Speaker
Prof.
Alexander Shalashov
(Institute of Applied Physics RAS)
Description
In the present paper we target the physics of transition from subsonic to supersonic regimes in the expanding plasma flow. Originated form ECR ion sources, this problem is generalized to describe of the stationary highly-localized plasma discharge formed under resonant microwave heating in a gas jet freely expanding after a high-pressure nozzle. The peculiar feature of such a discharge is formation of a strongly non-equilibrium plasma flow with multiply charged ions and the electron temperature being much greater than the temperature of ions. We study possibilities for conjugating the slow movement of initially neutral dense gas and the supersonic flow of accelerated plasma, or, equivalently, a smooth transition from ion-acoustic barrier in the expanding flow with a varying charge state distribution. In such regimes, being of particular interest for applications, an average ion charge is consistently increased along the plasma flow, simultaneously the fraction of power losses due to line emission of highly charged ions is growing, and the emission spectrum is shifted to the shorter UV wave range. The proposed model is used to understand and optimize the recent experiments performed at IAP, Nizhny Novgorod, and aimed at demonstration of a new possibility of development of a point source of extreme ultraviolet radiation for the projective lithography. In these experiments, a line emission of multiply charged ions of noble gases has been investigated in the non-equilibrium discharge supported by high-power sub-millimeter waves in the expanding gas flow.
The work is supported by the Russian Science Foundation (project No 14-12-00609).
Primary author
Prof.
Alexander Shalashov
(Institute of Applied Physics RAS)
Co-authors
Dr
Egor Gospodchikov
(Institute of Applied Physics RAS)
Mr
Ilya Abramov
(Institute of Applied Physics RAS)
Prof.
Sergey Golubev
(Institute of Applied Physics RAS)
