Dynamics of CO2 laser heated solenoids

1982 ◽  
Vol 60 (9) ◽  
pp. 1247-1256 ◽  
Author(s):  
D. C. D. McKen ◽  
W. Tighe ◽  
R. Fedosejevs ◽  
A. A. Offenberger
Keyword(s):  
Laser Energy ◽  
Plasma Temperature ◽  
Wave Model ◽  
Hydrogen Gas ◽  
Pressure Balance ◽  
Scaling Models ◽  
Simple Scaling ◽  
Gas Breakdown ◽  
Long Pulse ◽  
Laser Heated

Experimental results are reported for long pulse CO2 laser production and heating of magnetically confined plasma columns. The plasma column is produced by an ionizing and heating wave propagation along the axis of a linear magnetic solenoid when laser radiation is focused into hydrogen gas contained inside the solenoid. The axial behavior is found to be reasonably well described by a "bleaching" wave model which predicts column length as a function of time. Radial behavior, following a transient ionization and expansion phase, is determined by a balance of ion thermal conduction and inverse bremsstrahlung laser heating. A finite ionization time is observed at the gas breakdown front. Energy balance measurements indicate that most of the incident laser energy is effectively coupled to ionization and heating of the plasma. Temperature measurements show good agreement with predictions of simple scaling models from which pressure balance gives a density value in agreement with experiment.

scholarly journals Spheroidization of Nickel Powder and Coating with Carbon Layer through Laser Heating

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1641 ◽  
Author(s):  
Shuang Li ◽  
Yu-Ling Shao ◽  
Lan Cui ◽  
Sergei Kulinich ◽  
Xi-Wen Du
Keyword(s):  
Laser Heating ◽  
Nickel Powder ◽  
Carbon Layer ◽  
Liquid Droplets ◽  
Pure Ethanol ◽  
Precipitation Mechanism ◽  
Excess Carbon ◽  
Lower Solubility ◽  
Long Pulse ◽  
Laser Heated

We developed a simple and efficient process, laser heating of nickel powder in ethanol, to produce carbon-encapsulated nickel microspheres. Long-pulse-width laser heated nickel powder suspended in pure ethanol into liquid droplets. In turn, the latter droplets became sphere-like, pyrolyzed surrounding ethanol and dissolved the produced carbon atoms. Because of their lower solubility in solid nickel, excess carbon atoms were then expelled from the metal core after solidification, thus forming graphite-like shells on the laser-modified Ni spheres. Hence, after pyrolysis the transformation of carbon was found to follow the dissolution-precipitation mechanism. The produced carbon-encapsulated nickel microspheres exhibited higher oxidation resistance compared with the initial nickel powder, while keeping their magnetic properties essentially unchanged.

Development of New Material Testing Apparatus in 230 MPa Hydrogen and Evaluation of Hydrogen Gas Embrittlement of Metals

2008 ◽  
Author(s):  
Seiji Fukuyama ◽  
Masaaki Imade ◽  
Takashi Iijima ◽  
Kiyoshi Yokogawa
Keyword(s):  
High Pressure ◽  
Axial Load ◽  
Room Temperature ◽  
Hydrogen Gas ◽  
Stage Ii ◽  
Stage Iii ◽  
External Loading ◽  
Materials Testing ◽  
Pressure Balance ◽  
Testing Apparatus

A new materials testing apparatus using an external loading system in 230 MPa hydrogen at room temperature was developed. The apparatus consisted of a pressure vessel with a loading device for the slow strain rate technique (SSRT). The elimination of the axial load due to high pressure acting on the pull rod was achieved by the pressure balance method. The apparatus was designed to measure the actual load on the specimen with an external load cell irrespective of the axial load caused by high pressure and friction at the sliding seals. The hydrogen gas embrittlement (HGE) of austenitic stainless steels, SUS304, SUS316, SUS316LN, SUS316L and SUS310S of the Japanese Industrial Standard (JIS), and an iron-based superalloy, SUH660 JIS, and a nickel-based superalloy, Hastelloy C22, was evaluated by conducting SSRT tests in 210 MPa hydrogen using the apparatus at room temperature. The following was observed: SUS304, moderate HGE in stage II; SUS316, moderate HGE in stage III; SUS316LN, light HGE in stage III; SUS316L, light HGE in FS; SUS310S, undetectable HGE; SUH660, light HGE in stage III; and Hastelloy C22, heavy HGE in stage II. The HGE of the materials was also discussed.

