Thermodynamic properties of nonideal plasmas with multiple ionization and Coulomb and hard-core interactions

Kahlbaum, Torsten; Förster, A.

doi:10.1017/s0263034600009149

Cited by 15 publications

(5 citation statements)

References 15 publications

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“…(ii) The ionization equilibrium assumed may be not fully justified for a plasma of the cathodic jet though the periodical variations of z obtained testify to its validity. Also from [27,28] one can conclude that the Saha model can be used up to N e ≈ 10 27 m −3 and T e ∼ 3-10 eV and gives a difference from a non-ideal plasma model of less than 30%.…”

Section: Discussionmentioning

confidence: 97%

Application of a vacuum arc model to the determination of cathodic microjet parameters

Krinberg¹,

Lukovnikova²

1996

J. Phys. D: Appl. Phys.

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It is proposed to use a great body of vacuum arc plasma parameters measured in combination with a theoretical model of a current-carrying plasma jet for the determination of cathodic microjet parameters. The most probable values of microspot diameter and microjet current thus obtained lie in the range and I = 1 - 5 A, respectively. It is also shown that the mean ion charge variations observed can be essentially explained by a periodical variation of the ionization energy set with the atomic number of the cathode material.

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Section: Discussionmentioning

confidence: 97%

Application of a vacuum arc model to the determination of cathodic microjet parameters

Krinberg¹,

Lukovnikova²

1996

J. Phys. D: Appl. Phys.

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“…For the quantitative determination of AIz we need an explicit expression for the free energy density. Following the treatment of Ebeling (1990), Kahlbaum and Forster (1990) and Forster et al (1991) we adopt the following basic strxture (18) Without going into details we note that the ideal part takes into account the partial degeneration of the electrons at higher densities. The Coulomb (Coul) contribution is constructed by means of Pade approximations to interpolate between the quantum-corrected Debye law and analytical expressions for the strongly coupled multicomponent ionic subsystem at high densities, which is screened by a degenerate electron liquid.…”

Section: Pressure Ionizationmentioning

confidence: 99%

Pressure ionization: its role in metal vapour vacuum arc plasmas and ion sources

Anders¹,

Anders²,

Förster³

et al. 1992

Plasma Sources Sci. Technol.

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In most plasmas ionization is brought about by classical ionizing collisions between panicles. In metal vapour vacuum arc plasmas and ion sources, however, pressure ionization plays an important role in determining the final ion composition. In this paper we describe the basic mechanism of pressure ionization as a collective phenomenon in non-ideal plasmas, induced mainly by the many-panicle Coulomb interaction and quantum-mechanical exchange. Then we outline the properties of the cathode spot plasmas of vacuum arc discharges. The path of the cathode material in the electron density-temperature phase diagram is considered; starting from the solid, the matter is heated, forms a liquid and then a supercritical fluid which expands explosively, driven by a very high pressure gradient. The final ion charge state distribution is produced and frozen in the transition from the dense. non-ideal plasma (where pressure ionization is dominant) to the expanded, ideal, non-equilibrium plasma. We conclude that the final ion charge state distribution depends on the thermophysical properties of the solid and liquid cathode material as well as on the electronic structure of its atoms and ions. Some consequences for the performance of the metal vapour vacuum arc ion source are discussed.

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“…assuming Boltzmann distribution of excited states and using transition probability A ul and upper level energy E u from NIST data base [9]. Here Z(T ) is the partition function which is calculated according to the Planck-Larkin relation [10,11]. g u is the statistical weight, c the speed of light in vacuum, k and h are the Boltzmann and Planck constants, respectively.…”

Section: Analysis Of Radiation Measurementsmentioning

confidence: 99%

Arc temperatures in a circuit breaker experiment from iterative analysis of emission spectra

Franke¹,

Methling²,

Uhrlandt³

et al. 2020

J. Phys. D: Appl. Phys.

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A switching-off process very similar to those in real high-voltage self-blast circuit-breakers is emulated in a model chamber to study the arc properties by optical emission spectroscopy. The arc is operated in a chamber filled with SF 6 between a pin-tulip contact system enclosed by a PTFE nozzle. Transparent windows in the chamber wall and a slit in the nozzle enable an optical investigation of the arc cross section less than one millisecond before current zero. The side-on radiance of a fluorine atom lines has been measured with an imaging spectroscopic system. Considering rotational symmetry of the arc the corresponding radial emission coefficients have been determined by Abel inversion. The radial temperature profiles are calculated from the emission coefficients including pressure measurements and the corresponding plasma composition. In contrast to previous studies, a specific iterative approach is proposed to consider the optical thickness of the plasma. A maximum optical thickness between 0.2 and 0.4 has been observed. Temperature profiles corrected for absorption effects show increasing maximum temperature in the arc axis with decreasing current towards current zero. The effect of the plasma composition on absolute arc temperatures is discussed. The temperature profiles can be used to validate CFD simulations of the switching-off process in the model chamber.

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Thermodynamic properties of nonideal plasmas with multiple ionization and Coulomb and hard-core interactions

Cited by 15 publications

References 15 publications

Application of a vacuum arc model to the determination of cathodic microjet parameters

Application of a vacuum arc model to the determination of cathodic microjet parameters

Pressure ionization: its role in metal vapour vacuum arc plasmas and ion sources

Arc temperatures in a circuit breaker experiment from iterative analysis of emission spectra

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