We report extensive experimental data on electron emission from lead-zirconate-titanate ferroelectric ceramics. A 1-2 MV/m pulse is applied to a gridded ferroelectric cathode and diode currents of up to 120 A/cm 2 are measured across an A-K gap of 5ϫ10 Ϫ2 m, with the anode at 35 kV. Both the current and the anode voltage pulse duration may extend to several microseconds. The measurements extend previously reported data by nearly two orders of magnitude in the diode voltage and by a factor of more than 3 in the diode spacing. Two major regimes of operation were identified. In the first ϳ1 s the ferroelectric cathode controls the electron flow through the diode. Beyond this time plasma effects dominate the current flow. The results are of importance to the development of novel cathodes for high current electron beam generation.
Electron paramagnetic resonance spectroscopy is used to observe hydroxyl radicals produced by an atmospheric pressure nonthermal plasma device at distances greater than 1 m from the discharge. The plasma device is an indirect treatment setup with closed loop airflow and hydrogen peroxide additives that is effective in deactivating bacteria on time scales of seconds. The generation of the detected hydroxyl radicals is shown to occur in secondary chemical processes near the point of delivery of the plasma treated air stream. The production of hydroxyl radicals is correlated with humidity of the air stream and ability to lyse bacterial membranes. The overall mechanisms of bacteria inactivation are found to be a combinatorial effect of effluent species. The results indicate the feasibility of selective plasma induced free radical delivery for biomedical applications even in the case of short-lived species like the hydroxyl radical.
PIC simulations of post-pulse field reversal and secondary ionization in nanosecond argon discharges To cite this article: H Y Kim et al 2018 Plasma Sources Sci. Technol. 27 055011 View the article online for updates and enhancements. Related content Kinetic simulation of direct-current driven microdischarges in argon at atmospheric pressure Ya Zhang, Wei Jiang and Annemie Bogaerts-Numerical analyses of hydrogen plasma generation by nanosecond pulsed high voltages at near-atmospheric pressure Chieh-Wen Lo and Satoshi Hamaguchi-Advanced PIC-MCC simulation for the investigation of step-ionization effect in intermediate-pressure capacitively coupled plasmas
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