Resonant microwaves probing acoustic waves from an RF plasma jet

Platier, Bart; Staps, T. J. A.; Hak, Ccjm Constant; Beckers, JL Jozef; IJzerman, Wilbert L.

doi:10.1088/1361-6595/ab7d8e

Cited by 9 publications

(15 citation statements)

References 29 publications

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“…Please consult appendix A.2 for the specific equations used for the calculation of the (additional) electron density and the (change in) effective collision frequency caused by the discharge and the laser photodetachment events. The time-resolved measurement scheme to determine the resonance frequency and quality factor was deployed previously at atmospheric pressure to study pulsed high-voltage discharges in nitrogen [28] and RF discharges in helium interacting with ambient air [29,30]. From an experimental point of view, first, microwave power was introduced via an antenna into the cavity to excite the TM 010 resonant mode.…”

Section: Methodsmentioning

confidence: 99%

Laser-induced photodetachment of negative oxygen ions in the spatial afterglow of an atmospheric pressure plasma jet

Staps

Donders

Platier

et al. 2022

Plasma Sources Sci. Technol.

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Negative ions are an important constituent of the spatial afterglow of atmospheric pressure plasmas, where the fundamental plasma-substrate interactions take place that are vital for applications such as biomedicine, material synthesis, and ambient air treatment. In this work, we use laser-induced photodetachment to liberate electrons from negative ions in the afterglow region of an atmospheric pressure plasma jet interacting with an argon-oxygen mixture, and microwave cavity resonance spectroscopy (MCRS) to detect the photodetached electrons. This diagnostic technique allows for the determination of the electron density and the eﬀective collision frequency before, during and after the laser pulse was shot through the measurement volume with nanosecond time resolution. From a laser saturation study, it is concluded that O− is the dominant negative ion in the afterglow. Moreover, the decay of the photodetached electron density is found to be dominantly driven by the (re)formation of O− by dissociative attachment of electrons with O2. As a consequence, we identiﬁed the species and process responsible for the formation of negative ions in the spatial afterglow in our experiment.

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Section: Methodsmentioning

confidence: 99%

Laser-induced photodetachment of negative oxygen ions in the spatial afterglow of an atmospheric pressure plasma jet

Staps

Donders

Platier

et al. 2022

Plasma Sources Sci. Technol.

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“…The resonance frequency was obtained post-measurement by fitting the reflected microwave power signal, P refl , and determining the minimum of this fit. The same approach with a moving average filter (temporal width = 1 µs) as used in [11,14] was employed here to increase the spectral resolution to 2 × 10 2 Hz.…”

Section: Data Acquisition Systemmentioning

confidence: 99%

“…The diffusive mechanisms governing the plasma decay depend, among others, on the electron mean free path and the initial plasma dimensions [9]. Recently, the sensitivity of MCRS has been increased [11][12][13][14][15], enabling the exploration of a third decay regime [11]. This provided in-depth insight into the lowdensity electron dynamics of an EUV-induced argon plasma, late in the afterglow.…”

Section: Introductionmentioning

confidence: 99%

Influence of a magnetic field on an extreme ultraviolet photon-induced plasma afterglow

Limpens

Platier

Lassise

et al. 2021

J. Phys. D: Appl. Phys.

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Understanding extreme ultraviolet (EUV) photon-induced plasma dynamics is key to increasing the lifetime of the new generation of lithography machines. The plasma decay times were determined by means of a non-destructive microwave method, microwave cavity resonance spectroscopy, for unmagnetized and magnetized EUV photon-induced plasma afterglows with the argon pressure ranging from 0.002 to 10 Pa. As a result of an external magnet with a magnetic field strength of (57 ± 1) mT, the plasma decay times were extended by two orders of magnitude. Good agreement was found between these measured plasma decay times and four diffusion models, i.e. the ion acoustic, ambipolar, classical-collision, and Bohm’s diffusion model.

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“…Platier et al, reported the utilization of microwave cavity resonance spectroscopy to estimate the electron density and effective electron collision frequency in the spatial afterglow of a 13.56 MHz pulsed driven atmospheric pressure helium plasma jet. [ 31 ] Modulation frequency was set between 125 and 8000 Hz, and the duty cycle was varied from 40% to 0.625%, and during the “plasma on” phase, values of 1.7 ± 0.3 × 10 18 m −3 for the electron density and 0.12 ± 0.01 THz for the electron collision frequency were found. In another study, the effect of pulse modulation on the ionic content of a 13.56 MHz helium plasma needle was explored using molecular beam mass spectrometry.…”

Section: Introductionmentioning

confidence: 99%

Influence of pulse modulation frequency on helium RF atmospheric pressure plasma jet characteristics

Mahreen

Prakash

Kar

et al. 2022

Contributions to Plasma Physics

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This work investigates the influence of pulse modulation frequency ranging from 50 Hz–10 kHz on the helium RF atmospheric pressure plasma jet's fundamental characteristics. The impact of modulation frequency on plasma jet discharge behaviour, geometrical variation, reactive species emission, and plasma parameters (gas temperature Tg, electron excitation temperature Texc, and electron density (ne)) are studied using various diagnostics such as optical imaging, emission spectra, and thermal diagnostic. From the experiments, it is observed that operating the plasma jet at low pulse modulation frequencies (around 50 Hz) provides enhanced plasma dimensions, higher electron densities and greater optical emission from reactive species (viz., He I, O, OH, N2+, etc.) as compared to the higher modulation frequencies. Besides the low power consumption, three times less gas temperature of the modulated plasma jet than the continuous wave mode makes it more advantageous for the applications. Moreover, the influence of duty cycle (D) and applied RF power (P) on the plasma jet characteristics are also discussed. It is found that 10–40% duty cycle operation provides the most favourable attributes. More importantly, the concern of shorter plasma length in RF plasma jets is overcome by operating at 10–20% duty cycle with increased applied power. This work thoroughly characterizes helium atmospheric pressure RF plasma jet with a wide range of pulse mode operating parameters, which could help to select appropriate operating conditions for various industrial and biomedical applications.

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Resonant microwaves probing acoustic waves from an RF plasma jet

Cited by 9 publications

References 29 publications

Laser-induced photodetachment of negative oxygen ions in the spatial afterglow of an atmospheric pressure plasma jet

Laser-induced photodetachment of negative oxygen ions in the spatial afterglow of an atmospheric pressure plasma jet

Influence of a magnetic field on an extreme ultraviolet photon-induced plasma afterglow

Influence of pulse modulation frequency on helium RF atmospheric pressure plasma jet characteristics

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