Growth Of Electron Temperature Research Articles

PLASMA PARAMETERS AND REACTIVE-ION ETCHING KINETICS OF ZnO IN HYDROGEN BROMIDE: THE INFLUENCE OF INERT CARRIER GAS

This work discusses the influence of inert carrier gases, Ar and He, on both gas-phase plasma characteristics and ZnO etching rate under typical reactive-ion etching conditions in the hydrogen bromide environment. Plasma diagnostics by Langmuir probes and 0-dimensional plasma modeling allowed one to compare how the content of given carrier gas does influence electrons-and ions-related plasma parameters, kinetics and densities of plasma active species. It was found that the transition toward Ar- or He-rich plasmas a) causes the growth of electron temperature (due to lower electron energy losses in collisions with atomic species); b) reduces plasma electronegativity; and c) results in opposite changes in both ion density and ion flux. The last phenomenon is due to opposite changes in total ionization rates determined by sufficient difference in ionization rate coefficients for Ar and He atoms. Important features of HBr + Ar plasma at 0–80% Ar are also the slower-than-linear fall of Br atom density (due to the intensification of electron impact dissociation for both HBr and Br2 molecules) as well as an increase in H atom density (due to decreasing their loss rate in gas-phase reactions). Etching experiments indicated that the ZnO etching rate is mostly contributed by the ion-assisted chemical reaction while the reaction rate decreases faster compare with the Br atom flux. The corresponding decrease in the effective reaction probability may be related to changes in both ion bombardment intensity and hydrogen passivation effect. For citation: Efremov A.M., Smirnov S.A., Betelin V.B., Kwon K.-H. Plasma parameters and reactive-ion etching kinetics of ZnO in hydrogen bromide: the influence of inert carrier gas. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 12. P. 86-95. DOI: 10.6060/ivkkt.20246712.7081.

Peculiarities of electrode biasing experiments on the T-10 tokamak in regimes with Ohmic and ECR heating

Two types of electrode biasing H-mode were observed on the T-10 tokamak in regimes with electron–cyclotron resonant heating (ECRH). These types differ mainly by the dynamics of the electron temperature. Both types are characterized by a strong (130 V cm−1) radial electric field formation, a decrease of Dα emission intensity, a rise of line-average plasma density and an increase in energy confinement time. However, distinguishing features of the type II H-mode are a time delay of 70–80 ms in the electron temperature growth, a slower increase of the plasma density, and a weak drop of Dα intensity. The differences between the two types of biased H-mode are likely to be connected with the conditioning of the vacuum chamber.

Plasma buildup by short-pulse high-power microwaves

The buildup of a plasma produced by short-pulse (0.05–1.2 μs), high-power (60–100 kW) microwaves is studied in a pressure range of 10 mTorr–10 Torr, by measurements of the temporal variation of the current and the optical intensity. The plasma is produced in a cylindrical tube and confined by a minimum-B field. The buildup of the electron current and the optical intensity are found to continue beyond the end of the pulse, for a few to tens of μs depending upon the pressure, and a minimum in their peak values and buildup times occur around 1 Torr. Increase in microwave pulse duration increases the buildup rate and peak current, whereas the pulse repetition frequency (10–500 Hz) has only a weak influence. The results are discussed from the growth of electron temperature during the pulse, and the following plasma evolution after the end of pulse. Collisional wave absorption, electron cyclotron heating, and diffusion are found to play important roles in plasma production and maintenance over the pressure range.

Charged particle distributions and heat transfer in a discharge between geometrically dissimilar electrodes: From breakdown to steady state

The low-current electric discharge from a fine wire anode to a planar cathode in atmospheric pressure air is numerically simulated from high-voltage prebreakdown through electron temperature growth, then ionization and consequent current growth to steady state, limited by a ballast resistor in the external circuit. Conservation of number (mass) for ions and electrons, Gauss’ law for the self-consistent electric field, and energy conservation for electrons have been solved from breakdown to steady state in a body fitted coordinate system generated specifically for these two geometrically dissimilar electrodes. To facilitate the discussion of the results, the discharge has been categorized under (a) electron acceleration period, (b) charged particle generation period, (c) current increase and voltage drop period, and (d) current and voltage stabilization period. Results are given for transient electron, ion, and temperature distributions in the gap as well as current growth and voltage drop across the gap. Heat flux from the discharge to the wire is calculated. The numerical simulations were compared with experiments performed under the same conditions on a wire bonding machine with very close correspondence.

The surface explosion of electron temperature due to microwave resonant plasma heating

The explosive growth of electron temperature, produced by microwave heating of a collisional magnetoplasma in the vicinity of Langmuir resonance, is illustrated. This explosion is localized near by the irradiated surface of plasma volume. Such effect is stipulated by an external magnetic field, herein this field may be weak enough.