Coherent beam combination of a 1.08 kW fiber amplifier array has been demonstrated for the first time, to our knowledge. In experiment, nine amplifiers are tiled into 3×3 array, and output power each is approximately 120 W. A single frequency dithering algorithm used compensate phase noises between elements, which runs on signal processor based field programmable gate control amplifiers. When system goes closed loop, fringe contrast far-field intensity pattern improved more than 85%,...

Taking the improved SRS threshold formula into consideration, power scaling of tandem-pumped Yb-doped silica fiber lasers and amplifiers is analyzed by new models. The results show that primarily limited optical damage, thermal lens, while pump brightness induced limitation almost removed. It also found amplifiers, based upon state-of-art technology, have potential to achieve a limit 70.7 kW with core diameter 63.4 μm, in case strict single-mode fiber, about 13.3 numerical aperture 0.03.

Laser-induced breakdown spectroscopy (LIBS) was used in this study to measure quantitatively the sodium (Na) and potassium (K) release from burning coal particles under oxy-fuel combustion environments. A specially designed laminar premixed burner employed provide a postflame environment with different O2 CO2 concentrations, which effects of on Na K during were studied systematically. For devolatilization stage, neither nor had significant influence release. The char however, changed...

Translational, rotational, vibrational and electron temperatures of a gliding arc discharge in atmospheric pressure air were experimentally investigated using situ, non-intrusive optical diagnostic techniques. The was driven by 35 kHz alternating current (AC) power source operated glow-type regime. two-dimensional distribution the translational temperature (Tt) determined planar laser-induced Rayleigh scattering. rotational obtained simulating experimental spectra. OH A-X (0, 0) band used to...

We demonstrate a plasma discharge which is generated between two diverging electrodes and extended into gliding arc in non-equilibrium condition by an air flow at atmospheric pressure. Effects of the rates on dynamics, ground-state OH distributions spectral characterization UV emission were investigated optical methods. High-speed photography was utilized to reveal flow-rate dependent dynamics such as ignitions, propagation, short-cutting events, extinctions conversions from glowtype...

Dynamic processes in a gliding arc plasma generated between two diverging electrodes ambient air driven by 31.25 kHz AC voltage were investigated using spatially and temporally resolved optical techniques. The life cycles of the tracked fast movies high-speed camera with framing rates tens to hundreds kHz, showing details ignition, motion, pulsation, short-cutting, extinction column. ignition new discharge occurs before previous discharge. developed, moving column often short-cuts its...

Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding was generated large volume atmospheric pressure air, driven by an alternating current (AC) power source. The plasma column extended beyond the water-cooled stainless steel electrodes and stabilized matching flow speed of turbulent air jet with rated output power. Comprehensive investigations were...

Gaining information of species, temperature, and velocity distributions in turbulent combustion high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use optical spectroscopic techniques, particular laser-based diagnostics, has shown outstanding abilities performing non-intrusive situ diagnostics. development instrumentation, such as robust lasers with high pulse energy, ultra-short duration, repetition rate...

A gliding arc discharge was generated in a turbulent air flow at atmospheric pressure driven by 35 kHz alternating current (AC) electric power. The spatiotemporally resolved characteristics of the discharge, including glow-type discharges, spark-type short-cutting events and transitions among different types were investigated using simultaneously optical electrical diagnostics. shows sinusoidal-like voltage waveforms with peak hundreds milliamperes. frequency emission intensity variation is...

A non-thermal gliding arc discharge was generated at atmospheric pressure in an air flow. The dynamics of the plasma column and tracer particles were recorded using two synchronized high-speed cameras. Whereas data analysis for such systems has previously been performed 2D (analyzing single camera image), we provide here a 3D that includes reconstructions particle tracking velocimetry based on discrete tomography methods. analysis, particular, determination slip velocity between gas flow,...

A burner design with integrated electrodes was used to couple a gliding arc (GA) discharge high-power and large-scale turbulent flame for stabilization. Simultaneous OH CH2O planar laser-induced fluorescence (PLIF) CH PLIF measurements were conducted visualize instantaneous structures of the GA-assisted flame. Six different regions resolved by multi-species measurements, including plasma core, discharge-induced region, post-flame front, preheat region fresh gas mixture. Specifically, profile...

It is well known that spectroscopic measurements suffer from an interference as stray light, causing spectral distortion reduces measurement accuracy. In severe situations, light may even obscure the existence of lines. Here a novel general method presented, named Periodic Shadowing, enables effective elimination in spectroscopy and experimental results are provided to demonstrate its capabilities versatility. Besides efficiency, implementing it arrangement comes at virtually no added complexity.

A non-equilibrium quenched plasma is prepared using a gliding-arc discharge generated between diverging electrodes and extended by gas flow. It can be operated at atmospheric pressure applied to surface treatment improve adhesion properties of material surfaces. In this work, glass-fibre-reinforced polyester plates were treated an with air flow vinylester adhesive. The water-cooled so as operate the gliding arc continually. improved wettability increased density oxygen-containing polar...

Quantitative characterization of a high-power glow-mode gliding arc (GM-GA) discharge operated in open air is performed using current-voltage lumped model that built from the perspective energy balance and electron conservation. The GM-GA powered by 35 kHz alternating current power supply. Instantaneous images volume are recorded high-speed camera at frame rate 50 kHz, synchronized with simultaneously voltage waveforms. Detailed analyzation indicates electrical input dissipated mainly...

A high-power gliding arc (GA) discharge was generated in a turbulent air flow driven by 35 kHz alternating current electric power supply. The effects of the rate on characteristics GA were investigated using combined optical and electrical diagnostics. Phenomenologically, exhibits two types discharge, i.e., glow type spark type, depending rates input powers. glow-type which has peak currents hundreds milliamperes, is sustained at low rates. spark-type characterized sharp spike several...

The stability and re-ignition characteristics of the plasma column an alternating current (AC) powered gliding arc discharge operating in atmospheric-pressure air were investigated for better plasma-mode controlling optimized applications. By modulating AC power supply flow field, states afterglow varied. When pulsating sequence, re-ignitions columns introduced their studied using simultaneous high-speed photography electrical measurements. Two types observed with different decay times (the...