Effect of Focusing Plane on Laser Blow-off Shock Waves from Confined Aluminum and Copper Foils

2021 ◽  
Author(s):  
Nagaraju Guthikonda ◽  
Sai Shiva S ◽  
E. Manikanta ◽  
Kameswari P S L D ◽  
V. R. Ikkurthi ◽  
...  
Keyword(s):  
Laser Energy ◽  
Plasma Temperature ◽  
Laser Pulses ◽  
Ambient Air ◽  
Rear Side ◽  
Hydrodynamic Simulations ◽  
Enhanced Absorption ◽  
532 Nm ◽  
Lower Plasma Density ◽  
Good Agreement

Abstract We present results on the dynamics of laser-induced blow-off shockwave generation from the rear side of 20 µm thick aluminum and copper foil confined with a glass (BK7) substrate. These foils are irradiated by 10 ns, 532 nm laser pulses of energy 25 – 200 mJ corresponding to the intensity range 0.2 – 10 GW/cm2. The plasma temperature at the glass-foil interface is observed to play an important role in the coupling of laser energy to the foil. From our experiments and 1D hydrodynamic simulations, we confirm that moving the glass-foil interface away from the focal plane led to (a) enhanced absorption of the laser beam by the foil resulting in ~ 30 % higher blow-off shock velocities (b) significant changes in the material ejection in terms of increased blow-off mass of the foil (c) lower plasma density and temperatures. The material ejection as well as blow-off shock velocity is higher for Al compared to Cu. The simulated shock evolution in ambient air shows a reasonably good agreement with the experimental results.

Spectroscopic Study of Pulsed Laser Induced Plasma from Aluminum Surface

1998 ◽  
Vol 526 ◽  
Author(s):  
Y. F. Lu ◽  
Z. B. Tao ◽  
M. H. Hong ◽  
D.S.H. Chan ◽  
T.S. Low
Keyword(s):  
Spectroscopic Study ◽  
Laser Energy ◽  
Plasma Temperature ◽  
Optical Emission ◽  
Spectral Lines ◽  
Aluminum Surface ◽  
Spontaneous Radiation ◽  
Incident Laser ◽  
Optical Emission Spectrum ◽  
Laser Fluences

AbstractOptical emission spectrum of aluminum plasma induced by a 1064 nm Nd:YAG laser is investigated by an Optical Multichannel Analyzer (OMA). Spectroscopic study shows that more number of Al, Al+, and Al++ spectral lines can be observed with increasing the incident laser fluence. Al, Al+, Al++ spectral lines are also observed successively with high fluence. The atomic spontaneous radiation is analyzed to interpret the calibrated plasma spectrum. The laser energy threshold for the appearance of excited Al, Al+, and Al++ spectral lines are about 0.8, 1.0 and 1.5 J/cm2 respectively. Assuming LTE (Local Thermodynamic Equilibrium) conditions, the plasma density is derived to be in the range of 0.7×1017 to 2×1017 cm-3 from the profiles of Al+ (358.7 and 286.1 nm) spectral lines with different gated times and incident laser fluences. The plasma temperature is also estimated to be 4000 ~ 8000 K, from relative intensities of two different Al I spectral lines (309.2 and 396.2 nm) with different fluence.

scholarly journals A simple model for soft X-ray conversion efficiency from laser-irradiated gold disk targets

