TY - JOUR

T1 - Estimation of plasma parameters in a pre-breakdown ionization wave at the glow discharge ignition in argon

AU - Dyatko, Nikolay A.

AU - Ionikh, Yury Z.

AU - Meshchanov, Aleksandr V

PY - 2021/5/21

Y1 - 2021/5/21

N2 - The results of an experimental study of a pre-breakdown (slow) ionization wave (IW) in argon-filled discharge tubes of 15 mm i.d. and 80 and 100 cm length at a pressure of 1 and 4 Torr are presented. The breakdown and the IW were initiated by a positive voltage pulse with an amplitude of 2 and 4 kV. The IW was detected by the light emitted from its front. The IW emission spectrum consisted of the argon atomic and ion lines. The Ar(763.5 nm) and Ar+(488.0 nm) lines were used to retrieve the electric field strength value in the IW front. For this, the intensity ratio of these lines was measured. The upper levels for these lines are excited by electron impact, and, due to a large difference between their excitation energies, this ratio strongly depends on the reduced electric field strength E/N (E is the electric field strength, N is the atom number density). Theoretical modeling makes it possible to find a relation between the line intensity ratio and the E/N value. In the model, the axial profile of the IW electric field is approximated by a rectangle with a width determined from the measured emission intensity waveform and the wave velocity. As a result, the E/N magnitude in the IW front was found for various positions along the tube. Emission intensity of the DC discharge was also measured, which allowed us to estimate the emitting level population and electron number density in the IW front. The density of seed electrons ahead of the wave is also evaluated and processes responsible for the appearance of these electrons are discussed.

AB - The results of an experimental study of a pre-breakdown (slow) ionization wave (IW) in argon-filled discharge tubes of 15 mm i.d. and 80 and 100 cm length at a pressure of 1 and 4 Torr are presented. The breakdown and the IW were initiated by a positive voltage pulse with an amplitude of 2 and 4 kV. The IW was detected by the light emitted from its front. The IW emission spectrum consisted of the argon atomic and ion lines. The Ar(763.5 nm) and Ar+(488.0 nm) lines were used to retrieve the electric field strength value in the IW front. For this, the intensity ratio of these lines was measured. The upper levels for these lines are excited by electron impact, and, due to a large difference between their excitation energies, this ratio strongly depends on the reduced electric field strength E/N (E is the electric field strength, N is the atom number density). Theoretical modeling makes it possible to find a relation between the line intensity ratio and the E/N value. In the model, the axial profile of the IW electric field is approximated by a rectangle with a width determined from the measured emission intensity waveform and the wave velocity. As a result, the E/N magnitude in the IW front was found for various positions along the tube. Emission intensity of the DC discharge was also measured, which allowed us to estimate the emitting level population and electron number density in the IW front. The density of seed electrons ahead of the wave is also evaluated and processes responsible for the appearance of these electrons are discussed.

KW - long discharge tube

KW - argon

KW - breakdown

KW - ionization wave

KW - emission spectrum

KW - ELECTRON-IMPACT EXCITATION

KW - CROSS-SECTIONS

KW - BARRIER DISCHARGE

KW - METASTABLE ATOMS

KW - LASER STATES

KW - BREAKDOWN

KW - TUBE

KW - COEFFICIENTS

KW - PROPAGATION

KW - POPULATION

UR - https://www.mendeley.com/catalogue/9f0b54a3-9dab-3040-80f6-e98703b94d4b/

UR - http://www.scopus.com/inward/record.url?scp=85108029058&partnerID=8YFLogxK

U2 - 10.1088/1361-6595/abda9e

DO - 10.1088/1361-6595/abda9e

M3 - статья

VL - 30

JO - Plasma Sources Science and Technology

JF - Plasma Sources Science and Technology

SN - 0963-0252

IS - 5

M1 - 055015

ER -