Serna Galán, JulioEncinas Sanz, FernandoMartínez Herrero, María RosarioMartín Mejías, Pedro2023-06-202023-06-202001-071084-752910.1364/JOSAA.18.001734https://hdl.handle.net/20.500.14352/58582© 2001 Optical Society of America. This work was supported by the Comisión Interministerial de Ciencia y Tecnología of Spain under project PB97-0295.The evolution of the intensity profile of transversely excited atmospheric CO_2 laser pulses is investigated within the intensity moment formalism. The beam quality factor M_2 is used to study the mode evolution. Attention is focused on the influence of both the gas mixture (N_2:CO_2:He) and the diameter of an intracavity diaphragm placed to attenuate higher-order modes. The degree of accuracy that can be attained by approximating the laser field amplitude by means of the lower-order terms of a Hermite-Gauss expansion is also analyzed. In particular, a bound for the truncation error is given in terms of two time-resolved spatial parameters, namely the beam width and the M_2 parameter.engjournal articlehttp://dx.doi.org/10.1364/JOSAA.18.001734http://www.opticsinfobase.orgopen access535Partially Coherent BeamsParametric CharacterizationEvolutionCO_2-LaserLightÓptica (Física)2209.19 Óptica Física