beam and plasma parameters.…”

Section: Introductionmentioning

confidence: 75%

Second harmonic electromagnetic emission in a beam-driven plasma antenna

Annenkov

Berendeev

Volchok

et al. 2019

Plasma Phys. Control. Fusion

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Generation of electromagnetic radiation near the second harmonic of the plasma frequency during the injection of an electron beam into a rippled-density plasma channel is investigated using both analytical theory and particle-in-cell simulations. The generating scheme is based on nonlinear interaction of the most unstable beam-driven potential plasma wave with its satellite arising due to scattering on the longitudinal modulation of plasma density. Resulting superluminal oscillations of electric current in a finite-size plasma channel radiate electromagnetic waves via the same mechanism which has been recently studied for the fundamental harmonic emission and reffered as a beamdriven plasma antenna. It is shown that theoretical predictions for the optimal plasma width and modulation period are confirmed by simulation results and the power conversion efficiency of the second harmonic emission reaches several percent. Such an efficient mechanism opens the path to explanation of laboratory experiments with a thin electron beam at the GOL-3 mirror trap as well as to developing the scheme of terahertz generation at the gigawatt power level.

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Section: Introductionmentioning

confidence: 75%

Second harmonic electromagnetic emission in a beam-driven plasma antenna

Annenkov

Berendeev

Volchok

et al. 2019

Plasma Phys. Control. Fusion

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Simulations of a beam-driven plasma antenna in the regime of plasma transparency

2017

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In this paper, the theoretically predicted possibility to increase the efficiency of electromagnetic radiation generated by a thin beam-plasma system in the regime of oblique emission, when a plasma column becomes transparent to radiation near the plasma frequency, is investigated using particle-in-cell simulations. If a finite-size plasma column has a longitudinal density modulation, such a system is able to radiate electromagnetic waves as a dipole antenna. This radiation mechanism is based on the conversion of an electron beam-driven potential plasma wave on the periodic perturbation of plasma density. In this case, the frequency of radiated waves appears to be slightly lower than the plasma frequency. That is why their fields enable the penetration into the plasma only to the skin-depth. This case is realized when the period of density modulation coincides with the wavelength of the most unstable beam-driven mode, and the produced radiation escapes from the plasma in the purely transverse direction. In the recent theoretical paper [I. V. Timofeev et al. Phys. Plasmas 23, 083119 (2016)], however, it has been found that the magnetized plasma can be transparent to this radiation at certain emission angles. It means that the beam-to-radiation power conversion can be highly efficient even in a relatively thick plasma since not only boundary layers but also the whole plasma volume can be involved in the generation of electromagnetic waves. Simulations of steady-state beam injection into a pre-modulated plasma channel confirm the existence of this effect and show limits of validity for the simplified theoretical model.

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Highly efficient electromagnetic emission during 100 keV electron beam relaxation in a thin magnetized plasma

2019

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In this paper, electromagnetic emissions produced by a beam-plasma system are investigated using particlein-cell simulations for the particular case when the typical transverse size of both 100 keV electron beam and produced plasma channel is comparable to the radiation wavelength. The interest in this regime of beamplasma interaction is associated with highly efficient generation of electromagnetic waves near the plasma frequency harmonics that has been recently observed in laboratory experiments on the GOL-3 mirror trap. It has been found that the radiation power only from the vicinity of the doubled plasma frequency in these experiments can reach 1% of the total beam power. Subsequent theoretical and simulation studies have shown that the most likely candidate for explaining such efficient generation of electromagnetic radiation is the mechanism of a beam-driven plasma antenna based on the conversion of the most unstable plasma oscillations on a longitudinal density modulation of plasma ions. In this paper, we investigate how effectively this mechanism can work in a real experiment at the GOL-3 facility, when a thin sub-relativistic electron beam gets a large angular spread due to compression by a magnetic field, and the gas into which it is injected has macroscopic density gradients.

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Particle-in-cell simulations of 100 keV electron beam interaction with a thin magnetized plasma

Cited by 3 publications

References 4 publications

Second harmonic electromagnetic emission in a beam-driven plasma antenna

Second harmonic electromagnetic emission in a beam-driven plasma antenna

Simulations of a beam-driven plasma antenna in the regime of plasma transparency

Highly efficient electromagnetic emission during 100 keV electron beam relaxation in a thin magnetized plasma

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