Population inversion between the ground and first excited states in a recombining hydrogen plasma

Numerical Study on Population Inversion and Lasing Conditions in an Optically Thick Recombining Helium Plasma

“…= neniz(P) 3 (8) where gi is a statistical weight of the ion, h the Planck constant, m the electron mass, k the Boltzmann constant, and ~( p ) the ionization potential of level p. Z(p) is referred as the Saha factor [21].…”

“…The partial pressure of the neutral helium in the discharging region P,, is then estimated at 2.7 x 104-6.5 x lo4 Pa. The Doppler blueshift is monitored [26] and it tells us that the mean velocity of the pure helium plasma jet is -5 With this apparatus, we can generate the helium plasma where T, z 0.08-0.5 eV and n, z 1.0 x 10'2-2.0 x 1013 cm-3 with the background helium pressure P,, [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] in the plasma expansion area [24,251. We can measure the population densities of the excited states with a principal quantum number N 2 3 by spectroscopic observations with a monochromator calibrated absolutely [26].…”

Spectroscopic study of ionizing and recombining plasma in a stationary plasma source

“…A numerical calculation derived from a collisional radiative model shows that a significant high electron density, м10 16 cm Ϫ3 might be needed for the lasing action. 7,8 Atomic and molecular processes in high density, low temperature plasmas have been also studied extensively in TPD apparatus. [9][10][11][12] As an example, selective double electron capture process of He 2ϩ ion in contact with a hydrogen molecule, He 2ϩ ϩH 2 →He*(1s3l)ϩ2H ϩ , was found to have a large cross section in a low energy collision.…”

High‐speed numerical calculation method for rate equations of abruptly recombining plasmas

“…In earlier states, the population inversion between the excited states was investigated [1,2]. Recently, it was suggested that the population inversion between the ground and the first excited states is possible in a rapidly cooling highdensity plasma [3,4] . In a theoretical investigation of population inversion, the population density is evaluated by numerically solving the rate equations on the basis of the collisional radiative (CR) mode [5,6], where the collisional and radiative phenomena from all the excited levels are taken into account.…”

“…We have investigated the optimum plasma parameters and cooling condition for the lasing action , which is realized by using the population inversion between the ground and the first excited states of a hydrogen plasma [4] and the one between the levels 2 + and 3 of the helium ion He [8]. It was found that rapid var iation of electron density was needed for the population inversion and the laser oscillation to be realized.…”