SF<sub>6</sub> and C<sub>2</sub>H<sub>6</sub> are the working gas mixture of non-chain HF laser. In our work, we use a simple pumping circuit to study the influence of the electric field uniformity on the discharge characters. Three groups of electrodes with different designs have been manufactured, and different discharge characters have been got. We have analyzed the results qualitatively, and find that without preionization, uniform electric field is not the best choice to form a large volume discharge in strong negative gas such as SF<sub>6</sub>-based mixture; approximate uniform electric field may be its substitution. In such electric field the gap breakdown voltage decreases and discharge can perform much easily. The discharge channels away from the cathode surface can also diffuse together to form a large volume discharge to deposit the electric energy into the laser working gas.
The investigations of the XeF laser bumped by ultraviolet radiation have been studied for more than 20 years in Northwest Institute of Nuclear Technology (NINT Xi’an China). Up to now, several XeF laser devices were developed and an integrative experimental system has been set up which is comprised of a laser device, an electrical power supply, a high voltage trigger generator and a mixture gas supply device. Many key technologies were studied in detail and have been applied now. These technologies include section surface discharge, XeF2 photodissociation, synchronal trigger generating, double-sides optical pumping from opposite directions, active mixture gases supplying in real time, gases circulation, and so on. The XeF laser system operating on pulse repetition frequency (PRF) is up to 10 Hz. Two kinds of operating modes were applied. For the open gas flowing mode, the pulse energy of 3.2 J and the average power of 32 W at 10Hz is obtained. For the gases circumrotate mode, the average energy of 20 laser pulses is more than 0.5J.
This paper presents the results of studies on high power photochemical XeF(C-A) laser with repetition mode. A new design of optical pumping source is proposed and the deposition efficiency is higher than 75 %. The form process and the temporal and spatial characteristics of the XeF<sub>2</sub> photodissociation wave are studied experimentally. The results indicate that when the deposition power is 12.5 MW/cm, the maximum brightness temperature reaches more than 25 kK and the photon flux obtained more than 4×10<sup>23</sup> photon s<sup>-1 </sup>cm<sup>-2</sup> in the VUV range of 130 nm~180 nm. A novel XeF(C-A) laser which can be operated in repetition mode has been developed based on surface discharge optical pumping technique. The ideal output energy results of 20 laser pulses are presented under different repetitive rates and their optimal experimental conditions. Output energies of more than 4J and better stability can be obtained when the laser device operates at 1, 2 and 5 Hz, respectively. When the gas feed rate is larger than 53L/s, the average energy of 20 laser pulses is up to 3.2J at the repetitive rate of 10Hz. The technology for the laser spectral narrowing is studied.
The design and performance of a closed cycle, repetitively pulsed HF laser is described. The homogeneous glow discharge is formed with UV pre-ionization and transverse discharge structure. The optimal output parameters of single pulse operation are given by the investigation of discharge characteristics in SF<sub>6</sub> /C<sub>2</sub>H<sub>6</sub> gas mixture and output characteristics of laser pulse. The repetitively pulse energy stability of laser device are checked with different conditions of gas flowing velocity, charging voltage and total pressure of gas mixture. It is shown that the maximal output energy of laser pulse of 0.6J, peak power 3MW are obtained. Total efficiency of laser device is about 2.4%. When the gas mixture circulating with 4m/s flowing velocity, the maximal running frequency of 50Hz are obtained and operating stability keep well. Under these conditions, the laser pulse energy keeps stable and the average output power is 18W.
The output energy stability of discharged-pumped pulsed HF laser in repetition rate mode is
studied experimentally, and the optimal operating conditions are obtained. The experimental
results show that the output energy decreases quickly with the increase of repetition rate, and
increasing gas flow rate is beneficial to improve the discharge stability and the output energy
stability as well. By optimizing the operating conditions, the laser can operate stably at the
repetition rate of 50 Hz, with the stable output energy of about 260 mJ, and the average power is
about 13 W.
Surface discharge Radiation Source has been used as optical pumping source of XeF(C-A) gaseous laser. In
previous works, discharge deposition power, transition efficiency and UV radiation intensity of surface discharge
Radiation Source were mostly concerned, but the jitter of repetitively pulsed surface discharge was little studied. An
optical pumping source by segmented surface discharge on Al<sub>2</sub>O<sub>3</sub> ceramic substrate is developed to design stable
XeF(C-A) laser with pulse repetitive mode. Distorted electric field near the surfaces of the ceramic substrate is calculated
based on equivalent chain circuit model under conditions of charging voltage from 0 to 26.8kV, thickness of the substrate
from 1mm to 3mm, and trigger pulse voltage from 47kV to 63kV. Analysis about trigger characteristics of pumping
source is carried out, and influence of these conditions on discharge jitter is discussed. And discharge jitter is investigated
in detail under different conditions. The experimental results show that discharge jitter decreases with increasing
charging voltage and trigger pulse voltage, as well as decreasing thickness of ceramic substrate, and the pulse repetition
rate has little influence on the discharge jitter in the range of 1Hz to 30Hz. These experimental results are coincident with
numerical simulation results. Normally, the discharge jitter can be less than 30ns. Research results indicate that the
optical pumping source has good time stability of repetitive pulse discharge.