Global model for plasmas generated by electron beams in low-pressure nitrogen

Lock, Evgeniya H.; Fernsler, R. F.; Slinker, S. P.; Singer, I. L.; Walton, Scott G.

doi:10.1088/0022-3727/47/42/425206

Cited by 34 publications

(34 citation statements)

References 53 publications

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“…10 3 Moreover, this ratio would increase with the decreasing of the plasma density. As a result, it can be predicted that the molecular ions must be dominated with the decay of the plasma density in the interested pressure range from 200 Pa to 3000 Pa in this paper and hence the decay of the density can be approximated by equation (5) at low beam current intensities. It was clearly shown from equation (5) that the decease of the electron density was relevant with the initial density but not with the pressure, which was in good accordance with the experimental results.…”

Section: Discussionmentioning

confidence: 90%

Investigations on the time evolution of the plasma density in argon electron-beam plasma at intermediate pressure

Chen¹,

Li²,

Liu³

2017

Plasma Sci. Technol.

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The time evolution of the argon electron-beam plasma at intermediate pressure and low electron beam intensity was presented. By applying the amplitude modulation with the frequency of 20 Hz on the stable beam current, the plasma evolution was studied. A Faraday cup was used for the measurement of the electron beam current and a single electrostatic probe was used for the measurement of the ion current. Experimental results indicated that the ion current was in phase with the electron beam current in the pressure range from 200 Pa to 3000 Pa and in the beam current range lower than 20 mA, the residual density increased approximately linearly with the maximum density in the log-log plot and the fitting coefficient was irrelative to the pressure. And then three kinds of kinetic models were developed and the simulated results given by the kinetic model, without the consideration of the excited atoms, mostly approached to the experimental results. This indicated that the effect of the excited atoms on the plasma density can be ignored at intermediate pressure and low electron beam current intensity, which can greatly simplify the kinetic model. In the end, the decrease of the plasma density when the beam current was suddenly off was studied based on the simplified model and it was found that the decease characteristic at intermediate pressure was approximate to the one at high pressure at low electron beam intensity, which was in good accordance with the experimental results.

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Section: Discussionmentioning

confidence: 90%

Investigations on the time evolution of the plasma density in argon electron-beam plasma at intermediate pressure

Chen¹,

Li²,

Liu³

2017

Plasma Sci. Technol.

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“…Typically, the electron temperature in a gas discharge plasma is 1−4 eV, and the electron energy at the initial stage is only enough to excite a precursor molecule, so its fragmentation takes place only with the neutral particle participation. A feature of a beam plasma is the presence of two groups of electrons in it: the fast electrons with an energy up to several hundred eV and the plasma electrons with a temperature of 0.3−1 eV [7]. The ionization potential of the HMDS molecule is 8.8 eV [8]; therefore, in the presence of the fast electrons in the plasma, the fragmentation process can be intensified to be due to an additional mechanism that starts from the formation of (CH3)3-Si-NH-Si-(CH3) 3+ by electron impact ionization and weakening of chemical bonds in the molecule, which can explain the increased decomposition degree of the precursor molecules with increasing electron energy.…”

Section: Abstract Sicn Coating; Polymer Derived Ceramic; Low-energy Ementioning

confidence: 99%

Investigation of a New Method of the Organosilicon Compounds Activation by a Low-energy Electron Beam for SiCN-coatings Deposition

Men’shakov

Cholakh

2020

e-J. Surf. Sci. Nanotechnol.

