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Driving frequency effect on discharge parameters and higher harmonic generation in capacitive discharges at constant power densities

Sharma, Sarveshwar orcid logoORCID: 0000-0002-0642-0247, Sirse, Nishant orcid logoORCID: 0000-0002-7063-4100, Kuley, Animesh orcid logoORCID: 0000-0003-2325-6597, Sen, Abhijit and Turner, Miles M. orcid logoORCID: 0000-0001-9713-6198 (2020) Driving frequency effect on discharge parameters and higher harmonic generation in capacitive discharges at constant power densities. Journal of Physics D: Applied Physics, 54 (5). ISSN 0022-3727

Abstract
Very high frequency (VHF) driven capacitive discharges are now being increasingly adopted for plasma-based materials processing due to their high processing rates and lower substrate damage. Past studies related to complex plasma dynamics and higher harmonics generation in such systems were limited to constant voltage/current conditions, whereas, industrial systems are mostly driven by constant power density sources. In the present study, using particle-in-cell (PIC) simulation, we explore the dynamics of collisionless symmetric capacitive discharges that is operated at constant power densities. Our focus is on the effect of the driving frequency on the discharge parameters like the electron density/temperature, the electron energy distribution function (EEDF), the ion energy distribution function (IEDF), and the generation of higher harmonics in the device. The simulations are performed for a driving frequency from 27.12-100 MHz in argon plasma at a gas pressure of 1 Pa and for two values of the power density, namely, 2 kW/m3 and 20 kW/m3. It is observed that the required discharge voltage for maintaining constant power density decreases and discharge current increases with an increase in the driving frequency. A transition frequency is observed at both power densities. The density decreases (electron temperature increases) before the transition frequency and the trend is reversed after crossing the transition frequency. The EEDF shows an enhancement in the population of the mid-energy range of electrons as the driving frequency increases up to the transition frequency thereby changing the shape of EEDF from bi-Maxwellian to nearly Maxwellian, and then transforms into a nearly bi-Maxwellian at higher driving frequencies. The IEDF at the electrode surface shows bimodal behaviour at a lower driving frequency, becoming more pronounced at a power density of 20 kW/m3, and then turning into a single energy peak. The corresponding maximum ion energy is found to decrease with driving frequency.
Metadata
Item Type:Article (Published)
Refereed:Yes
Additional Information:Article number: 055205
Subjects:Physical Sciences > Plasmas
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Physical Sciences
Research Initiatives and Centres > National Centre for Plasma Science and Technology (NCPST)
Publisher:Institute of Physics
Official URL:https://dx.doi.org/10.1088/1361-6463/abc11b
Copyright Information:© 2020 IOP Publishing Ltd
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License
Funders:Board of Research in Nuclear Sciences (BRNS Sanctioned No. 39/14/05/2018-BRNS), Science and Engineering Research Board EMEQ program (SERB Sanctioned No. EEQ/2017/000164), Infosys Foundation Young Investigator grant, National Science Academy (INSA) for their support under the INSA Senior Scientist Fellowship scheme
ID Code:27104
Deposited On:09 May 2022 13:41 by Miles Turner . Last Modified 09 May 2022 15:38
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