Surface plasma preionization produced on a specially patterned PCB and its application in a pulsed CO2 laser

Comparative study of spark pin-array and printed circuit board surface plasma pre-ionization systems for transversely excited atmospheric CO2 laser performance

“…However, the highest values for discharge voltage, main capacitance and repetition rate, implying stable glow discharges in SPA pre-ionized active volume, do not exceed 31 kV, 33.3 nF and 1 Hz, respectively. This behavior can be explained based on some structural and physical differences between these pre-ionization systems as follows: (a) Due to the geometry condition, the UV radiation produced by the patterned PCB covers the discharge volume more efficiently and effectively than that is emitted by the array of the peripheral spark gaps; (b) the uniform surficial plasma created on the PCB can provide additional help to glow discharge by growing towards the anode electrode; (c) in contrast to the high-density lowenergy electrons generated in spark discharges which are very efficient in dissociating CO 2 molecules through vibrational excitation, the low-density high-energy electrons produced in surface discharges are not so effective in dissociation of CO 2 molecules through vibrational as well as electronic excitations [16]; (d) these high-energy electrons shift the spectrum of the relevant radiation towards the UV region suitable for photoionization of the CO 2 lasers gas mixtures, thereby creating higher photo-electron densities in the active volume than those produced by the spark-induced radiation [20].…”

“…Recently, a new construction of pre-ionization system, the so-called printed circuit board (PCB) surface plasma cathode, has been introduced [16] in which a specially patterned nonprofiled flat double-side PCB plays the role of the main electrode and the pre-ionization system simultaneously [16]. Since this novel configuration seems to be very promising, especially for high repetition rate and sealed-off CO 2 laser systems, in this work, a series of experiments are performed in detail to characterize its performance in comparison to the familiar SPA pre-ionization method.…”

Performance of a surface corona preionized mini-TEA CO2 laser

“…With a gas mixture of 1:1:3 (CO 2 :N 2 :He) and gas pressure of 1.0 bar, the discharge voltage reaches a maximum value of 24.2 kV with a rise time (10%-90%) of approximately 92 ns (figure 3(a)). The laser pulse shape consists of an initial spike induced by gain-switching, followed by a slowly decaying tail which is an indicative of the degree of vibrational excitation of nitrogen molecules [26]. The output pulse energy contained in the spike was 195 mJ with a pulse duration (FWHM) of 73 ns.…”

Some experimental studies on the UV spark pin-array pre-ionization in TEA CO2 laser

“…These lasers provide output pulses in 9-11 µm spectral range with energies up to several kJ [1,2], time durations varying from ps [3] to µs [4] orders and repetition rates up to several kHz [5] with relatively low costs and without the needs for high-tech facilities. This flexibility in output characteristics are due to novel developments and progresses in various aspects including discharge circuits [6-8], electrodes [9-12] and resonator [13, 14] configurations, gas mixture [15][16][17] and pressure [18][19][20], pulse shaping techniques [21] as well as pre-ionization methods [22][23][24][25][26]. Each of these items plays a key role in achieving stable and longterm operation of the laser especially at high repetition rates and sealed-off regime [27][28][29].…”