The sheath effect on the floating harmonic method

Lee, Jaewon; Kim, Kyung-Hyun; Chung, Chin-Wook

doi:10.1063/1.4936347

Cited by 4 publications

(1 citation statement)

References 14 publications

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“…It can be clearly seen that the dependence on V 0 is much more pronounced in case of the electron temperature obtained from i 1ω /i 2ω . This can be explained by the fact, that the ion current is not independent on the probe voltage and therefore some AC ion current is generated, which contributes to the measured current, predominantly to the first harmonic cur rent component i 1ω [29]. Somewhat surprisingly, there is not much difference between the thick and the thin probe in the slope of the trends.…”

Section: Dependence Of the T E And N I Measured By Fhp On The Applied...mentioning

confidence: 91%

Floating harmonic probe measurements in the low-temperature plasma jet deposition system

Zanáška¹,

Hubička²,

Čada³

et al. 2017

J. Phys. D: Appl. Phys.

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The floating harmonic probe is a relatively new plasma diagnostic method, which was proposed for applications at conditions when insulating films are deposited on the probe and, consequently, the classical Langmuir probe method fails. In the floating harmonic probe method a purely sinusoidal AC voltage is applied to the probe constructed in a standard manner via a capacitor. From the spectral components of the measured AC probe current waveforms, the electron temperature and the positive ion density can be obtained. In this contribution we present the comparison of the electron temperature and density acquired by the floating harmonic probe method with those obtained by the classical Langmuir probe. The experiments are performed in the flowing DC discharge in argon. In addition, the results from the floating harmonic probe method obtained during deposition of an insulating iron oxide thin film are shown. All the data is complemented by the qualitative discussion.

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Section: Dependence Of the T E And N I Measured By Fhp On The Applied...mentioning

confidence: 91%

Floating harmonic probe measurements in the low-temperature plasma jet deposition system

Zanáška¹,

Hubička²,

Čada³

et al. 2017

J. Phys. D: Appl. Phys.

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The radio-frequency fluctuation effect on the floating harmonic method

Lee

Kim

et al. 2016

Physics of Plasmas

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The radio-frequency (RF) plasma diagnostics with an electrical probe facing a challenge, because the RF fluctuation oscillates the plasma potential and distorts the current-voltage (I-V) curve. As Langmuir probe is widely used in plasma diagnostics, many researchers have been studying the effect of RF fluctuation on probe and compensation methods. On the other hand, there have not been enough studies on the fluctuation effect on the floating harmonic method. Therefore, we investigated the impact of RF fluctuation on the floating harmonic method theoretically and experimentally. When the electrons are in ideal Maxwellian distribution, the floating potential is negatively shifted by the RF fluctuation, but the fluctuation does not distort I-V curve around the floating potential. However, in practical plasmas, the I-V curve and their harmonic components are distorted. This RF fluctuation effect becomes more significant in a low density plasma with a high impedance sheath. The second harmonic current decreases with the RF fluctuation while the first harmonic current is merely affected. Therefore, the electron temperatures measured with the floating harmonic method under low density plasma with uncompensated probe are overestimated than the results obtained with the compensated probe.

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Compensation of the sheath effects in cylindrical floating probes

Park

Chung

2018

Physics of Plasmas

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In cylindrical floating probe measurements, the plasma density and electron temperature are overestimated due to sheath expansion and oscillation. To reduce these sheath effects, a compensation method based on well-developed floating sheath theories is proposed and applied to the floating harmonic method. The iterative calculation of the Allen-Boyd-Reynolds equation can derive the floating sheath thickness, which can be used to calculate the effective ion collection area; in this way, an accurate ion density is obtained. The Child-Langmuir law is used to calculate the ion harmonic currents caused by sheath oscillation of the alternating-voltage-biased probe tip. Accurate plasma parameters can be obtained by subtracting these ion harmonic currents from the total measured harmonic currents. Herein, the measurement principles and compensation method are discussed in detail and an experimental demonstration is presented.

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The sheath effect on the floating harmonic method

Cited by 4 publications

References 14 publications

Floating harmonic probe measurements in the low-temperature plasma jet deposition system

Floating harmonic probe measurements in the low-temperature plasma jet deposition system

The radio-frequency fluctuation effect on the floating harmonic method

Compensation of the sheath effects in cylindrical floating probes

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