Laser-Induced Plasma Micromachining Process: Principles and Performance

2015 ◽  
Vol 3 (3) ◽  
Author(s):  
Kumar Pallav ◽  
Ishan Saxena ◽  
K. F. Ehmann
Keyword(s):  
Material Removal ◽  
Dielectric Breakdown ◽  
Dielectric Material ◽  
Experimental Conditions ◽  
Plasma Generation ◽  
Laser Induced Plasma ◽  
Wide Range ◽  
Matter Interaction ◽  
And Performance ◽  
Ultrashort Laser

Laser-induced plasma micromachining (LIP-MM) is a novel multimaterial and tool-less micromachining process. It utilizes tightly focused ultrashort laser irradiation to generate plasma through laser-induced dielectric breakdown in a dielectric material. The plasma facilitates material removal through plasma–matter interaction spot through vaporization and ablation. The paper introduces the LIP-MM process, discusses the underlying principles behind plasma generation and machining, and proves its feasibility by describing the experimental conditions under which plasma generation and machining occur. Upon successful commercial realization of this novel process, the key benefits envisaged are micromachining with better accuracy and better surface integrity, minimal subsurface damage, relatively smaller heat-affected zone (HAZ) and low roughness in a wide range of materials including those that are difficult to machine by some of the most successful micromachining processes such as micro-electrodischarge machining (EDM) and laser ablation.

Line-Based Laser Induced Plasma Micro-Machining (L-LIPMM)

2013 ◽  
Author(s):  
Rajiv Malhotra ◽  
Ishan Saxena ◽  
Kornel Ehmann ◽  
Jian Cao
Keyword(s):  
Laser Ablation ◽  
Process Parameters ◽  
Ultrashort Pulse ◽  
Experimental Setup ◽  
Micro Machining ◽  
Ultrashort Pulse Laser ◽  
Plasma Generation ◽  
Laser Induced Plasma ◽  
Laser Micro Machining ◽  
Wide Range

Recently, the technique of Spot-based Laser Induced Plasma Micro-Machining (Spot-LIPMM) has been developed to address the limitations of conventional ultrashort pulse laser micro-machining. Its main advantages are adaptability to a wide range of materials and superior wall geometries. We propose a variation of the Spot-LIPMM process by creating line plasma instead of spot plasma, with the use of suitable optics. This paper describes the experimental setup used to create line plasma and the process used for micro-machining with L-LIPMM. Optics simulations are developed as a means of guiding the choice of optics to be used for line plasma generation and estimating the energy and shape of the plasma created. It is shown that this Line-based LIPMM (L-LIPMM) process is capable of micromachining channels at a much higher speed than conventional Spot-based laser ablation or spot-based LIPMM. Additionally, the effects of process parameters on machined geometry using L-LIPMM are discussed.

Simulation of Ultrashort Laser Pulse Absorption At the Water-metal Interface in Laser-Induced Plasma Micro-Machining

2020 ◽  
Author(s):  
Jiaxi Xie ◽  
Kornel Ehmann ◽  
Jian Cao
Keyword(s):  
Dielectric Breakdown ◽  
Constitutive Relations ◽  
Three Dimensional ◽  
Optical Breakdown ◽  
Micro Machining ◽  
Metal Interface ◽  
Breakdown Threshold ◽  
Laser Induced Plasma ◽  
Water Metal ◽  
Ultrashort Laser

Abstract This work proposes a physically consistent numerical model to simulate ultrashort laser absorption by a metallic workpiece at the water-metal interface when optical breakdown of the dielectric occurs. The simulation couples the framework of the Finite-Difference Time-Domain method used in computational electromagnetics with the constitutive relation derived from both the model of direct ablation of metals and the first order model of water breakdown. The simulation is used to describe interface ablation processes such as Laser-Induced Plasma Micro-Machining. Applied to the water-aluminum interface, the model is able to describe the metal absorption and the dielectric breakdown threshold in three-dimensional geometry. It is an extensible monolithic approach in which the absorption by different materials can be described by simply changing the constitutive relations.

scholarly journals The Optical and Electrical Performance of CuO Synthesized by Anodic Oxidation Based on Copper Foam

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5411
Author(s):  
Boyou Wang ◽  
Binhua Cao ◽  
Chen Wang ◽  
Yubo Zhang ◽  
Huifang Yao ◽  
...  
Keyword(s):  
Anodic Oxidation ◽  
Current Density ◽  
Oxide Semiconductor ◽  
Electrical Performance ◽  
Experimental Conditions ◽  
Electrochemical Tests ◽  
Copper Foam ◽  
Wide Range ◽  
And Performance ◽  
Cuo Nanosheets