1984 ◽  
Vol 2 (3) ◽  
pp. 303-307 ◽  
Author(s):  
P. H. Y. Lee ◽  
H. G. Ahlstrom
Keyword(s):  
Heat Conduction ◽  
Simple Model ◽  
Conversion Efficiency ◽  
Laser Light ◽  
Laser Intensity ◽  
Laser Energy ◽  
High Irradiance ◽  
X Rays ◽  
X Ray ◽  
Laser Heated

Simple arguments are used to construct a model to explain the conversion efficiency of absorbed laser energy into soft X-rays from laser-irradiated targets. In this model, we postulate that the energy available for conversion is bounded at some low irradiance limit by heat conduction away from the laser heated spot, while at some high irradiance limit it is bounded by the energy lost in plasma blowoff. Consequently, at some appropriate laser intensity, where the sum energy of the conduction and blowoff losses is at a minimum, the X-ray conversion efficiency should reach a maximum. A specific example for gold disk targets irradiated by 0·53 μm laser light will be treated. Simple heuristic scalings of blowoff and conduction as functions of laser intensity are obtained.

scholarly journals Experiments with laser-irradiated cylindrical targets

1991 ◽  
Vol 9 (3) ◽  
pp. 725-747 ◽  
Author(s):  
C. Stöckl ◽  
G. D. Tsakiris
Keyword(s):  
Light Propagation ◽  
Energy Transport ◽  
Laser Light ◽  
Laser Energy ◽  
Axial Direction ◽  
Radiative Energy ◽  
Capillary Length ◽  
Inner Diameter ◽  
Laser Heated ◽  
Good Agreement

Results of novel experiments with laser-heated capillary targets are presented. In these experiments the interior of gold capillaries having a 200- or 700-μm inner diameter and a 2–12-mm length was axially irradiated by injection of the laser energy through one of the end openings. A frequency-doubled Nd:glass laser (λ = 0.53 μm) was employed, delivering 8-J energy in 3 ns. The experiments showed no significant backreflection of laser light. Depending on the capillary diameter and length, most of the laser energy is either transmitted or absorbed inside the capillary. The transmission of laser light was measured as a function of capillary length and found to be in good agreement with the predictions of a simple theoretical model. Two extreme cases could be identified. Capillaries with a 700-μm diameter show uninhibited laser light propagation due to multireflections off the inner wall. In contrast, at the entrance of capillaries with a 200-μm inner diameter a plasma plug forms that absorbs most of the laser energy. In both cases significant energy transport was observed to occur in the axial direction. A stable and strongly radiating plasma column is formed along the capillary axis by the collision of the radially imploding plasma. During the collision, part of the hydrodynamic energy of the plasma is converted into radiative energy. In a special case-a lower limit of ≊7% could be inferred for the conversion efficiency from laser light into X-ray radiation emitted from the rear opening of the capillary.

scholarly journals Investigation of compositional analysis and physical properties for Ni-Cr-Nb alloys using laser-induced breakdown spectroscopy

2021 ◽  
Vol 51 (3) ◽  
Author(s):  
Hussein Salloom ◽  
Tagreed Hamad
Keyword(s):  
Thermal Conductivity ◽  
Laser Energy ◽  
Plasma Temperature ◽  
Compositional Analysis ◽  
Spectral Lines ◽  
Laser Induced Breakdown Spectroscopy ◽  
Elemental Content ◽  
Empirical Formulas ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

In this work, laser-induced breakdown spectroscopy (LIBS) analysis is optimized for direct estimation of elemental composition, thermal conductivity and hardness for Ni-Cr-Nb alloys. These alloys were chosen with a variable elemental content of niobium and chromium. The influence of laser energy and shot numbers on measuring line intensity was investigated. Based on the ratio between two spectral lines, calibration curves were formed to estimate the element concentration and LIBS results were confirmed with related energy-dispersive X-ray spectroscopy (EDS) data. Hardness and thermal conductivity estimation using LIBS were done by measuring the ratio between two spectral lines, plasma excitation temperature and electron density for different samples. Semi-empirical formulas correlated hardness and thermal conductivity with plasma temperature were established.

