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High-density nitrogen plasma was produced using a high-power pulsed power modulator to sputter titanium targets for the preparation of titanium nitride film. The high-power pulsed sputtering discharge unit consisted of two targets facing each other with the same electrical potential. The titanium target plates were used as target materials with dimensions of 60 mm length, 20 mm height, and 5 mm thickness. The gap length was set to be 10 mm. The magnetic field was created with a permanent magnet array behind the targets. The magnetic field strength at the gap between the target plates was 70 mT. The electrons were trapped by the magnetic and electric fields to enhance the ionization in the gap. The nitrogen and argon gases were injected into the chamber with 4 Pa gas pressure. The applied voltage to the target plates had an amplitude from −600 V to −1000 V with 600 μs in pulse width. The target current was approximately 10 A with the consumed power of 13 kW. The discharge sustaining voltage was almost constant and independent of the applied voltage, in the same manner as the conventional normal glow discharge. The ion density and electron temperature at the surface of the ionization region were obtained as 1.7 × 1019 m−3 and 3.4 eV, respectively, by the double probe measurements. The vertical distribution of ion density and electron temperature ranged from 1.1 × 1017 m−3 (at 6 cm from the target edge) to 1.7 × 1019 m−3 and from 2.4 eV (at 6 cm from the target edge) to 3.4 eV, respectively. From the emission spectra, the intensities of titanium atoms (Ti I), titanium ions (Ti II), and nitrogen ions (N2+) increased with increasing input power. However, the intensities ratio of Ti II to Ti I was not affected by the intensities from N2+. [ABSTRACT FROM AUTHOR]

The effects of an AC electric field on ice nucleation temperature and nucleation rate were investigated by freezing distilled water while exposing it to varied AC electric field strengths and frequencies. To eliminate the influence of ion injections and electric field concentrations at a metal electrode surface on ice nucleation, distilled water filled in resin cuvettes are used as samples. The samples are exposed to AC electric field induced by parallel plate electrodes placed outside of the cuvettes. The cuvettes and parallel plate electrodes placed in a freezer with an inside temperature fixed at −15°C. The electric field strength in the sample is 2 or 7.5 kV/m and frequency varies from 50 Hz to 10 kHz. The ice nucleation temperature and the nucleation rate of distilled water increase with increasing the electric field strength and the frequency. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The recent trend in thin film deposition is to prepare ceramic films capable of enduring violent environments, such as corrosive pollutant gases with high temperatures. Different kinds of plasma species existing in the same space are advantageous in order to facilitate a reactive deposition between the gaseous and metallic species. In this paper, we study a carbon shunting arc that triggers a gas discharge using a positively biased electrode. An electrode with a positive voltage of up to 500 V was set nearby the carbon shunting arc source. Nitrogen, methane, or argon was used as an ambient gas. The induced plasma was generated with a time delay from the moment of the generation of the shunting arc. The electrical and optical characteristics of the discharge were studied. The onset time of the induced plasma as a function of the ambient gas pressure has a Paschen-like V-shaped characteristic. The generated plasma includes both carbon and gaseous species. At the surface of the positively biased electrode, both spectrum emissions of carbon and gaseous species are observed, by which the plasma is confirmed to be mixed. This is based on the spectrum observation in addition to the change in the color of the plasma. A shunting arc is an easy method used in generating a hybrid plasma consisting of metallic (including carbon) and gaseous species. This method promises to efficiently prepare ceramic films by reactive deposition. This method is simple, and both plasma species, i.e., those of metal and gas particles, are easily mixed. The carbon shunting arc plasma plays both the roles of supplying the carbon species and triggering a gaseous plasma as an induced plasma. Index Terms--Arc discharge, emission spectrum, hybrid plasma, Paschen's law, shunting arc discharge.