Microwave-driven plasmas in Hollow-Core Photonic Crystal Fibres

This paper reports on a novel solution to ignite and maintain micro-plasmas in gas-filled Hollow-Core Photonic Crystal Fibres (HC-PCFs), using CW microwave excitation (2.45 GHz) [1]. The original concept is based on a surfatron, generating argon micro-plasmas of few centimetres in length within a $100\;\mu m$ core-diameter Kagome HC-PCF, at $\sim $1 mbar on-gap gas-pressure using low powers (\textless\ 50 W). Diagnostics of the coupled power evidence high ionization degrees ($\sim $10$^{-2})$, for moderate gas temperatures ($\sim $1300 K at the centre of the fibre, estimated by OES), with no damage to the host structure. This counter intuitive result is studied using a 1D-radial fluid model that describes the charged particle and the electron energy transport, the electromagnetic excitation and the gas heating [2,3]. We analyze the modification of the plasma and the gas heating mechanisms with changes in the work conditions (core diameter, pressure and electron density). \\[4pt] [1] B. Debord et al, ECOC conference Mo.2.LeCervin.5. (2011)\\[0pt] [2] L.L. Alves et al, Phys. Rev. E \textbf{79}, 016403 (2009) \\[0pt] [3] J. Greg\'{o}rio et al, Plasma Sources Sci. Technol. \textbf{21}, 015013 (2012)