Metal oxide semiconductor materials have a wide range of applications in the field of solar energy conversion. In this paper, CuO was prepared directly on copper foam substrate by anodic oxidation. The effects of current density and anodizing temperature on sample preparation and performance were studied. Field emission scanning electron microscopy (FESEM) and X-ray diffractometer (XRD) had been used to determine the morphology and phase structure of the sample, and its optical and electrical properties were discussed through UV-vis spectrophotometer and electrochemical tests. In addition, the influences of experimental conditions such as current density and reaction temperature on the morphology and properties of CuO were systematically discussed. The FESEM images showed that as the anodic oxidation temperature increase, the morphology of the prepared sample changed from nanowires to leaf-like CuO nanosheets. According to the results of XRD, the structure of prepared CuO was monoclinic, and the intensity of diffraction peaks gradually increased as anodizing temperature increased. We found that the optimum current density and anodizing temperature were 20 mA cm−2 and 60 °C, respectively. The results of electrochemical indicated that the CuO electrode based on copper foam (CuO/Cu foam) prepared at the optimum exhibited the highest specific capacitance (0.1039 F cm−2) when the scan rate was 2 mV s−1.

Comparative Assessment of the Laser-Induced Plasma Micromachining and the Ultrashort Pulsed Laser Ablation Processes

2014 ◽  
Vol 2 (3) ◽  
Author(s):  
Kumar Pallav ◽  
Ishan Saxena ◽  
Kornel F. Ehmann
Keyword(s):  
Laser Ablation ◽  
Material Removal ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Comparative Assessment ◽  
Ablation Process ◽  
Laser Induced Plasma ◽  
Laser Ablation Process ◽  
Matter Interaction ◽  
Ultrashort Pulsed Laser

The ultrashort pulsed laser ablation process is a well-established micromachining process and has been at the center of manufacturing research in the past decade. However, it has its own limitations, primarily due to the involvement of various material-specific laser and machining process parameters. The laser-induced plasma micromachining (LIP-MM) is a novel tool-less and multimaterial selective material removal type of micromachining process. In a manner similar to ultrashort pulsed laser ablation, it also removes material through an ultrashort pulsed laser beam. However, instead of direct laser–matter interaction, it uses the laser beam to generate plasma within a transparent dielectric media that facilitates material removal through plasma–matter interaction and thus circumvents some of the limitations associated with the ultrashort pulsed laser ablation process. This paper presents an experimental investigation on the comparative assessment of the capabilities of the two processes in the machining of microchannels in stainless steel. For this purpose, microchannels were machined by the two processes at similar pulse energy levels and feed-rate values. The comparative assessment was based on the geometric characteristics, material removal rate (MRR), heat-affected zone and shock-affected zone (HAZ, SAZ), and the range of machinable materials.

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

2019 ◽  
Author(s):  
Christopher John ◽  
Greg M. Swain ◽  
Robert P. Hausinger ◽  
Denis A. Proshlyakov
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Heme Iron ◽  
Chemical Transformations ◽  
Experimental Conditions ◽  
Strongly Coupled ◽  
Non Heme Iron ◽  
Reversible Redox ◽  
Wide Range ◽  
Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

STEREOTYPE THREAT AND STEREOTYPE LIFT: THE CASE OF 10 YEAR OLD GIRLS AND BOYS

2016 ◽  
Vol 12 (4) ◽  
pp. 21-32
Author(s):  
Anna Kwiatkowska ◽  
Małgorzata Mróz
Keyword(s):  
Stereotype Threat ◽  
Cognitive Performance ◽  
Significant Interaction ◽  
Self Esteem ◽  
The Self ◽  
Experimental Conditions ◽  
Significant Interaction Effect ◽  
Significant Drop ◽  
Stereotype Lift ◽  
And Performance

The aim of this study was to examine the effects of stereotypical and counter-stereotypicalinformation on the self-esteem and cognitive performance of 10-year-old children. Our sampleconsisted of 37 girls and 37 boys. Children were presented with 10 “mathematical” puzzles in threeexperimental conditions: stereotypical (boys are better), counter-stereotypical (girls are better), andthe control condition (no particular information). Self-esteem was measured using a non-verbaltask. The results showed a significant interaction effect of “condition x sex” on self-esteem andperformance. Girls revealed no significant differences between control and experimental conditions,while boys showed a significant drop in self-esteem and performance in the counter-stereotypicalcondition as compared to the control condition and a significant lift in self-esteem and performancein the stereotypical condition as compared to the control condition.

