Radio-Frequency Sustainment of Laser Initiated, High-Pressure Air Constituent Plasmas*

In this paper we investigate the feasibility of creating a high‐density ∼ 1012−1014 cm−3, large volume seed plasma in air constituents by laser (300 mJ, 20(±2) ns) preionization of an organic gas seeded in high‐pressure gas mixtures and then sustained by efficient absorption of rf power (1–25 kW pulsed) through inductive coupling of the wave fields. A multi‐turn helical antenna is used to couple radio‐frequency power through a capacitive matching network. A 105 GHz interferometer is employed to obtain the plasma density in the presence of high collisionality utilizing phase shift and amplitude attenuation data. TMAE Plasma decay mechanisms with and without the background gas are examined.