DIAGNOSTICS OF LASER INDUCED GRAPHITE PLASMA UNDER VARIOUS PRESSURES OF AIR, HELIUM AND ARGON

2016 ◽  
Vol 78 (3) ◽  
Author(s):  
Zuhaib Haider ◽  
Kashif Chaudhary ◽  
Sufi Roslan ◽  
Jalil Ali ◽  
Yusof Munajat
Keyword(s):  
Electron Density ◽  
Laser Energy ◽  
Ambient Pressure ◽  
Plasma Temperature ◽  
Sample Surface ◽  
Ambient Atmosphere ◽  
Plasma Parameters ◽  
Saha Equation ◽  
Laser Induced Plasma ◽  
Spectroscopic Information

Laser induced plasma provides information about the elemental composition of sample surface and through spectroscopy vital information about plasma dynamics can be obtained. In this paper we present the diagnostics of laser induced plasma at various pressures of Air, Helium and Argon gases. Graphite sample was ablated with Q-smart 850 laser while spectra were captured  Plasma parameters have been calculated by using well known methods based on Saha and Boltzmann equations. Plasma temperature was calculated relative intensity of ionic carbon lines CII 251.21 nm and CII 426.73 nm while the electron density was determined by using spectroscopic information of CI 247.85 nm and CII 426.73 nm emission lines in Saha equation. Plasma temperature and electron density were found to be dependent upon nature and pressure of the ambient atmosphere. Higher temperatures and electron densities were obtained in the presence of Air as ambient environment that is attributed to electrical and physical properties of the Air. Keeping into consideration the plasma expansion in various environments the selection of a suitable ambient pressure can be made on the basis of spectral diagnostics of plasma for a particular laser energy to obtain desirable plasma temperature and electron density suited for certain applications.

Temperature characteristics of absorber for large-energy long pulse laser energy meter

2018 ◽  
Vol 47 (4) ◽  
pp. 406004 ◽  
Author(s):  
李 南 Li Nan ◽  
乔春红 Qiao Chunhong ◽  
范承玉 Fan Chengyu ◽  
杨高潮 Yang Gaochao
Keyword(s):  
Pulse Laser ◽  
Laser Energy ◽  
Large Energy ◽  
Temperature Characteristics ◽  
Energy Meter ◽  
Pulse Laser Energy ◽  
Long Pulse

Atmospheric Influences on Q-Switched Laser Sampling and Resulting Plumes

1971 ◽  
Vol 25 (6) ◽  
pp. 642-652 ◽  
Author(s):  
E. H. Piepmeier ◽  
D. E. Osten
Keyword(s):  
Laser Energy ◽  
Ambient Pressure ◽  
Large Fraction ◽  
Wave Model ◽  
Sample Surface ◽  
Copper Sample ◽  
Atmospheric Plasma ◽  
Limited Region ◽  
Single Spike ◽  
Shock Wave Model

When a 10–100-mJ single-spike Q-switched Nd laser pulse is focused on a copper sample, the presence of an atmosphere affects the spectra, the crater size, and the amount of sample vaporized. At 760 Torr the crater diameter (90 µ) and amount of sample vaporized (35 ng) remain relatively constant while at 1 Torr they both increase with increasing laser energy. Spatial changes in the spectra occur with changes in ambient pressure. The continuum intensity of the limited region just above the sample surface appears to be a better measure of the energy reaching the sample than does the energy of the laser beam. The experimental results appear to be caused by absorption of a large fraction of the laser energy in an atmospheric plasma. A radiation-supported shock-wave model is evaluated in detail and compared briefly with similar models as possible mechanisms for production of the atmospheric plasma. The analytical chemical implications of the experimental and theoretical results are discussed.

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