Tailored voltage waveforms applied to a capacitively coupled chlorine discharge

• Published in: Plasma sources science & technology 2020-08, Vol.29 (8), p.84004
• Main Authors: Skarphedinsson, G A, Gudmundsson, J T
• Format: Article
• Language: English
• Subjects: capacitively coupled discharge; chlorine; electronegativity; particle-in-cell; tailored waveform
• ISSN: 0963-0252; 1361-6595; 1361-6595
• DOI: 10.1088/1361-6595/aba920

Tailored voltage waveform, composed of a fundamental frequency and the second harmonic, is applied to a capacitively coupled chlorine discharge operated in the pressure range 1-50 Pa. The electronegativity is very high and the electron power absorption is mainly due to drift-ambipolar (DA) electron power absorption within the electronegative core. For operating pressures of 1 and 10 Pa the creation of a dc self-bias and asymmetric response is demonstrated and applied to control the ion bombardment energy while the ion flux on the electrodes remains fixed. However, the available range in mean ion energy is rather limited and the range is significantly narrower than typically observed for electropositive discharges. For operating pressure of 50 Pa it is not possible to control the ion bombardment energy by the phase angle between the fundamental frequency and the second harmonic. At the low pressure of 1 Pa the power absorption by Cl2+ ions dominate, while power absorption by electrons is smaller. At higher operation pressure DA power absorption by electrons dominates. The electric field within the electronegative core is high and not constant within the plasma bulk and exhibits the waveform of the discharge driving voltage for both the single frequency and dual frequency operation.