Plasma parameters in 40MHz Argon discharge (original) (raw)
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Two Temperatures Components in CCP Argon 13.56-MHz RF Discharge
IEEE Transactions on Plasma Science, 2015
Careful radio frequency (RF) compensation and empirical modeling of Langmuir probe I-V characteristics of argon capacitive coupled asymmetric plasma discharge indicated the existence of two temperature groups of electrons. The new eight free fitting parameters empirical equation suggested has the capability of better detection of any existence of such two temperature electron groups. Analysis shows that the first group of electrons has a low mean temperature that is almost independent of RF power. The second group of electrons is a hightemperature component that seems to increase with increasing RF power. The population contribution of the lower temperature group seems to increase with increasing RF power.
2014
Glow characteristics of capacitive radio frequency discharge with isolated electrodes in atmospheric pressure argon in low-current and high-current modes are determined experimentally and calculated by the hybrid hydrodynamic model. Comparative analysis of obtained experimental data and simulated spatio-temporal distributions of concentrations of discharge plasma electrons and heavy species, mean energy of electrons in the RF barrier discharge enabled interpretation of the discharge structure peculiarities in low-current α, α-γ transition and high-current γ modes.
Electrical characteristics of parallel-plate RF discharges in argon
IEEE Transactions on Plasma Science, 1991
Electrical characteristics have been measured in a parallel-plate, capacitively coupled (E-type), low-pressure, symmetrical RF discharge driven at 13.56 MHz. The discharge voltage, current, and phase shift between them were measured over a very wide range of discharge parameters (gas pressures between 3 mtorr and 3 torr with discharge power between 20 mW and 100 W). From these measurements the discharge impedance components, the power dissipated in the plasma and in the sheaths, the sheath width, and the ion current to the RF electrodes were found over a wide range of discharge conditions. Some of the general relationships between the various measured and determined parameters are discussed. The experimental results presented here can be used as a data base for straightforward comparison with existing RF discharge models and numerical simulations.
Physical Review Letters, 1990
The electron energy distribution function measured with improved energy resolution revealed a large number (=90%) of low-energy electrons having an abnormally low electron temperature (T= 0.3 V) resulting in a considerably lower mean electron energy than found in all published probe measurements in argon rf discharges at 13.56 MHz. With increasing gas pressure an abrupt transition to a hightemperature mode was found. The low-temperature mode and the observed transition are attributed to a change from stochastic to collisional electron heating enhanced by the Ramsauer eA'ect. rf electrode V.
The main properties of microwave argon plasma at atmospheric pressure
Journal of Physics: Conference Series, 2010
Plasma torch sustained by surface wave at atmospheric pressure is theoretically studied by means of 1D model. A steady-state Boltzmann equation in an effective field approximation coupled with a collisional-radiative model for high-pressure argon discharge is numerically solved together with Maxwell's equations for an azimuthally symmetric TM surface wave. The axial dependences of the electrons, excited atoms, atomic and molecular ions densities as well as the electron temperature, the mean power per electron and the effective electron-neutral collision frequency are determined. A strong dependence of the plasma properties on the discharge conditions and the gas temperature is obtained. 1 argon discharge are described. Section 3.3 looks into the self-consistent connection between the former two parts of the modelling. Finally, section 4 shows the results obtained by means of applying the complete model.
Current Applied Physics, 2013
Plasma parameters from the discharge characteristics of a 13.56 MHz capacitively coupled radio frequency Ar plasma are evaluated on the basis of homogeneous discharge model for wide range of operating pressure. The homogeneous discharge model of capacitively coupled radio frequency discharge is modified to take into account the nonlinear plasma series resonance effect. The effect of drift velocity of the electron due to change in radio frequency electric field and operating pressure is also considered. Considerable dependent of plasma parameters on the drift velocity of the electron as well as on the plasma series resonance effect are observed in low pressure. An irregular variation of calculated plasma density with operating pressure is observed, which is reconfirmed with optical emission spectroscopy.
Numerical Model of an Argon Atmospheric Pressure RF Discharge
IEEE Transactions on Plasma Science, 2000
Radio-frequency discharges are known to operate in two different regimes. The α regime of low current density and the γ regime with higher current density. Our recent simulation results suggest that the formation of filaments observed in an atmospheric pressure argon discharge under RF excitation could be triggered by the regime transition α → γ. A unidimensional fluid model taking into account the external circuit shows that above 120 mA/cm 2 , the differential conductivity of the discharge becomes negative with a rapid increase in density which can lead to the formation of filaments. As the transition to the γ regime is due to secondary electrons, this threshold value depends on the secondary emission coefficient. In the γ regime, the instantaneous cathode is sustained by secondary electron emission, which drastically changes the behavior of the discharge. In this paper, we present a numerical analysis of the transition between the two regimes and discuss how this could result in the filamentary mode observed in argon RF discharges.
Pulsed RF discharges, glow and filamentary mode at atmospheric pressure in argon
Plasma Sources Science and Technology, 2007
The properties of a pulsed radio frequency capacitive discharge are investigated at atmospheric pressure in argon. The discharge can operate in two different modes: a homogeneous glow discharge or turn into filaments. By pulsing the 13.56 MHz generator both the filamentary and the glow modes can be selected depending on the pulse width and period. For a 5 µs pulse width (∼70 RF cycles in the pulse), short pulse periods (less than 100 µs) result in a filamentary discharge while long pulse periods (greater than 1 ms) result in a glow discharge.
International Journal of Applied Physics and Mathematics
Low temperature radio frequency plasma is widely used in low temperature plasma processing medium for material processing in many fields including microelectronics, aerospace, and the biology. For proper utilization of the process, it is very much important to know the plasma parameters. In this paper a technique is reported to determine the plasma parameters from the electrical discharge characteristic of a capacitivly couple radio frequency argon plasma. The homogeneous discharge model is modified to make it applicable in low pressure by incorporating the plasma series resonance effect. The effect on the plasma resistance by the change in drift velocity of the electron with rf electric filed is also considered. The electron density and temperature is found to be well agreed with the Langmuir probe diagnostic result, which is in the range of 0.5x10 10 to 4.5x10 10 cm-3 and 1.4 to 1.6 ev for wide range of rf power. Index Terms-Capacitive couple radio frequency plasma, discharge characteristic, homogeneous discharge model, plasma parameters, power balance.
Plasma stratification in radio-frequency discharges in argon gas
Journal of Physics D: Applied Physics, 2020
We conducted experimental studies and computer simulations of standing striations in capacitive coupled plasma in Argon gas. Standing striations were observed at frequencies 3.6, 8.4 and 19.0 MHz, in a pressure range 0.05-10 Torr, tube radius R=1.1 cm, for a certain range of discharge currents (plasma densities). Numerical simulations revealed similar nature of standing striations in CCP and moving striations in DC discharges under similar discharge conditions. Comparison of computer simulations with experimental observations helped clarify the nature of these striations. The non-linear dependence of the ionization rate on electron density is shown to be the main underlying mechanism of the stratification phenomena.