Thermodynamic approach to the quantitative interpretation of sputtered ion mass spectra

Thermodynamic and transport properties of high temperature equilibrium air plasmas have been calculated in a wide pressure (\(0.01\div100\) atm) and temperature range (\(50\div60\,000\) K). The results have been obtained by using a self-consistent approach for the thermodynamic properties and higher order approximation of the Chapman-Enskog method for the transport coefficients. Debye-Hukel corrections have been considered in the thermodynamic properties while collision integrals of charge-charge interactions have been obtained by using a screened Coulomb potential. Calculated values have been fitted by closed forms ready to be inserted in fluid dynamic codes.

Thermodynamic and transport properties in equilibrium air plasmas in a wide pressure and temperature range

Hybrid welding, using the combination of a laser and an electrical arc, is designed to overcome problems commonly encountered during either laser or arc welding such as cracking, brittle phase formation and porosity. When placed in close contact with each other, the two heat sources interact in such a way as to produce a single high intensity energy source. This synergistic interaction of the two heat sources has been shown to alleviate problems commonly encountered in each individual welding process. Hybrid welding allows increased gap tolerances, as compared to laser welding, while retaining the high weld speed and penetration necessary for the efficient welding of thicker workpieces. A number of simultaneously occurring physical processes have been identified as contributing to these unique properties obtained during hybrid welding. However, the physical understanding of these interactions is still evolving. This review critically analyses the recent advances in the fundamental understa...

Problems and issues in laser-arc hybrid welding

Chapter 5 – Electric Arcs and Arc Gas Heaters

A mathematical model was developed to predict radial and axial temperature profiles in an induction‐coupled plasma torch. The model employed temperature dependent physical properties and included radiation heat loss. Temperature fields based on the model were calculated for an atmospheric pressure argon plasma. Computed radial temperature profiles were in agreement with experimental profiles reported in the literature. The gas flow rate and flow pattern in the torch did not greatly affect the radial temperature profiles in the hottest region of the torch under ordinary operating conditions, also in agreement with experiment. A one‐dimensional analysis was developed which predicted these hot‐spot profiles accurately. The plasma model was also found to accurately predict distribution of energy losses from the plasma. Based on the equilibrium current density and temperature profiles provided by the model, the question of the existence of local thermodynamic equilibrium was re‐examined. It was concluded that equilibrium is closely approached in the high‐temperature central portion of the plasma, in agreement with previous investigators; however, nonequilibrium conditions can exist in the region of high temperature gradient at the plasma edge.

Temperature Profiles and Energy Balances for an Inductively Coupled Plasma Torch

The equilibrium chemical composition and the thermodynamic properties of argon plasmas have been calculated for five pressures (0.1, 0.5, 1.0, 2.0, and 5.0 atm) at 100 K deg increments for the temperature range 5000° to 35 000°K. The argon plasma is assumed to be a perfect gas complex consisting of six components, namely electrons, argon atoms, and the first four argon ions. The partition functions for these have been calculated using tabulated data for observed atomic energy levels and estimated energies for energy levels which are predicted although not observed. The partition functions were terminated by application of the Debye cutoff criterion and a corresponding lowering of the ionization potential was included. The calculated data are presented in graphical form and the method followed in calculating the partition functions is evaluated.

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Partition Functions and Thermodynamic Properties of Argon Plasma

The equilibrium chemical composition and thermodynamic properties of nitrogen and oxygen plasmas have been calculated for six pressures (0.01, 0.1, 0.5, 1.0, 2.0, and 5.0 atm) at 100° K increments for the temperature range 2000–35 000° K. The plasma is assumed to be a perfect gas complex consisting of seven components for nitrogen (i.e., molecules, singly ionized molecules, atoms, electrons, and the first three atomic ions) and eight components for oxygen (same as for nitrogen plus the first negative atomic ion). The internal partition functions for nitrogen molecular species were calculated by an approximate technique proposed by Mayer and Mayer using the most recent spectroscopic data available. For oxygen molecular species, the method of Stupochenko et al. was employed to determine the intermolecular potential curves, and the internal partition function was computed by direct summation over the energy states so determined. The electronic partition functions for atoms and atomic ions were computed using published data for observed electronic energy levels plus estimated energies for electronic states which are predicted but not spectroscopically observed. These electronic partition function series were terminated by application of the Debye cutoff criterion, and a corresponding lowering of the ionization potential was included. The two methods of computing the molecular internal partition function are compared and evaluated. Typical calculated data are presented in graphical and tabular form.

Partition Functions and Thermodynamic Properties of Nitrogen and Oxygen Plasmas

The radial temperature distribution within a cylindrically symmetric argon plasma column was determined by spectroscopic analysis for arc currents of 30 to 60 A. Temperatures obtained from absolute line and absolute continuum radiation were found to be in excellent agreement. An empirical expression, based on the Kramers‐Unsold theoretical model, was obtained for the radiated power, as a function of temperature. Using the measured temperature profiles, the calculated radiated power, and an analytical expression for the electrical conductivity, the thermal conductivity of argon was determined for the temperature range of 8500 to 12 000°K. The data were in good agreement with theoretically predicted results.

Experimental Determination of the Thermal Conductivity of Atmospheric Argon Plasma

: Thermodynamic properties of oxygen and nitrogen plasmas at various pressures and temperatures are presented. The thermodynamic properties are also presented of argon plasma at a pressure of 0.01 atmospheres, which constitutes an extension of the property values presented in 'Partition Functions and Thermodynamic Properties of Argon Plasmas', AEDC-TDR-63-146, August, 1963. The underlying theory is described in 'Partition Functions and Thermodynamic Properties of High Temperature Gases', AEDC-TDR-64-22. (Author)

Tables of thermodynamic properties of argon, nitrogen, and oxygen plasmas,

: A perturbation solution is obtained for a free jet of an electrically conducting fluid in the presence of a transverse magnetic field. The solution is obtained in closed form to first order in the perturbation parameter, which is the ratio of the magnetic force to the inertia force of the jet. Both laminar and turbulent jets are considered. (Author)

Ali Bulent Cambel

Papers

Partition Functions and Thermodynamic Properties of Argon Plasma

Partition Functions and Thermodynamic Properties of Nitrogen and Oxygen Plasmas

Experimental Determination of the Thermal Conductivity of Atmospheric Argon Plasma

Tables of thermodynamic properties of argon, nitrogen, and oxygen plasmas,

Laminar and Turbulent Magnetohydrodynamic Free Jet