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

Furukane, Utarô; Tsuji, Yasumasa; Oda, Toshiatsu

doi:10.1515/zna-1988-0403

Cited by 5 publications

(2 citation statements)

References 15 publications

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“…We have already investigated the behaviour (case A) of gas-contact cooling of a recombining hydrogen plasma with zero mixing time in a previous paper [ 161. However, no examination has been presented on the effect of a finite mixing time as given in cases B and C. A strong overpopulation density may be produced in the initial plasma in case C because it has the optimum initial density as found in the calculation of our previous paper [29] in which it was assumed that the electron temperature T, changes with finite decay time tE. for 0 S ts T,,, and n, for t > s,ix.…”

Section: Numerical Results and Discussionmentioning

confidence: 93%

Simulation of gas-contact cooling for VUV laser oscillation in recombining plasmas

Furukane¹,

Sato²,

Oda³

1989

J. Phys. D: Appl. Phys.

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Possible rapid cooling of a higher temperature plasma is investigated in a gas-contact cooling method in which the effect of finite time for mixing the plasma and the contact gas is considered. The calculation has shown that cooling under these conditions is much more rapid than that achieved by radiative loss cooling and that the gain per unit length of the He II 164 nm line is approximately 2 cm-1 for the laser oscillation under optimum conditions. The possibility of realising a laser at a shorter wavelength in a plasma with higher charge number Z is also discussed.

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Section: Numerical Results and Discussionmentioning

confidence: 93%

Simulation of gas-contact cooling for VUV laser oscillation in recombining plasmas

Furukane¹,

Sato²,

Oda³

1989

J. Phys. D: Appl. Phys.

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“…The development of the ionization and recombination phases in the plasma can be studied numerically by solving a combined set of differential equations for energy balance in the plasma and for the temporal evolution of electron and ion densities as well as the population density in each energy level. [7][8][9] These combined differential equations are nonlinear and difficult in general to solve numerically when conditions in high-density plasmas change rapidly, because the integration requires central processing unit (CPU) times which are too long. The usual quasi-steady-state (QSS) approximation 10) may be violated for the excited levels in such plasmas.…”

Section: Introductionmentioning

confidence: 99%

Fast Numerical Calculation for a Set of Nonlinear Rate Equations: Application to Rapid Ionizaton Phase in Plasma

Oda¹,

Namba

Takiyama

et al. 2005

Jpn. J. Appl. Phys.

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To make a useful contribution to the development of the compact X-ray laser, a modified quasi-steady-state approximation is applied to the fast numerical calculation of rate equations for the rapid ionization phase of a laser-produced plasma, to which the usual quasi-steady-state model by Bates et al. is not applicable. The set of nonlinear rate equations for the excited level populations coupled with the electron density and temperature for the plasma are numerically calculated with sufficient accuracy for their temporal evolution. The calculation also shows that a suitable combination is possible between the power and pulse width of a heating laser so that a high-density plasma can be obtained as the X-ray laser medium. The mathematical meaning of our approximation is briefly mentioned and its applicability is discussed.

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Population Inversion in a Recombining Helium Plasma Mixing with Hydrogen Molecular Gas in a TPD-I Machine

Furukane

Sato

Oda

1990

Jpn. J. Appl. Phys.

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A high potentiality of plasma cooling and its mechanism are theoretically revealed for a helium plasma which comes into contact with hydrogen molecular gas in the TPD-I machine. The stationary population inversion between the levels n=2 and 3 of the He+ ion, which is due to mixing of the stationary high-temperature helium plasma and the hydrogen molecular gas, is simulated and discussed in comparison with cooling due to the mixing of the plasma and the atomic hydrogen gas. The calculation also shows that the gain per unit length of the He II 164 nm line is ∼ 2 cm-1 for the laser oscillation under optimum initial helium plasma (T e ∼ 30 eV and n e ∼ 3.5 × 1016 cm-3) contacted with hydrogen molecular gas at a pressure of 0.1 Torr.

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

Abstract: I n itia l C o n d itio n a n d C o o lin g T im e o f R e c o m b in in g H e liu m P la s m a fo r S t a ti o n a r y V U V L a s in g A c tio n

Cited by 5 publications

References 15 publications

Simulation of gas-contact cooling for VUV laser oscillation in recombining plasmas

Simulation of gas-contact cooling for VUV laser oscillation in recombining plasmas

Fast Numerical Calculation for a Set of Nonlinear Rate Equations: Application to Rapid Ionizaton Phase in Plasma

Population Inversion in a Recombining Helium Plasma Mixing with Hydrogen Molecular Gas in a TPD-I Machine

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