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The article describes a new method of organosilicon compounds activation by low energy electron beam for SiCN coatings deposition. The composition of the beam plasma in a hexamethyldisilazane-containing gas medium was studied, and it was shown that the precursor molecules decomposition degree increases with the beam current and nonmonotonically depends on the electron beam energy. The application of a low-energy electron beam for the plasma-chemical vapor decomposition of hexamethyldisilazane and for samples heating up by electron beam to 600°C makes it possible to obtain SiCN-based coatings with a hardness up to 18 GPa and thickness ~1 μm for 1 h.One of the ecological, effective and productive modern methods for silicon carbonitride (SiCN) coatings production is a chemical vapor deposition in organosilicon compounds (OSC) vapors medium by its decomposition in plasma (PECVD) [1]. The main factor determining the unique characteristics of SiCN-coatings (such as high hardness, oxidation resistance, chemical inertness, etc.) are the conditions of its synthesis, so the possibility of a controlled change of various processing parameters is crucial for coatings with desired properties obtaining. Usually a radio frequency discharge is used for plasma activation of the precursor vapors [2]. It is important to control the precursor molecules decomposition degree in order to facilitate the formation of films containing both Si−C and Si−N bonds and, as a result, having high mechanical characteristics. However, when using gas discharges, in fact, the only controlled parameter is the discharge current (or power). An alternative way to generate plasma is to use low-energy electron beams [3]. The advantage of this method is that in the range of electron energies 100−200 eV, which is close to the maximum of electron impact ionization cross section of gas molecules and atoms, the frequency of plasma processes increases, resulting in the formation of ionized and excited particles. In addition, an important advantage of the sources used [4] is the independent control of the emission current and electron energy, pressure and gas medium composition over a wide range, which provides flexible control of the plasma parameters. This method was not previously used for the OSC decomposition.This approach was realized in an electrode system with a two-stage source of a wide (~100 cm 2 ) low-energy electron beam based on a self-heating hollow cathode discharge (SHHC), the design of which was described in detail in [5] (Figure 1). The beam current I b was varied up to 5 A by changing the discharge current in the first stage, electron beam energy varied in the range 50−500 eV. Hexamethyldisilazane [(CH 3 ) 3 Si] 2 NH (hereinafter HMDS) was taken as an OSC precursor. The precursor vapor flow was 2 g h −1 . Argon was used as the plasma-forming gas, which flow was kept constant (40 sccm), the pressure in the chamber was 0.2−0.3 Pa.The OSC molecules decomposition process is determined both by the binding energies between the atoms in the initial mo...

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“…At λ = 574-775 nm, the spectrum reveals three groups of lines which, according to ref. [12], belong to the first positive system (FPS) of molecular nitrogen N 2 . In the breakdown spectrum, only lines of Fe are distinguishable among the metal lines, due to the high percentage of Fe (higher than 70%) in the electrode material (stainless steel) of the gap, and only lines of its neutral atoms.…”

Section: доклады тусура том 19 № 4 2016mentioning

confidence: 99%

Optical radiation in breakdown of the acceleration gap of a forevacuum pressure, wide-aperture, plasma-cathode, pulsed electron source

Бурдовицин¹,

Казаков²,

Medovnik³

et al. 2016

Proceedings of TUSUR

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We have investigated the spectrum of optical radiation during breakdown in the acceleration gap of a wide-aperture, plasma-cathode, pulsed electron source based on a vacuum arc discharge in the forevacuum pressure range (3-20 Pa). The analysis shows that breakdown considerably increases the spectral line intensity and results in additional gas and metal lines. The spectrum is dominated by atomic and molecular lines from the working gas. The presence of metal lines under breakdown conditions suggests that cathode spots arise at the emission electrode, assisting the gas discharge in the acceleration gap.

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Global model for plasmas generated by electron beams in low-pressure nitrogen

Cited by 34 publications

References 53 publications

Investigations on the time evolution of the plasma density in argon electron-beam plasma at intermediate pressure

Investigations on the time evolution of the plasma density in argon electron-beam plasma at intermediate pressure

Investigation of a New Method of the Organosilicon Compounds Activation by a Low-energy Electron Beam for SiCN-coatings Deposition

Optical radiation in breakdown of the acceleration gap of a forevacuum pressure, wide-aperture, plasma-cathode, pulsed electron source

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