Gain limitations in CO2 lasers

Mellis, J.; Smith, A L S

doi:10.1016/0030-4018(82)90331-5

Cited by 10 publications

(4 citation statements)

References 11 publications

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“…No indications of the saturation of the temperature T 3 with increase in the pumping energy W p were noted. The high values of the gain coefficient and T 3 are attributed in [16] to the absence of the mechanism of de-excitation by electrons of the upper laser level 00 0 1 in an optical-pumping system, and these results are considered as confirmation of the earlier conclusion [5][6][7][8][9][10] that precisely the de-excitation by electrons restricted the excitation of the ν 3 mode and, consequently, also amplification in electricdischarge CO 2 lasers.…”

Section: Introductionsupporting

confidence: 69%

“…It is seen that for the same quantity of vibrational energy expressions (3) and (8) put into correspondence different values of the vibrational temperature T 3 , with formula (3) yielding a lower value of T 3 in comparison with that given by Eq. (8). The use of these data together with the measured gain coefficient leads to understated values of the vibrational temperatures T 1 and T 2 and, as a consequence, to incorrect interpretation of the physical processes proceeding in the active medium [14].…”

Section: Introductionmentioning

confidence: 99%

“…According to [5][6][7][8][9][10]13], the temperature T 3 measured by different methods is saturated in both a continuous and a pulsed discharge. Based on experimental results, a conclusion was drawn in [10] that there was a certain fundamental restriction on the value of T 3 in electric-discharge CO 2 lasers that prevented T 3 from attaining values higher than 2000-3000 K depending on the composition of the mixture.…”

Section: Introductionmentioning

confidence: 99%

“…In the literature (see, e.g, [4][5][6][7][8][9][10][11][12][13]), quantities that are called the occupation numbers of modes e i or the numbers of vibrational quanta in a mode per molecule are used. In this case, each of the vibrational modes of the CO 2 molecules is considered as an independent harmonic oscillator, so that for the quantities e 1 -e 4 the following expressions are used:…”

Section: Introductionmentioning

confidence: 99%

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Vibrational kinetics of the active media of CW CO2 lasers

Невдах

Ganjali

2005

J Appl Spectrosc

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The vibrational kinetics of CW CO 2 lasers has been analyzed within the framework of a temperature model. The necessity of taking into account the coupling of the vibrational modes of the CO 2 molecule in determining the occupation numbers and the store of vibrational energy in individual modes is shown. Expressions that connect vibrational temperatures with the rates of excitation and relaxation of the lower vibrational levels of modes have been obtained. The ratios between the vibrational temperatures on selective excitation of the 00 o 1 level and on excitation of CO 2 molecules in an electric discharge as well as the character of the dependences of vibrational temperatures on the pumping-energy value are discussed. Introduction.The most widespread mathematical model used for calculating the energy and spectral characteristics of continuous wave and pulsed (with pulse duration longer than 10 −6 sec) CO 2 lasers is a temperature model. Physically, the model is based on the "hierarchy" of relaxation times that is typical of the CO 2 molecule under the conditions of an active medium:are the times of rotational-translational, vibrational-vibrational intramode, vibrational-translational, and vibrational-vibrational intramode relaxation, respectively (see, e.g., [1][2][3][4]). Within the framework of the temperature model, the vibrational modes ν 1 , ν 2 , and ν 3 of the CO 2 molecules and ν 4 of the N 2 molecules are considered as simple harmonic oscillators. The distributions of populations over the vibrational levels of each of these modes are described by the Boltzmann distributions with vibrational temperatures T i (i = 1, 2, 3, 4). Knowing the vibrational temperatures, it is possible to determine the population of any vibrational level of the CO 2 and N 2 molecules and also the stores of vibrational energy in their modes. The main drawback of this approach is that the vibrational modes of the CO 2 molecule are considered as independent modes, whereas the vibrational temperatures of these modes are regarded as independent parameters.In the present work, within the framework of the temperature model we analyze the vibrational kinetics of continuously pumped CO 2 lasers taking into account the fact that because of the coupling of the vibrational modes of the CO 2 molecule the vibrational temperatures are not independent parameters.Occupation Numbers of the Vibrational Modes of the CO 2 Molecule. In the temperature model the vibrational temperatures of the CO 2 and N 2 molecules are determined [1-4] from the conditions

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