The striplastron: A new circular stripline microwave launcher for plasma generation in capillary tubes

Until now, microwave plasmas could be ignited in small capillary tubes (inner diameter less than 1 mm) by generating surface waves propagating along their dielectric surfaces using mainly surfatron launchers or stripline-based launchers, such as "split-ring resonators." This work presents a novel launcher, which is called the "striplastron," because it is halfway between surfatrons and stripline launchers. It is a circular stripline directly excitated by a microcoaxial cable. Compared with the surfatron, it is smaller and the part of the plasma hidden by the launcher is limited to its thickness (∼1-2 cm). Moreover, its frequency response presents an intense and large resonance. Eventually, its geometry could allow the simultaneous ignition of several microplasmas in capillaries arranged in parallel, which could be very interesting for applications, such as the use of multi-tube microplasmas as metamaterials.