# Numerical model of the plasma formation at electron beam welding

## Abstract

The model of plasma formation in the keyhole in liquid metal as well as above the electron beam welding zone is described. The model is based on solution of two equations for the density of electrons and the mean electron energy. The mass transfer of heavy plasma particles (neutral atoms, excited atoms, and ions) is taken into account in the analysis by the diffusion equation for a multicomponent mixture. The electrostatic field is calculated using the Poisson equation. Thermionic electron emission is calculated for the keyhole wall. The ionization intensity of the vapors due to beam electrons and high-energy secondary and backscattered electrons is calibrated using the plasma parameters when there is no polarized collector electrode above the welding zone. The calculated data are in good agreement with experimental data. Results for the plasma parameters for excitation of a non-independent discharge are given. It is shown that there is a need to take into account the effect of a strong electric field near the keyhole walls on electron emission (the Schottky effect) in the calculation of the current for a non-independent discharge (hot cathode gas discharge). The calculated electron drift velocities are much bigger than the velocity at which currentmore »

- Authors:

- The Department for Applied Physics, Perm National Research Polytechnic University, Perm 614990 (Russian Federation)
- (Russian Federation)
- Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Shose, 1784 Sofia (Bulgaria)
- (Bulgaria)

- Publication Date:

- OSTI Identifier:
- 22399196

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 1; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ATOMS; CATHODES; DIFFUSION EQUATIONS; ELECTRIC CURRENTS; ELECTRIC FIELDS; ELECTRON BEAM WELDING; ELECTRON DRIFT; ELECTRON EMISSION; ELECTRONS; EXCITATION; IONS; LIQUID METALS; MASS TRANSFER; MATHEMATICAL SOLUTIONS; PLASMA; PLASMA INSTABILITY; POISSON EQUATION; SCHOTTKY EFFECT; VAPORS

### Citation Formats

```
Trushnikov, D. N., E-mail: trdimitr@yandex.ru, The Department for Welding Production and Technology of Constructional Materials, Perm National Research Polytechnic University, Perm 614990, Mladenov, G. M., E-mail: gmmladenov@abv.bg, and Technology Centre of Electron Beam and Plasma Technologies and Techniques, 68-70 Vrania, ap.10, Banishora, 1309 Sofia.
```*Numerical model of the plasma formation at electron beam welding*. United States: N. p., 2015.
Web. doi:10.1063/1.4905193.

```
Trushnikov, D. N., E-mail: trdimitr@yandex.ru, The Department for Welding Production and Technology of Constructional Materials, Perm National Research Polytechnic University, Perm 614990, Mladenov, G. M., E-mail: gmmladenov@abv.bg, & Technology Centre of Electron Beam and Plasma Technologies and Techniques, 68-70 Vrania, ap.10, Banishora, 1309 Sofia.
```*Numerical model of the plasma formation at electron beam welding*. United States. doi:10.1063/1.4905193.

```
Trushnikov, D. N., E-mail: trdimitr@yandex.ru, The Department for Welding Production and Technology of Constructional Materials, Perm National Research Polytechnic University, Perm 614990, Mladenov, G. M., E-mail: gmmladenov@abv.bg, and Technology Centre of Electron Beam and Plasma Technologies and Techniques, 68-70 Vrania, ap.10, Banishora, 1309 Sofia. Wed .
"Numerical model of the plasma formation at electron beam welding". United States.
doi:10.1063/1.4905193.
```

```
@article{osti_22399196,
```

title = {Numerical model of the plasma formation at electron beam welding},

author = {Trushnikov, D. N., E-mail: trdimitr@yandex.ru and The Department for Welding Production and Technology of Constructional Materials, Perm National Research Polytechnic University, Perm 614990 and Mladenov, G. M., E-mail: gmmladenov@abv.bg and Technology Centre of Electron Beam and Plasma Technologies and Techniques, 68-70 Vrania, ap.10, Banishora, 1309 Sofia},

abstractNote = {The model of plasma formation in the keyhole in liquid metal as well as above the electron beam welding zone is described. The model is based on solution of two equations for the density of electrons and the mean electron energy. The mass transfer of heavy plasma particles (neutral atoms, excited atoms, and ions) is taken into account in the analysis by the diffusion equation for a multicomponent mixture. The electrostatic field is calculated using the Poisson equation. Thermionic electron emission is calculated for the keyhole wall. The ionization intensity of the vapors due to beam electrons and high-energy secondary and backscattered electrons is calibrated using the plasma parameters when there is no polarized collector electrode above the welding zone. The calculated data are in good agreement with experimental data. Results for the plasma parameters for excitation of a non-independent discharge are given. It is shown that there is a need to take into account the effect of a strong electric field near the keyhole walls on electron emission (the Schottky effect) in the calculation of the current for a non-independent discharge (hot cathode gas discharge). The calculated electron drift velocities are much bigger than the velocity at which current instabilities arise. This confirms the hypothesis for ion-acoustic instabilities, observed experimentally in previous research.},

doi = {10.1063/1.4905193},

journal = {Journal of Applied Physics},

number = 1,

volume = 117,

place = {United States},

year = {Wed Jan 07 00:00:00 EST 2015},

month = {Wed Jan 07 00:00:00 EST 2015}

}