Similarity of capacitive radio-frequency discharges in nonlocal regimes

Fu, Yangyang; Zheng, Bocong; Zhang, Peng; Fan, Qi Hua; Verboncoeur, John P.; Wang, Xinxin

doi:10.1063/5.0022788

Cited by 21 publications

(23 citation statements)

References 76 publications

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“…The sudden increase in the ratio of energetic electrons in the sustained plasma indicates that the plasma discharge mode transition occurs from the α to the γ mode. The results of Fu et al [11,24] validate the discharge mode transition in our experiment. Fu et al [11,24] reported that the similarity law was identified in similar discharge structures through driving frequency scaling.…”

Section: B Change In the Electron Temperaturesupporting

confidence: 87%

“…The results of Fu et al [11,24] validate the discharge mode transition in our experiment. Fu et al [11,24] reported that the similarity law was identified in similar discharge structures through driving frequency scaling. It was shown that the electron energy probability function (EEPF) overlapped when the driving frequency was varied in the α mode, demonstrating that in a similar discharge mode, the proportion of energetic electrons is maintained.…”

Section: B Change In the Electron Temperaturesupporting

confidence: 87%

“…The EEPF has a more pronounced profile in the high-energy region, describing both the increase in the proportion of energetic electrons and high electron temperature. The simulation results of Fu et al [11,24] verified that many high-energy electrons are generated in the other discharge mode (different from the α mode) where the similarity is violated, confirming that the discharge mode transition occurs in our experiment. Lee et al [13,14,16] intuitively explained that such a transition is the discharge mode transition from the α mode to γ mode in terms of electron confinement (mentioned in the introduction section).…”

Section: B Change In the Electron Temperaturesupporting

confidence: 85%

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Mode transition ($α-γ$) and hysteresis in microwave-driven low-temperature plasmas

Kim¹,

Nam²,

Lee³

et al. 2022

Preprint

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We discovered a hysteresis in a microwave-driven low-pressure argon plasma during gas pressure change across the transition region between α and γ discharge modes. The hysteresis is manifested in that the critical pressure of mode transition depends on the direction of pressure change. As a corollary, the plasma would attain different discharge properties under the same operating parameters (pressure, power, and gas composition), suggesting a bi-stability or existence of memory effect. Analysis of the rotational and vibrational temperatures measured from the OH (A-X) line emissions shows that the hysteresis is mainly due to the fast gas heating in the γ-mode leading to a smaller neutral density than that of the α-mode. When increasing the gas pressure, the γ-mode discharge maintains a relatively higher temperature and lower neutral density, and thus, it requires a higher operating pressure to reach the α-mode. On the other hand, decreasing the pressure while maintaining α-mode, the transition to γ-mode occurs at a lower pressure than the former case due to a relatively higher neutral density of α-mode discharge. This interpretation is supported by the fact that the hysteresis disappears when the plasma properties are presented with respect to the neutral gas density instead of pressure.

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Section: B Change In the Electron Temperaturesupporting

confidence: 87%

Section: B Change In the Electron Temperaturesupporting

confidence: 87%

Section: B Change In the Electron Temperaturesupporting

confidence: 85%

See 1 more Smart Citation

Mode transition ($α-γ$) and hysteresis in microwave-driven low-temperature plasmas

Kim¹,

Nam²,

Lee³

et al. 2022

Preprint

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show abstract

“…Such conditions are most prominent in weakly collisional settings, e.g., at low pressures where the mean free path of the charged particles (typically of the electrons) can be comparable or even longer than the dimensions of the system. Under such conditions, the transport has a nonlocal character [2][3][4][5][6] and although continuum (fluid) approaches can capture this phenomenon to some extent, it is usually achieved by including the corresponding Energy/Velocity Distribution Function (EDF/VDF) and nonlocal closure of the equations as an input to the model [7]. Particle methods, on the other hand, do not require any assumptions of this kind and provide the EDF/VDF as a result of the calculations.…”

Section: Introductionmentioning

confidence: 99%

eduPIC: an introductory particle based code for radio-frequency plasma simulation

Donko,

Derzsi,

Vass

et al. 2021

Preprint

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Particle based simulations are indispensable tools for numerical studies of charged particle swarms and low-temperature plasma sources. The main advantage of such approaches is that they do not require any assumptions regarding the shape of the particle Velocity/Energy Distribution Function (VDF/EDF), but provide these basic quantities of kinetic theory as a result of the computations. Additionally, they can provide, e.g., transport coefficients, under arbitrary time and space dependence of the electric/magnetic fields. For the self-consistent description of various plasma sources operated in the low-pressure (nonlocal, kinetic) regime, the Particle-In-Cell simulation approach, combined with the Monte Carlo treatment of collision processes (PIC/MCC), has become an important tool during the past decades. In particular, for Radio-Frequency (RF) Capacitively Coupled Plasma (CCP) systems PIC/MCC is perhaps the primary simulation tool these days. This approach is able to describe discharges over a wide range of operating conditions, and has largely contributed to the understanding of the physics of CCPs operating in various gases and their mixtures, in chambers with simple and complicated geometries, driven by single-and multi-frequency (tailored) waveforms. PIC/MCC simulation codes have been developed and maintained by many research groups, some of these codes are available to the community as freeware resources. While this computational approach has already been present for a number of decades, the rapid evolution of the computing infrastructure makes it increasingly more popular and accessible, as simulations of simple systems can be executed now on personal computers or laptops. During the past few years we have experienced an increasing interest in lectures and courses dealing with the basics of particle simulations, including the PIC/MCC technique. In a response to this, this paper (i) provides a tutorial on the physical basis and the algorithms of the PIC/MCC technique and (ii) presents a basic (spatially one-dimensional) electrostatic PIC/MCC simulation code, whose source is made freely available in various programming languages. We share the code in C/C++ versions, as well as in a version written in Rust, which is a rapidly emerging computational language. Our code intends to be a "starting tool" for those who are interested in learning the details of the PIC/MCC technique and would like to develop the "skeleton" code further, for their research purposes. Following the description of the physical basis and the algorithms used in the code, a few examples of results obtained with this code for single-and dual-frequency CCPs in argon are also given.

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“…The primary computational tool for these investigations has been the Particle-in-Cell/Monte Carlo Collisions (PIC/MCC) simulation. [55][56][57][58] This particle based approach is fully capable to capture kinetic effects, 59 therefore is well suited for the description of plasma sources operated at low pressures where non-local particle transport [60][61][62][63] appears. An analytical model 27 based on the voltage balance of the discharge has aided the understanding of the observations.…”

Section: Introductionmentioning

confidence: 99%

Self-bias voltage formation and charged particle dynamics in multi-frequency capacitively coupled plasmas

Masheyeva¹,

Dzhumagulova²,

Myrzaly³

et al. 2021

Preprint

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Similarity of capacitive radio-frequency discharges in nonlocal regimes

Cited by 21 publications

References 76 publications

Mode transition ($α-γ$) and hysteresis in microwave-driven low-temperature plasmas

Mode transition ($α-γ$) and hysteresis in microwave-driven low-temperature plasmas

eduPIC: an introductory particle based code for radio-frequency plasma simulation

Self-bias voltage formation and charged particle dynamics in multi-frequency capacitively coupled plasmas

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