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The hot refractory anode vacuum arc (HRAVA) plasma source was previously developed with a consumed cathode and a refractory anode to reduce the macroparticle (MP) contamination in vacuum arc deposited films. The HRAVA had open cylindrical electrodes and demonstrated that it not only reduced MP sizes and numbers but also converted MP material to plasma, and thus increased the deposition rate. This paper presents a new HRAVA configuration with a double arc between a common water-cooled Cu cathode with two active surfaces and two refractory graphite or tungsten anodes, with the aim of depositing film over a wider area. The arc current in each of the two arcs was 125 A for graphite and 150 A for tungsten. The radially expanding plasma plumes from each of the cathode–anode gaps merged, forming a wider common plasma. Cu films were deposited and over a 150 mm length parallel to the arc axis, while the corresponding length from a single-HRAVA source was only 75 mm. [ABSTRACT FROM AUTHOR]

This paper presents a semi-empirical model for a wire–wire corona reactor driven by a capacitive storage solid-state pulse generator. The reactor electrode system is configured as a checker mesh of potential and grounded threaded electrodes, and the pulse generator is based on a modern magnetic pulse compression topology. This presentation considers the effect of the geometrical parameters of the reactor (the total length of the high-voltage electrode surrounded by its grounded counterparts and the gap between the high-voltage and grounded electrodes) on the operation of the atmospheric pressure streamer plasma system. The model analyzes the discharge processes in the reactor by distinguishing between four phases, each being represented by an equivalent circuit: before the streamer generation, during the primary streamer propagation, after the primary streamers have crossed the interelectrode gaps, and after the plasma conductivity quenching. The new reactor model is realized on the PSpice platform, and the simulations are done using an improved pulse modulator model. The simulation results are compared with the experimental data, showing the model validity. Based on the simulated model, a better matching between the wire-to-wire reactor load to the pulse generator may be achieved. [ABSTRACT FROM PUBLISHER]

An indoor two-wire transmission line (TL) was used to investigate the development of corona discharge during the propagation of a short HV pulse, for both polarities. The pulse voltage peak ranged from 40 to 100 kV with a pulse width of 5 ns at the full-width half-maximum points. The charge per unit length q was derived from the measurement of the voltage and current at the beginning of the TL. The q-v hysteresis curves were used to analyze the properties of the corona developed along the TL. It was found that at peak voltages much higher than the corona onset voltage, the q-v curves’ characteristics were similar to those found for μs surge pulses at overhead transmission lines. For peak voltages close to the corona onset, the corona exhibited charge neutralization oscillations and the charge buildup delay time vanished. It was also found that the positive corona is up to about six times more dissipative than the negative one, even though the negative corona onset voltage was somewhat lower than the positive, and q at the peak voltage is similar for both polarities. [ABSTRACT FROM AUTHOR]

An inductive-based power supply (240 μH, 50 kA) was used for the investigation of the foil explosion process in the time range of 0.05 ms

Thin film MIM-systems on the basis of amorphous silicon oxynitride (Si[sub x]N[sub y]O[sub z]) 40nm thick have been prepared. Being formed under superhigh electric field conditions (10[sup 9]Vm[sup -1]) the MIM-systems assume the ability to emit heated electrons in vacuum. The I-V characteristics of an emission current are subject to a law analogous to the Fowler-Nordheim equation. The system conductivity is determined by the insulator material only and at low temperatures the Poole-Frenkel mechanism is of the greatest significance. [ABSTRACT FROM AUTHOR]

Electromagnetic scattering in accelerating reference frames inspires a variety of phenomena, requiring employment of general relativity for their description. While the ‘quasi-stationary field’ analysis could be applied to slowly-accelerating bodies as a first-order approximation, the scattering problem remains fundamentally nonlinear in boundary conditions, giving rise to multiple frequency generation (micro-Doppler shifts). Here a frequency comb, generated by an axially rotating subwavelength (cm-range) wires is analyzed theoretically and observed experimentally by illuminating the system with a 2 GHz carrier wave. Highly accurate ‘lock in’ detection scheme enables factorization of the carrier and observation of multiple peaks in a comb. The Hallen integral equation is employed for deriving the currents induced on the scatterer and a set of coordinate transformations, connecting laboratory and rotating frames, is applied in order to make analytical predictions of the spectral positions and amplitudes of the frequency comb peaks. Numeric simulations of the theoretic framework reveal the dependence of the micro-Doppler peaks on the wire's length and its axis of rotation. Unique spectral signature of micro-Doppler shifts could enable resolving internal structures of scatterers and mapping their accelerations in space, which is valuable for a variety of applications spanning from targets identification to stellar radiometry. [ABSTRACT FROM AUTHOR]

This paper reports the ongoing effort on development of efficient, compact pulsed corona sources for pollution control applications. The system comprises an all-solid 4 kW average-power nanosecond pulser and a plasma reactor. The pulser is based on a single-stage magnetic compressor generating ~50 kV, 1-5 J and 50-100 ns pulses across a multi-wire reactor having an impedance of approximately 100 Ω, at pulse repetition frequency of up to 1 kHz. The principle of operation of the compressor is described. Equivalent circuits for two consecutive operation stages of the compressor accounting for nonlinear processes in magnetic switches are presented and analyzed. It was found that for the given topology, the optimal ratio of the primary and secondary capacitances is less than "classical" unity value that is characteristic for most magnetic compression systems. The freewheeling diode was constructed from UX-FOB diodes chosen on the basis of the comparison of forward losses of several fast recovery diodes at pulsed conditions. Electrostatic analysis of a complex reactor structure was reduced to a simple problem of coaxial electrodes. This allowed for the implementation of a simplified corona model integrated into a PSpice simulation. The simulated waveforms bear close resemblance to their experimental counterparts. It was found that the reactor breakdown voltage decreased considerably with the increase of the pulse repetition frequency. In several cases, the latter effect was clearly associated with ozone build-up. [ABSTRACT FROM AUTHOR]