TEA nitrogen laser
A Transversely Excited Atmospheric (TEA) nitrogen laser is a pulse mode molecular gas laser. In this arrangement, the whole volume of the gas is excited by a single electric pulse. Normally, N2 gas or air is being used as an active medium in TEA nitrogen laser, and lasing is obtained through electrical discharge of N2 gas or air between two specifically designed electrodes. An ignition system obtains a high potential difference in the laser discharge channel creates a strong electric field in the laser discharge channel which excites the nitrogen molecules because of the fast pumping mechanism from the ground state to the Upper laser level. Population inversion established between the upper laser level and the lower laser level by electron impact excitations. The laser transition occurs by emitting photons in ultraviolet (UV) region corresponding to the transitions from upper laser level to lower laser level. Nitrogen laser has been used to measure the speed of sound in different materials, and to visualize the pulse plasma in the nanosecond range. It has applications in medicine, determination of estrogens using surface-assisted laser desorption, nano-particles based mass spectrometry for biomolecules analysis, deposition of thin films for nonlinear optical applications and characterization of phase change chalcogenide thin film.
TEa nitrogen laser electronics and intrumentation
Nitrogen lasers are a source of coherent ultraviolet light, which operates in pulse mode both at high pressure and at low pressure. The nitrogen laser that runs at atmospheric pressure is termed as transversely electrical excited atmospheric (TEA) pressure nitrogen laser. In the TEA nitrogen laser electrodes are set to be used for traveling wave excitation in the transverse mode of operation rather than the longitudinal arrangement because of their high delivering output power, efficient and faster voltage rise time. The Blumlein line discharge circuit or charge transfer circuit uses for the operation of this laser. A free running spark gap (SG) or spark plug uses for the triggering of the laser system that transfers the electrical energy to the laser channel, which excites the air molecules in a time scale of few nanoseconds. In general, TEA nitrogen lasers operated at a voltage in the ranges of (5–40) kV with the output energies from 40 to 370 µJ with the pulse duration ~ 1.5 ns.