Speaker
Ms
Evgeniya Volchok
(Budker INP SB RAS, NSU)
Description
The problem of electromagnetic radiation from plasma near the plasma frequency and its second harmonic has been actively studied for decades. At this moment, there are many different approaches to this problem. However, most of them assume that the plasma size significantly exceeds the wavelength of generated radiation. Our interest to this problem is motivated by the experiments on the electron beam interaction with a thin magnetized plasma at the GOL-3 mirror trap. It has been found that the radiation efficiency in these experiments can reach 1% [1].
In this work, we formulate the theory of electromagnetic emission near the plasma frequency for the case of the finite-size beam-plasma system typical to laboratory experiments. If the density of a thin plasma column is modulated along the magnetic field, such a system can radiate like an ordinary antenna. It has been recently shown that, in the simplified case of a plane plasma slab in which the period of density modulation equals to the wavelength of the most unstable beam-driven mode, theoretical predictions are confirmed by particle-in-cell simulations [2-3]. To describe the turbulent regime with the wide spectrum of density perturbations, we generalize our theoretical approach to the arbitrary lengths of longitudinal density modulation and calculate the power of electromagnetic radiation in the more realistic cylindrical geometry. It is shown that the most efficient radiation can be generated for those modulation lengths at which the plasma becomes transparent for the radiated electromagnetic waves.
This work is supported by RFBR (grant 15-32-20432) and the Russian Scientific Foundation (grant 14-12-00610).
1. A.V.Burdakov et al. , Fusion Sci. Technol. 63 (1T), 286 (2013).
2. I.V. Timofeev, V.V. Annenkov, A.V. Arzhannikov, Phys. Plasmas 22, 113109 (2015).
3. V.V.Annenkov, E.P.Volchok, I.V.Timofeev, Plasma Phys. Control. Fusion 58, 045009 (2016).
Primary author
Ms
Evgeniya Volchok
(Budker INP SB RAS, NSU)
Co-authors
Dr
Igor Timofeev
(Budker INP SB RAS)
Mr
Vladimir Annenkov
(Budker INP SB RAS)
