High average power XeCl and pulsed HF chemical lasers

NO removal in a photo-triggered discharge reactor

“…In 1982, a new discharge scheme was proposed [20] in which the order of operations is just reversed. In this technique, the so-called photo-triggered pumping scheme [20][21][22][23][24][25][26][27][28][29][30], the discharge electrodes are directly connected, without any high-power switch, to an energy storage unit which is pulsed charged up to a voltage V capa . The initial voltage V capa is chosen so that the initial reduced electric field (E/N ) 0 , defined by the relation (E/N ) 0 = V capa /N d where N is the number density of the gas mixture and d the inter-electrode gap, is a factor of two above the steady-state voltage.…”

“…First, the removal of the high-power switch greatly increases the lifetime and the reliability of the laser. As a result, in industrial photo-triggered lasers working at pulse repetition rate frequency higher than 500 Hz [28], more than 10 9 shots can be reached without major problem [29]. Second, the seeding in pre-ionizing electrons after the voltage has reached twice the self-sustaining voltage results in more homogeneous discharges with lower requirements on the pre-ionizing device.…”

“…Second, the seeding in pre-ionizing electrons after the voltage has reached twice the self-sustaining voltage results in more homogeneous discharges with lower requirements on the pre-ionizing device. Better laser efficiencies have been achieved both in chemical [26,30] and excimer [25,[27][28][29] lasers for which the photo-triggering technique has been fully implemented.…”

“…An examination of the physical problems linked to the production of large, homogeneous and reactive cold plasmas in high pressure conditions points out that they are quite similar to those met and solved since the last ten years in the development of high-power excimer or pulsed chemical lasers energised by electrical discharges. Among the different techniques investigated to achieve highperformance lasers, the so-called photo-triggered discharges have been proved a simple and reliable excitation means for the development of high-power lasers [20][21][22][23][24][25][26][27][28][29]. This discharge technique allows us to uniformly inject high energy densities (100-1000 J l −1 ) into large volumes (up to 10 litres) of gas and to initiate the complex reactional channels leading to the formation of the upper level of the laser transitions.…”

“…This discharge technique allows us to uniformly inject high energy densities (100-1000 J l −1 ) into large volumes (up to 10 litres) of gas and to initiate the complex reactional channels leading to the formation of the upper level of the laser transitions. To achieve best performances, the laser gas mixture should be replaced between each shot, which leads, for industrial lasers working at a repetition rate of about 1 kHz, to handling gas flow rates in the range of several cubic metres per second [28] which is far beyond the possibilities of the DBD or pulsed corona discharges. In that respect, only one phototriggered reactor could replace many conventional reactors working in parallel.…”