Speaker
Dr
Egor Gospodchikov
(Institute of Applied Physics RAS; BINP SB RAS)
Description
Microwave heating of electrons under the electron cyclotron resonance conditions is one of the most efficient ways to increase the electron temperature of magnetically confined plasmas. Recent pprogress plasma confinement in axially symmetric magnetic traps led to the achievement of regimes, in which the ratio between plasma pressure and the magnetic field pressure ($\beta$) can be of the order of unity. Under these circumstances the Langmuir plasma frequency is much greater than the electron cyclotron frequency, $\omega_p\gg\omega_b$. Therefore, the use of common schemes of electron cyclotron heating based on direct launch of electromagnetic waves from the vacuum window meets obvious difficulties because the resonance region is screened by dense plasma for all electromagnetic modes except waves propagating strictly along the external magnetic field. However, in many cases strictly longitudinal propagation is not technically possible. One way to overcome this problem is to use the linear transformation of electromagnetic waves in quasi-electrostatic plasma oscillations in the vicinity of the plasma resonance. Once exited, the quasi-electrostatic oscillations can be effectively damped by electrons, in particular, in plasmas with $\omega_p\gg\omega_b$.
The transformation of electromagnetic waves in quasi-electrostatic waves under condition of a high-$\beta$ open trap, $\omega_b\ll\omega_p\approx\omega$ shows a number of peculiar features which significantly distinguish this process both from the case a strong magnetic field $\omega_B\approx\omega_P$, which is used for heating of a dense plasma in low-$\beta$ devices, and from the well-known case of Langmuir wave coupling in an isotropic medium with $\omega_b=0$. The present work is devoted to the theoretical study of these features.
The work is supported by the Russian Science Foundation (project No 14-12-01007).
Primary author
Dr
Egor Gospodchikov
(Institute of Applied Physics RAS; BINP SB RAS)
Co-authors
Prof.
Alexander Shalashov
(Institute of Applied Physics RAS; BINP SB RAS)
Mr
Anton Kutlin
(Institute of Applied Physics RAS)
