Theory of the Pulsed Molecular Nitrogen Laser

Abstract

It is shown that laser action at 3371 A terminates in times t < (tau(32)(-1) + Y(3))(-1), where tau(32) is the lifetime of the transition of C(3)pi(u) --> B(3)pi(g) and Y(3) is the electron depopulation rate of the upper laser level. Following Gerry but including electron impact mixing of laser levels, rate equations, coupled to the circuit equation, were solved under saturation approximations. Assuming a Seaton excitation cross section between laser levels, with an effective Gaunt factor of 0.25, power and pulse width were in good agreement with Shipman's values. The rate equations were also solved without recourse to the saturation approximation yielding excellent agreement with the saturation method during most of the pulse and indicating the existence of an early oscillation which is not predicted by the saturation approximation method. Finally, the inclusion of the electron impact ionization of he nitrogen molecule from the excited state C(3)pi(u) brings the pulse width to still better agreement with Shipman's values.

Time-resolved analysis of a transversely excited nitrogen laser

“…1,25]. The other equations are in accordance with [10,11]. rotational laser levels and N+ and N_ the number densities of photons travelling in the positive and negative direction, g3 and g2 are the statistical weights of the upper and lower laser levels, given by (2J + 1), where J is the rotational quantum number.…”

“…The problem of calculating the excitation rates to the laser levels in the nitrogen laser has been dealt with in [9][10][11]16]. In the present work two methods were used in accordance with [16].…”

“…In the present work two methods were used in accordance with [16]. One method, based on electrical measurements, resembles the outlines in [9][10][11], although the detailed approach is different, including the use of more recent cross-section data. The other method is based on measurements of spontaneous emission.…”

“…References [1][2][3][4][5][6][7][8] describe transversely excited nitrogen lasers. Nitrogen laser theory is dealt with in [9][10][11] and spectroscopy on the stimulated emission may be found in [12,13].…”

“…We therefore present detailed measurements on a simple transversely excited nitrogen laser of moderate power, due in principle, to . Further, a simple theory, mainly in the spirit of Gerry I-9] and All 9 1974 Chapman and Hall Ltd. et al i- 10,11], but with certain extensions, is presented along with numerical results and comparisons with measurements.…”