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A 700-kA gas switch with graphite electrodes for pulsed power supply module has been developed. This paper describes the design, construction, and testing of the high-current gas switch and its trigger system. The two-electrode gas switch is selected, which suffers high peak and fast rise time currents. The trigger generator based on resonant charging of a pulse transformer is constructed to trigger the gas spark. An electrodynamic force model of switch electrodes is established. The electrodynamic force of connecting wires is also calculated. By comparison of the mechanical strengths of polyformaldehyde, epoxy, and fiber-reinforced plastic (FRP) rods, where FRP rods are selected as switch rods, the experimental results show that the mechanical strength of the switch increases by 200%. Extensive electric testing has proven the operating parameters of the switch and its trigger system. The experimental results show that the measured discharge current waveform is demonstrated to be over a 700-kA peak current and a 500- $\mu \text{s}$ pulsewidth. The transfer charge per shot is more than 500 C.

Reliability is critical for complex engineering systems. Traditionally, reliability analysis and fault diagnosis of complex engineering systems is based on reliability block diagram and fault tree. These methods are limited either on the flexibility for system characterization or on the capability for quantitative analysis. Recently, the Bayesian network has been introduced in reliability engineering, and it has been demonstrated with great flexibility. In this article, the Bayesian network is investigated for reliability analysis and fault diagnosis of complex engineering systems through two real cases. It includes the case of a high-speed train representing the complex system with standardized components and the case of a critical subsystem of a high-power solid-state laser representing the complex system with highly customized components. In particular, Bayesian networks are constructed to model the reliability of these systems, where transformations of reliability block diagram and fault tree into Bayesian networks are presented. Reliability assessment of the systems is obtained through forward inference of Bayesian network. In addition, fault diagnosis is studied for identifying critical components, major causes, and diagnosis routes by utilizing backward inference of Bayesian network.

The Integration Test Bed (ITB) is a large-aperture single-beam Nd:glass laser system, built to demonstrate the key technology and performance of the laser drivers. It uses two multipass slab amplifiers. There are four passes through the main amplifier and three passes through the booster amplifier. The output beam size is 360mm by 360mm, at the level of 1% of the top fluence. The designed output energy of ITB at 1053nm is 15kJ in a 5ns flat-in-time (FIT) pulse, the third harmonic conversion efficiency is higher than 70%. The first phase of the ITB has been completed in July 2013. A series of experiments demonstrated that laser performance meets or exceeds original design requirements. It has achieved maximum energies at 1053nm of 19.6kJ at 5ns and 21.5kJ at 10ns. Based on a pair of split third harmonic generation KDP crystals, the third harmonic conversion efficiency of about 70% and 3ω mean fluences as high as 8.4 J/cm 2 have been obtained with 5ns FIT pulse.

We present work on the design and physical performances for a large-aperture multisegment amplifier, which is an engineering prototype amplifier for our technical-integration-line facility. The amplifier consists of 4×2 apertures with each clear aperture about 300×300 mm. Each amplifier module consists of eight laser slabs, arranged four high, two wide, and one long, and twenty high-pulse power flashlamps with an input electric energy of about 23 kJ per lamp. These twenty flashlamps are arranged in a 6-8-6 scheme. The central eight flashlamps will irradiate their energy to the laser slabs in two directions to increase the pumping transfer efficiency. Experimental results indicated that the energy stored in the upper laser level is about 0.24 J/cm 3 , which corresponds to an energy storage efficiency of about 3.0%. Finally, with an 1.053-μm laser probe we obtained a small-signal gain coefficient of 5.0% cm –1 .

We have measured the Raman spectra of oxidized nicotinamide adenine dinucleotide, NAD+, and its reduced form, NADH, as well as a series of fragments and analogues of NAD+ and NADH. In addition, we have studied the effects of pH as well as deuteration of the exchangeable protons on the Raman spectra of these molecules. In comparing the positions and intensities of the peaks in the fragment and analogue spectra with those of NADH and NAD+, we find that it is useful to consider these large molecules as consisting of component parts, namely, adenine, two ribose groups, two phosphate groups, and nicotinamide, for the purpose of assigning their spectral features. The Raman bands of NADH and NAD+ are found generally to arise from molecular motions in one or another of these molecular moieties, although some peaks are not quite so easily identified in this way. This type of assignment is the first step in a detailed understanding of the Raman spectra of NAD+ and NADH. This is needed to understand the binding properties of NADH and NAD+ acting as coenzymes with the NAD-linked dehydrogenases as deduced recently by using Raman spectroscopy.

