Design and performance of photo-cell systems for pulsed laser power and energy measurements

1969 ◽  
Vol 1 (1) ◽  
pp. 1-8 ◽  
Author(s):  
J. G. Edwards
Keyword(s):  
Laser Power ◽  
Pulsed Laser ◽  
Cell Systems ◽  
And Performance ◽  
Power And Energy

Experimental Study on Testing Ni-Containing Stainless Steel Protective Coatings by Pulsed Laser Scratching

2010 ◽  
Vol 43 ◽  
pp. 651-656
Author(s):  
Ai Xin Feng ◽  
Yu Peng Cao ◽  
Chuan Chao Xu ◽  
Huai Yang Sun ◽  
Gui Fen Ni ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Power Density ◽  
Laser Power ◽  
Protective Coatings ◽  
Three Dimensional ◽  
Pulsed Laser ◽  
Laser Power Density ◽  
The Matrix ◽  
The Impact

In the experiment, we use pulsed laser to conduct discrete scratching on Ni-containing stainless steel protective coatings to test residual stress situation after the matrix is scratched; then to analyze the the impact of the impact stress wave on coating - substrate bonding strength according to the test results, finally to infer the laser power density range within which it occurs coating failure. The study shows that: after laser discrete scratching, the residual stress of the center of the laser-loaded point on matrix surface gradually reduces when the pulsed laser power density increases. The matrix produces a corresponding residual compressive stress under the laser power density reaches a certain value. The actual failure threshold values are 12.006 GW/cm2, 11.829GW/cm2 and 12.193GW/cm2 measured by the three-dimensional topography instrument testing the discrete scratch point of three groups of samples and verified by using a microscope

scholarly journals Temperature Calibration Measurements based on Laser-Induced Phosphorescence Technique for Combustion Applications

2015 ◽  
Vol 10 (1) ◽  
Keyword(s):  
Laser Radiation ◽  
Laser Beam ◽  
Intensity Ratio ◽  
Laser Power ◽  
Room Temperature ◽  
Pulsed Laser ◽  
Temperature Calibration ◽  
Phosphor Powder ◽  
Calibration Methods

Phosphor powder and phosphor-binder mixtures are successfully employed for temperature calibration measurements by using laser-induced phosphorescence (LIP) technique with an emphasis on higher precisions and accuracies than other non-intrusive methods. The phosphorescence intensities are used to perform these calibrations in three different strategies. The influence of laser power regular changes on particles heating and the calibration analyses is also carried out. A pulsed laser at 355 nm was used for exciting specimens of the phosphor powder as well as the phosphor-binder mixtures. The laser beam was directed onto the specimens and varied in three laser power levels (LPLs). The samples were kept in an oven with temperatures ranging from room temperature up to 1800 °C. The three strategies which are expressed in terms of non-dimensional intensity versus wavelength (NDI-W), normalised intensity (NI) and intensity ratio (IR) were used for the calibration assessments. A modified IR was compared with two different IRs. A precision of around ± (0.50-1.41)% was attained for different calibration methods. This research confirmed that these calibrations are possible using three different strategies, given high precisions and accuracies. The laser power alternations influenced the NI and do affect neither the NDI-W nor the IR curves. The laser radiation does not play any role for heating the particles of the studied powder.

scholarly journals Controlling the Wetting Properties of Superhydrophobic Titanium Surface Fabricated by UV Nanosecond-Pulsed Laser and Heat Treatment

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 766 ◽  
Author(s):  
The-Hung Dinh ◽  
Chi-Vinh Ngo ◽  
Doo-Man Chun
Keyword(s):  
Heat Treatment ◽  
Laser Power ◽  
Titanium Surface ◽  
Pulsed Laser ◽  
Line Pattern ◽  
Step Size ◽  
Grid Pattern ◽  
Pattern Design ◽  
Wetting Properties ◽  
Nanosecond Pulsed Laser

In this study, the effects of nanosecond-pulsed laser and pattern design were researched on the wettability of titanium material. Nanosecond-pulsed laser and heat treatment are used to fabricate superhydrophobic titanium surfaces. The effects of laser power (1–3 W) and step size (50–300 µm) on a microscale patterned titanium surface (line pattern and grid pattern) were investigated to explain the relation between microstructure and superhydrophobicity. The surface morphologies and wettability of the surfaces were analyzed by three-dimensional confocal microscopy and a contact angle meter. The results show that the laser power and pattern design affected the apparent contact angle (CA) and sliding angle (SA). The maximum step size, which could show superhydrophobicity with apparent CA > 150° and SA < 10°, was increased when the laser power increased from 1 to 3 W. Grid pattern showed isotropic wetting behavior, but line pattern showed both isotropic and anisotropic wetting behavior according to step size and laser power. Furthermore, when choosing the proper laser power and step size, the wetting properties of superhydrophobic surface such as lotus effect (apparent CA > 150° and SA < 10°) and petal effect (apparent CA > 150° and no SA) and isotropic/anisotropic behavior can be controlled for applications of water droplet control.

