[en] In order to achieve three-step pulse shaping (time proportion 1.5 ns:1.0 ns:0.5 ns, power proportion 1:4:16, total energy 500 J) required by the physical experiments on Shenguang-III technical integration experimental line (TIL), some researches on waveform control of high power laser pulse shaping have been done on the basis of TIL system structure and the technology which can form arbitrary pulse waveform. By analyzing gain saturation effect and frequency conversion process, the paper gets the pulse change in transmission, amplification and frequency conversion processes, and builds a simple prediction model. Good experimental results are obtained by pulse waveform predicting,pulse shaping and repeated iteration of laser emission data, and used in the physical experiments. A preliminary waveform control method of high power laser pulse shaping is gained. (authors)

[en] The target positioning precision of multi-beam laser facility is crucial to future inertial confinement fusion experiments, so the calculation methods have been developed for estimating the target positioning precision. The measurement method of target positioning precision based on the X-ray pinhole camera was presented. The coordinates of target center position determined by microscope and read by X-ray pinhole camera after the shoot on CH target of multi-hole, the conversion relationship of coordinates between target plane and X-ray pinhole camera was established. The template of focal area was acquired after the shoot of focal area target. The match method of template was adopted, and the position coordinates of focal area center were obtained by X-ray pinhole camera. The position of focal area center in the target plane coordinates can be calculated through the conversion of coordinates, and then the target positioning precision measurement of the laser system can be calculated. The measurement technology and methods of target positioning precision of multi-beam laser facility are presented, and the uncertainty is analyzed, consequently. (authors)

[en] Quasi regenerative amplifier is put forward, which is based on the improvement upon the regenerative amplifier. In the amplifying system, the large-aperture amplifiers are used and the beam is imaged in the amplifier to keep the shape of the beam in the course of amplifying. Experiments on the feasibility of this amplifying concept show that this kind of amplifying system even based on low-gain amplifiers can achieve high system gain and can output high-energy pulses. (authors)

[en] Based on the analytical solution of the dependence of phase matching angle on the crystal temperature, we illustrate the thermo-optic physical mechanism of temperature influence on the frequency conversion. The thermal sensitivity of the doubler and tripler crystals are numerically simulated respectively. Due to such sensitivity discrepancy among various crystals, the phase matching angle curve regarding the crystal temperature variation in our laser facility is obtained in experiment. The influence of PM angular detune on frequency conversion is theoretically analyzed under different input intensities, which is demonstrated by the conversion efficiency decline induced by temperature variation. According to the thermal sensitivity parameter obtained in experiments, we compensate the conversion efficiency with the crystal angle following, resulting in stable output of third harmonic energy. (authors)

[en] Based on the optical configuration of laser facility prototype, a precise energy control program of preamplifier system using half-plate and polarizer was fixed. The flow of the program was designed and applied to the system successfully. The program's reliability was tested by experiments. The results show that the static energy and the shot energy can be precisely controlled with the program, the static energy deviation can be reduced to 3% in 30 s, the shot energy deviation can be reduced to 5% in 12 shots and it can be also stable in a long time. (authors)

[en] A Ring-LD-pumped Nd: YLF laser amplifier system is theoretically and experimentally discussed. A structure of off-axes double passes amplifier is used. The results of experiment shown that 109 mJ output energy with a net gain of 1115 is obtained under 150 μJ input energy; a compact side-pumped structure is used to obtain a high transferring efficiency of LD array, 1.01 J output energy is achieved at 1053 nm. (authors)

[en] Using a self-made software named CatchGhost the ghost points' position and energy in a coaxial optic systems were calculated accurately in a short time without omission. The software can carry out massive calculation in a short time, and pick out the harmful ghosts in system automatically. Because all the elements which are related to beams' energy,including the pinhole' effect, reflectivity,gain and loss,are counted, data of ghost points given by the software are exact and useful. (authors)

[en] Mission-availability of inertial confinement fusion (ICF) laser facilities is considered as an important factor of facility construction. Based on basic models for mission-availability, processes of the facility performing tasks are analyzed with their types and a model diagram of mission-time for indicating time-limits of a mission and its repair presented, and then a mission-availability evaluation model for a single mission is given. Utilizing curve-fitting and goodness-of-fit test methods, and considering different impact on next missions and its probability, a mission-availability evaluation model for multiple tasks of the facilities is constructed. And then, the facility mission-availability evaluation methods and its steps are definitely given to provide a general model and method for systematic research of ICF laser facility mission-availability evaluation. Failure data of SG-Ⅲ prototype facility during operation are processed and analyzed by the use of the evaluation approach, to verify that the approach and the model are correct and economical. The results will be directly used for reliability engineering construction of SG-Ⅲ laser facility. (authors)

[en] To account for output power balancing capability of large laser facilities, a synthetic method with beam to beam root-mean-square is presented. Firstly, a conversion process for the facilities from original data of beam powers to regular data is given. The regular data contribute to the normal distribution approximately, and then a corresponding simple method of root-mean-square for beam to beam power balancing capability is given.Secondly, based on theory of total control charts and cause-selecting control charts, control charts with root-mean-square are established which show short-term variety of power balancing capability of the facilities. Mean rate of failure occurrence is also defined and used to describe long-term trend of global balancing capabilities of the facilities. Finally, advantages of the intuitive and efficient diagnosis for synthetic methods are illustrated by analysis of experimental data. (authors)