We have studied the binding nature of an aromatic aldehyde to the catalytic site of liver alcohol dehydrogenase from horse (LADH) using preresonance Raman spectroscopy. The compound p-(dimethylamino)benzaldehyde (DABA) is converted to the corresponding alcohol in the presence of nicotinamide adenine dinucleotide (NADH) and a catalytic amount of enzyme at neutral pH. A stable ternary complex of LADH/NADH/DABA can be formed if enzyme and coenzyme are in excess at high pH [Jagodzinski, P. W., Funk, G. F., & Peticolas, W. L. (1982) Biochemistry 21, 2193-2202]. We have obtained the preresonance Raman spectrum of bound DABA by subtracting the contribution of the binary complex of LADH/NADH from the spectrum of this stable ternary complex. In order to understand the normal mode patterns of DABA, four isotopically labeled DABA derivatives were synthesized and their Raman spectra, in solution and in the ternary complex, were measured. Three of these compounds contain substitutions in the functionally important aldehyde moiety: (i) In one such substitution, the aldehydic hydrogen atom was replaced by a deuterium; (ii) in another, this hydrogen atom was replaced by deuterium, and the aldehydic carbon atom was replaced by 13C; and (iii) in the third derivative, only the carbon atom was replaced by 13C. The fourth derivative has had the two hydrogen atoms at the 3- and 5-positions of the DABA ring replaced by deuterium atoms. We find that many of the spectral modes are fairly extended, involving both stretching and bending motions of the entire molecule, although a few modes are quite localized. We find that the normal mode structure of DABA changes considerably when it binds to LADH/NADH. As a model for the bound DABA, we have examined the zinc complexes of DABA (and all four isotopically labeled samples) in anhydrous diethyl ether and methylene chloride. A striking correspondence between the Raman spectra of the enzyme-bound DABA and DABA-Zn complexes in solution is found, which extends to all the isotopically labeled derivatives. This suggests that one of the major roles of LADH in the binding of DABA is to provide a divalent zinc ion to form a first-sphere Lewis acid complex. The data also suggest other interactions between enzyme-bound DABA with its protein surroundings and with the coenzyme NADH are quite minor. An estimate of the carbonyl bond character of bound DABA had been made on the basis of the response of Raman bands to isotopic labeling and on trends observed in spectra of DABA in solvents of various polarities.(ABSTRACT TRUNCATED AT 400 WORDS)

We report the Raman spectra of reduced and oxidized nicotinamide adenine dinucleotide (NADH and NAD+, respectively) and adenosine 5'-diphosphate ribose (ADPR) when bound to the coenzyme site of liver alcohol dehydrogenase (LADH). The bound NADH spectrum is calculated by taking the classical Raman difference spectrum of the binary complex, LADH/NADH, with that of LADH. We have investigated how the bound NADH spectrum is affected when the ternary complexes with inhibitors are formed with dimethyl sulfoxide (Me2SO) or isobutyramide (IBA), i.e., LADH/NADH/Me2SO or LADH/NADH/IBA. Similarly, the difference spectra of LADH/NAD+/pyrazole or LADH/ADPR with LADH are calculated. The magnitude of these difference spectra is on the order of a few percent of the protein Raman spectrum. We report and discuss the experimental configuration and control procedures we use in reliably calculating such small difference signals. These sensitive difference techniques could be applied to a large number of problems where the classical Raman spectrum of a "small" molecule, like adenine, bound to the active site of a protein is of interest. The spectrum of bound ADPR allows an assignment of the bands of the bound NADH and NAD+ spectra to normal coordinates located primarily on either the nicotinamide or the adenine moiety. By comparing the spectra of the bound coenzymes with model compound data and through the use of deuterated compounds, we confirm and characterize how the adenine moiety is involved in coenzyme binding and discuss the validity of the suggestion that the adenine ring is protonated upon binding. The nicotinamide moiety of NADH shows significant molecular changes upon binding.(ABSTRACT TRUNCATED AT 250 WORDS)