The Behaviour of Population in a Plasma Interacting with an Atomic Gas

Abstract

The processes leading to the population inversion are investigated in a recombining hydrogen plasma which is interacting with a cool and dense neutral hydrogen gas by using the rate equations on the basis of a collisional-radiative (CR) model and the energy equations for electrons, ions and neutral particles. The quasi-steady state (QSS) approximation is used only for the levels i lying above a certain level /* which is not the first excited level. The calculations have shown that the quasi-steady state cannot be realized while intense energy-flows due to the collisional processes exist between different kinds of the particles such as the electrons and the ions in the plasma, and that the population inversion is realized only in the quasi-steady state following the transient phase. The effects of the initial conditions of the hydrogen plasma and of the introduced neutral hydrogen gas on the overpopulation density are also discussed.

Initial Condition and Cooling Time of Recombining Helium Plasma for Stationary VUV Lasing Action

“…trons with heavy particles as shown by Furukane and Oda, and Oda and Furukane [16,17]. Nam et al [18] have pointed out that radiation cooling leads to simi lar decay times.…”

Stationary Population Inversion in an Expanding Argon Plasma Jet by Helium Puffing

“…On the other hand, the decrease in T e of case B from z = 8 to z = 22 cm is reduced to 0.04 eV. This reduction of electron cooling can be explained on the basis of energy balance equation for electrons [9]. As we specify in the next chapter, electron temperature is temporally traced by the energy balance equation describing the energy increase of electrons per unit time [10].…”

Numerical Investigation of Laser Oscillation in a Recombining Hydrogen Plasma Interacting with Helium Gas in TPD-I

“…In a previous paper [4] we have investigated the processes leading to the population inversion between the levels with the principal quantum numbers 3 and 4 in a recombining hydrogen plasma which is interacting with a cool and dense neutral hydrogen gas by using the rate equations on the basis of a collisional-radiative (CR) model and the energy equations for electrons, ions and neutral particles.…”

“…In order to realize laser action between the levels 2 and 3 we can simply use an other neutral gas, for example helium instead of hydrogen to cool the high temperature hydrogen plasma as pointed out in [4],…”

“…In the present paper, we investigate laser oscillation between the levels 2 and 3 in a recombining hydrogen plasma which is interacting with a dense helium gas by using the same method as that in [4].…”