Global models of pulse-power-modulated high-density, low-pressure discharges

Lieberman, M. A.; Ashida, Sumio

doi:10.1088/0963-0252/5/2/006

Cited by 243 publications

(185 citation statements)

References 25 publications

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“…On a time scale of 100 µs after plasma ignition the electron temperature and electron density reach steady state [40][41][42] . Therefore, it is assumed that the measured T e and n e of the steady state plasmas are also valid for the pulsed plasmas for t > 100 µs.…”

Section: Resultsmentioning

confidence: 99%

“…Within a time scale of less than 10 µs the electron temperature decreases to less than 1 eV (see Refs. 40,41 ) so that plasma electrons are no longer able to dissociate or ionize gas species. Therefore, the afterglow measurements of the present work show only the loss process of the radicals.…”

Section: Resultsmentioning

confidence: 99%

“…In the plasma afterglow N atoms are no longer generated from the electron-induced dissociation of N 2 since the energy of the electrons drops sharply within a few µs after switching off the rf power 40,41 . The loss process, though, takes place in the millisecond range.…”

Section: A Theoretical Description Of the Wall Loss Timementioning

confidence: 99%

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Wall loss of atomic nitrogen determined by ionization threshold mass spectrometry

Sode

Schwarz-Selinger

Jacob

et al. 2014

Journal of Applied Physics

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In the afterglow of an inductively coupled N 2 plasma relative N atom densities are measured by ionization threshold mass spectrometry (ITMS) as a function of time in order to determine the wall loss time t wN from the exponential decay curves. The procedure is performed with two mass spectrometers on different positions in the plasma chamber. t wN is determined for various pressures, i.e., for 3.0, 5.0, 7.5, and 10 Pa. For this conditions also the internal plasma parameters electron density n e and electron temperature T e are determined with the Langmuir probe and the rotational temperature T N 2 rot of N 2 is determined with the optical emission spectroscopy. For T N 2 rot a procedure is presented to evaluate the spectrum of the transition v' = 0 → v" = 2 of the second positive system (C 3 Π u → B 3 Π g ) of N 2 . With this method a gas temperature of 610 K is determined. For both mass spectrometers an increase of the wall loss times of atomic nitrogen with increasing pressure is observed. The wall loss time measured with the first mass spectrometer in the radial center of the cylindrical plasma vessel increases linearly from 0.31 ms for 3 Pa to 0.82 ms for 10 Pa. The wall loss time measured with the second mass spectrometer (further away from the discharge) is about 4 times higher. A model is applied to describe the measured t wN .The main loss mechanism of atomic nitrogen for the considered pressure is diffusion to the wall. The surface loss probability β N of atomic nitrogen on stainless steel was derived from t wN and is found to be 1 for the present conditions. The difference in wall loss times measured with the mass spectrometers on different positions in the plasma chamber is attributed to the different diffusion lengths.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Wall loss of atomic nitrogen determined by ionization threshold mass spectrometry

Sode

Schwarz-Selinger

Jacob

et al. 2014

Journal of Applied Physics

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“…This parameter W is often used and given in the literature for high-energy electron beams [20] but it can be defined for gas discharges in general [21,22].…”

Section: Self-sustainment Conditionmentioning

confidence: 99%

“…For our HCD, the total energy per electron-ion pair consists of different contributions due to collisions and transport [21]:…”

Section: Self-sustainment Conditionmentioning

confidence: 99%

Analytical model of a longitudinal hollow cathode discharge

Hagelaar¹,

Mihailova²,

Dijk³

2010

J. Phys. D: Appl. Phys.

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This paper presents a simple analytical model of a longitudinal hollow cathode discharge used in metal vapor lasers. The model describes the principle relations between the voltage, current, plasma density, and the axial structure of the discharge. Contrary to standard DC discharges, this discharge does not require electron multiplication in the cathode fall to produce ions, but rather to satisfy the electron energy balance. A self-sustainment condition is obtained from the energy balance per electron-ion pair. From this, it follows that there is a maximum voltage at which the cathode fall thickness tends to zero and the current density tends asymptotically to infinity. The discharge develops axial non-uniformity and an axial electric field in order to evacuate the created electrons to the anode, such that the characteristic time for transport losses is the same for electrons as for ions. The axial profiles of the current density, plasma density, and potential are obtained from the electron continuity equation. It is shown that additional energy absorption from the axial field, similar to electron heating in DC positive columns, modifies the self-sustainment condition and thus leads to a shift in the voltage-current characteristic, depending on the cathode length.Confidential: not for distribution.

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Diagnostics of a Chemically Active, Pulsed Microwave Plasma for Deposition of Quartz‐like Films

Brockhaus

Behle

Georg

et al. 1999

Contrib. Plasma Phys.

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A remote microwave plasma has been used for the deposition of scratch-resistant quartz-like films. Process gases are argon, oxygen, and hexamethyl-disiloxane. Input power is modulated and the effects on the plasma as well as on the deposition process are studied by means of various diagnostic methods. The film deposition rate is slightly reduced under most conditions but film quality (i.e., cluster size, roughness, scratch resistance) may be improved. A precursor has been identified by mass spectrometric measurements. Its relation to volatile oxides is discussed. The atomic oxygen density and the electron density are determined temporally-resolved. By a suitable choice of the pulse frequency the time-averaged densities of both species can be significantly enhanced as compared to the continuous case. Consideration of the plasma power balance explains how electron density and temperature are influenced by pulsing. It is concluded that the optimum pulse frequency has to be matched to the electron loss rate which mainly depends on the geometrical dimensions of the process chamber.

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Global models of pulse-power-modulated high-density, low-pressure discharges

Cited by 243 publications

References 25 publications

Wall loss of atomic nitrogen determined by ionization threshold mass spectrometry

Wall loss of atomic nitrogen determined by ionization threshold mass spectrometry

Analytical model of a longitudinal hollow cathode discharge

Diagnostics of a Chemically Active, Pulsed Microwave Plasma for Deposition of Quartz‐like Films

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