Analysis of organic removal rates in the aerated submerged fixed film process

1998 ◽  
Vol 38 (8-9) ◽  
pp. 213-221 ◽  
Author(s):  
Mohamed F. Hamoda ◽  
Ibrahim A. Al-Ghusain
Keyword(s):  
Pilot Plant ◽  
Removal Rate ◽  
Domestic Wastewater ◽  
Removal Rates ◽  
Hydraulic Loading ◽  
Organic Removal ◽  
Wide Range ◽  
Fixed Film ◽  
Cod Removal Rate ◽  
And Performance

Performance data from a pilot-plant employing the four-stage aerated submerged fixed film (ASFF) process treating domestic wastewater were analyzed to examine the organic removal rates. The process has shown high BOD removal efficiencies (&gt; 90%) over a wide range of hydraulic loading rates (0.04 to 0.68 m3/m2·d). It could also cope with high hydraulic and organic loadings with minimal loss in efficiency due to the large amount of immobilized biomass attained. The organic (BOD and COD) removal rate was influenced by the hydraulic loadings applied, but organic removal rates of up to 104 kg BOD/ m2·d were obtained at a hydraulic loading rate of 0.68 m3/m2·d. A Semi-empirical model for the bio-oxidation of organics in the ASFF process has been formulated and rate constants were calculated based on statistical analysis of pilot-plant data. The relationships obtained are very useful for analyzing the design and performance of the ASFF process and a variety of attached growth processes.

scholarly journals Low-Energy Electron Damage to Condensed-Phase DNA and Its Constituents

2021 ◽  
Vol 22 (15) ◽  
pp. 7879
Author(s):  
Yingxia Gao ◽  
Yi Zheng ◽  
Léon Sanche
Keyword(s):  
Condensed Phase ◽  
Genetic Material ◽  
High Energy ◽  
Dna Lesions ◽  
Low Energy ◽  
Experimental Investigations ◽  
Experimental Conditions ◽  
Strand Breaks ◽  
Sequence Of Events ◽  
Wide Range

The complex physical and chemical reactions between the large number of low-energy (0–30 eV) electrons (LEEs) released by high energy radiation interacting with genetic material can lead to the formation of various DNA lesions such as crosslinks, single strand breaks, base modifications, and cleavage, as well as double strand breaks and other cluster damages. When crosslinks and cluster damages cannot be repaired by the cell, they can cause genetic loss of information, mutations, apoptosis, and promote genomic instability. Through the efforts of many research groups in the past two decades, the study of the interaction between LEEs and DNA under different experimental conditions has unveiled some of the main mechanisms responsible for these damages. In the present review, we focus on experimental investigations in the condensed phase that range from fundamental DNA constituents to oligonucleotides, synthetic duplex DNA, and bacterial (i.e., plasmid) DNA. These targets were irradiated either with LEEs from a monoenergetic-electron or photoelectron source, as sub-monolayer, monolayer, or multilayer films and within clusters or water solutions. Each type of experiment is briefly described, and the observed DNA damages are reported, along with the proposed mechanisms. Defining the role of LEEs within the sequence of events leading to radiobiological lesions contributes to our understanding of the action of radiation on living organisms, over a wide range of initial radiation energies. Applications of the interaction of LEEs with DNA to radiotherapy are briefly summarized.

scholarly journals Review of the Upright Balance Assessment Based on the Force Plate

2021 ◽  
Vol 18 (5) ◽  
pp. 2696
Author(s):  
Baoliang Chen ◽  
Peng Liu ◽  
Feiyun Xiao ◽  
Zhengshi Liu ◽  
Yong Wang
Keyword(s):  
Postural Balance ◽  
Force Plate ◽  
Assessment Method ◽  
Balance Assessment ◽  
Experimental Conditions ◽  
Methodological Research ◽  
Assessment Tests ◽  
Wide Range ◽  
Foot Posture ◽  
Plate System

Quantitative assessment is crucial for the evaluation of human postural balance. The force plate system is the key quantitative balance assessment method. The purpose of this study is to review the important concepts in balance assessment and analyze the experimental conditions, parameter variables, and application scope based on force plate technology. As there is a wide range of balance assessment tests and a variety of commercial force plate systems to choose from, there is room for further improvement of the test details and evaluation variables of the balance assessment. The recommendations presented in this article are the foundation and key part of the postural balance assessment; these recommendations focus on the type of force plate, the subject’s foot posture, and the choice of assessment variables, which further enriches the content of posturography. In order to promote a more reasonable balance assessment method based on force plates, further methodological research and a stronger consensus are still needed.

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