Eur. Phys. J. D (2016) 70: 30
https://doi.org/10.1140/epjd/e2016-60445-x

Regular Article

Gas breakdown and plasma impedance in split-ring resonators^*

Electrical and Computer Engineering, Tufts University, Medford, MA 02155, USA

^a e-mail: alan.hoskinson@tufts.edu

Received: 31 July 2015
Received in final form: 24 November 2015
Published online: 9 February 2016

Abstract

The appearance of resonant structures in metamaterials coupled to plasmas motivates the systematic investigation of gas breakdown and plasma impedance in split-ring resonators over a frequency range of 0.5−9 GHz. In co-planar electrode gaps of 100 μm, the breakdown voltage amplitude decreases from 280 V to 225 V over this frequency range in atmospheric argon. At the highest frequency, a microplasma can be sustained using only 2 mW of power. At 20 mW, we measure a central electron density of 2 × 10²⁰ m^-3. The plasma-electrode overlap plays a key role in the microplasma impedance and causes the sheath impedance to dominate the plasma resistance at very low power levels.