The two-photon absorption laser induced stimulated emission as a hydrogen atoms diagnostic tool: modelling and experiment

A modelling of the two-photon absorption laser induced stimulated emission (TALISE) as a technique for the ground state hydrogen atom detection is pre sented. The numerical results are validated by comparison with experimental results obtained in hydrogen low-pressure discharge. The discharge conditi ons studied are: pressure from 0.5 until 5.0 Torr and current between 1 and 50 mA. The predictions of the model are used to establish the conditions o f experimental parameters allowing the use of the TALISE effect as diagnost ic tool when the length of the focal lens, that focuses the probe laser bea m, varies from 15 until 45 cm and the energy of the laser probe changes fro m 0.1 until 2.0 mJ. It was shown that as a function of discharge parameters , i.e. current and pressure, the H atom density threshold for TALISE onset varies from 8 x 10(12) until 6 x 10(13) cm(-3). (C) 2001 Elsevier Science B .V. All rights reserved.