A pulsed discharge is introduced between two sequential pulse-modulated radio frequency glow discharges in atmospheric helium. The dependence of radio frequency discharge ignition on pulsed discharge intensity is investigated experimentally with the pulse voltage amplitudes of 650, 850, and 1250 V. The discharge characteristics and dynamics are studied in terms of voltage and current waveforms, and spatial-temporal evolution of optical emission. With the elevated pulsed discharge intensity of two orders of magnitude, the ignition of radio frequency discharge is enhanced by reducing the ignition time and achieving the stable operation with a double-hump spatial profile. The ignition time of radio frequency discharge is estimated to be 2.0 μs, 1.5 μs, and 1.0 μs with the pulse voltage amplitudes of 650, 850, and 1250 V, respectively, which is also demonstrated by the spatial-temporal evolution of optical emission at 706 and 777 nm.

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The discharge characteristics and mechanism of pulse modulated radio frequency (RF) atmospheric pressure glow discharge (APGD) are studied using a two-dimensional self-consistent numerical fluid model. The ignition of an RF discharge burst is demonstrated by the increase in RF current amplitude and evolution of the discharge spatial profile from a bell shape to a double-hump shape. With a time interval of 80 µs between two consecutive RF discharge bursts, the electron dissipation after an RF discharge burst is shown, whose reduction slope changes from 1.7 × 1022 m−3s−1 to 9.1 × 1019 m−3s−1 with a time delay. The corresponding electron dissipation mechanism is proposed to be the electron loss due to reactions in the discharge bulk and the drift of electrons across the discharge gap, which explains the continuum and discrete operation modes in pulse modulated RF APGD.

A one-dimensional self-consistent fluid numerical model was developed to study the ignition characteristics of a pulse-modulated (PM) radio-frequency (RF) glow discharge in atmospheric helium assisted by a sub-microsecond voltage excited pulsed discharge. The temporal evolution of discharge current density and electron density during PM RF discharge burst was investigated to demonstrate the discharge ignition characteristics with or without the pulsed discharge. Under the assistance of pulsed discharge, the electron density in RF discharge burst reaches the magnitude of 1.87×10 17 m −3 within 10 RF cycles, accompanied by the formation of sheath structure. It proposes that the pulsed discharge plays an important role in the ignition of PM RF discharge burst. Furthermore, the dynamics of PM RF glow discharge are demonstrated by the spatiotemporal evolution of the electron density with and without pulsed discharge. The spatial profiles of electron density, electron energy and electric field at specific time instants are given to explain the assistive role of the pulsed discharge on PM RF discharge ignition.

The influence of a high voltage sub-microsecond pulsed plasma plume on a radio frequency discharge at atmospheric pressure is studied experimentally. The discharge characteristics and dynamics of pulsed discharge and radio frequency discharge are characterized in terms of voltage and current waveforms and spatio-temporal evolution of discharge. It is found that the plasma bullet generated by pulsed discharge can inject into the radio frequency discharge region with the average travelling speed of 70 km/s. The radio frequency discharge intensity is elevated to be 3 times higher as the plasma bullet penetrating the interelectrode gap of radio frequency discharge. The enhancement is attributed to the injection of energetic electrons by the plasma bullet, which is demonstrated by the temporal evolution of discharge image intensity and optical emission spectroscopy intensity.