Modeling and Performance Analysis of the Rolls-Royce Fuel Cell Systems Limited: 1 MW Plant

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Francesco Trasino ◽  
Michele Bozzolo ◽  
Loredana Magistri ◽  
Aristide F. Massardo
Keyword(s):  
Fuel Cell ◽  
Characteristic Point ◽  
Pressure Vessels ◽  
Performance Model ◽  
System Behavior ◽  
Cell Systems ◽  
And Performance ◽  
Definition Of ◽  
Component Models ◽  
Safe Operating

This paper is focused on the performance of the 1 MW plant designed and developed by Rolls-Royce Fuel Cell Systems Limited. The system consists of a two stage turbogenerator coupled with pressure vessels containing the fuel cell stack, internal reformer, cathode ejector, anode ejector, and off-gas burner. While the overall scheme is relatively simple, due to the limited number of components, the interaction between the components is complex and the system behavior is determined by many parameters. In particular, two important subsystems such as the cathode and the anode recycle loops must be carefully analyzed also considering their interaction with and influence on the turbogenerator performance. The system performance model represents the whole, and each physical component is modeled in detail as a subsystem. The component models have been validated or are under verification. The model provides all the operating parameters in each characteristic point of the plant and a complete distribution of thermodynamics and chemical parameters inside the solid oxide fuel cell (SOFC) stack and reformer. In order to characterize the system behavior, its operating envelope has been calculated taking into account the effect of ambient temperature and pressure, as described in the paper. Given the complexity of the system, various constraints have to be considered in order to obtain a safe operating condition not only for the system as a whole but also for each of its parts. In particular each point calculated has to comply with several constraints such as stack temperature distribution, maximum and minimum temperatures, and high and low pressure spool maximum rotational speeds. The model developed and the results presented in the paper provide important information for the definition of an appropriate control strategy and a first step in the development of a robust and optimized control system.

Preparation and Microstructure Control of Protein Thin Films Deposited by Pulsed Laser Deposition and Via Colloid Chemical Routes

2003 ◽  
Vol 788 ◽  
Author(s):  
Sayuri Nakayama ◽  
Ichiro Taketani ◽  
Sanshiro Nagare ◽  
Mamoru Senna
Keyword(s):  
Thin Film ◽  
Secondary Structure ◽  
Pulsed Laser Deposition ◽  
Power Density ◽  
Laser Power ◽  
Pulsed Laser ◽  
Laser Power Density ◽  
Laser Deposition ◽  
Random Coil ◽  
Β Sheet

ABSTRACTProtein thin film (mainly silk fibroin) was prepared by pulsed laser deposition (PLD) with 1064nm IR-beam and via colloid chemical routes. Thickness, surface roughness, and microstructures of the deposited film were examined by quartz crystal microbalance sensor, field emission scanning electron microscope (FE-SEM), and atomic force microscope (AFM). The laser power density was varied systematically for PLD to control the microstructures of the film and the secondary structure (β-sheet, α-helix, or random coil) of the protein. Secondary structure of the target and film was examined by FT-IR. Films prepared by PLD comprise by agglomerated particles with their primary particle size around 30nm. The size of the primary particles was uniform, especially for the film prepared at low laser power density. At low laser power density, proportion of β-sheet increased and that of random coil decreased. Proportion of random coil was also increased by the wet colloidal process. PLD with low power density is most suitable to preserve the secondary structure in the protein thin film.

Machining and Characterization of Deep Micro Holes on Super Alloy Processed by Millisecond Pulsed Laser

2016 ◽  
Vol 703 ◽  
pp. 34-38 ◽  
Author(s):  
Yun Long Wang ◽  
Lin Zhong Zhu ◽  
Cai Yan Chen ◽  
Zhi Chen Liu ◽  
Wei Xin Ren ◽  
...  
Keyword(s):  
Laser Power ◽  
Laser Scanning ◽  
Pulsed Laser ◽  
Processing System ◽  
Longitudinal Section ◽  
Recast Layer ◽  
Numerical Control ◽  
Micro Cracks ◽  
Micro Holes ◽  
Super Alloy

In this study, a series of deep micro holes were machined on thick GH4169 super alloy by the trepan drilling, using a millisecond pulsed laser which equipped to the numerical control processing system. The microstructure of the holes including surface and longitudinal morphologies, diameter, taper, circularity, micro cracks and recast layer were systematically characterized. The surface morphology and the longitudinal section of the drilled holes were observed by Scanning Electron Microscope and 3D Laser Scanning Confocal Microscope. The method of Minimum circumcircle method was employed to evaluate the entrance and exit end circularity. The results showed that the melt and spattering accumulating around the holes decreased with the augment of laser power. The diameter of the entrance showed an increasing tendency with the growing of laser power, but the exit end was not seriously affected by the power. The micro cracks and recast layer could be found obviously, the micro cracks appeared in those zones which thermal stress concentrated, the thickness of recast layer is about 20μm and the taper and circularity were optimized at a laser power of 80-100W.

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