Nitric oxide (NO) is increasingly being used in medical applications. Currently, a gas cylinder of N_{2} mixed with a high concentration of NO is used in the NO inhalation system. However, this arrangement is potentially risky due to the possibility of accidental leak of NO from the cylinder. The presence of NO in air leads to the formation of nitric dioxide (NO_{2}), which is toxic to the lungs. Therefore, an on-site generation of NO would be very desirable for patients with acute respiratory distress syndrome and other related illnesses. Previously, our group reported the production of NO using a pulsed arc discharge. In this work, the prototype of the on-site NO generator was developed and the performances of the NO generator were demonstrated for medical applications.
The influence of the electric field distribution between the electrodes and the seed electron generation rate on the scattering of the breakdown voltage of SF_{6}-insulated spark gaps was investigated. The breakdown voltage scattering considerably can be reduced by applying large-gap-volume, uniform-field electrode profiles instead of spherical shaped electrodes. Moreover, uniform field electrode profiles exhibit an uniform discharge probability in the entire gap volume and following an almost uniform erosion of electrode material along the electrode's surface. This preserves electrode shape and switching performance of the spark gap for a long maintenance-free lifetime. Breakdown voltage scattering further can be reduced by increasing the seed electron generation in the gap by an auxiliary corona discharge adjacent to the main gap. The experimental observations are discussed on the basis of the volume time law for discharge initiation.
The process of synthesis of carbon deposits from hydrocarbon vapours in low-current electrical-discharge plasma was investigated in the paper. The carbon deposits were effectively synthesised in discharge of positive polarity generated between a stainless steel needle and a plate made of nickel alloy, for the discharge current ranged from 0.1 mA up to 3 mA. The experiments were carried out at normal pressure in cyclohexane vapours with argon as carrier gas. The process of synthesis of carbon deposits was investigated using optical emission spectroscopy.
A solution of the long-lasting problem with anomalous population statistics of pre-streamer avalanches has been proposed in the form of a new generalized probability density function.
In this paper an evaluation of a number of different insulating materials, under pulse breakdown conditions, is described. The experimental setup used an 8 stage Marx generator in order to generate a high potential difference (in the range 80-220 kV) between two spherical electrodes which were spaced 1.5-3.5 mm apart. The breakdown voltage of each of the materials was recorded and the data was then post-processed in order to determine the breakdown strength of each of the samples.
We investigate the pulsed flashover voltage of dielectric samples at up to 4 bar SF_{6} in the simultaneous presence of a high current (>10 kA, ∼20 microsecond pulse) volume discharge nearby. The chosen distance, ∼7 cm, between surface and volume breakdown is consistent with conditions found in the Sandia-Z-machine type rimfire switch. For a flashover gap distance of 24 mm and a simultaneous excitation within ∼ 5 microseconds, we observe an average reduction in the flashover voltage from 164 kV to 142 kV at 3.7 bar when the volume discharge is turned on. The test setup utilizing a magnetic switching scheme operating at 320 kV and 10 kA is briefly discussed along with the breakdown properties and the spectral characterization of the volume/surface flashover discharge plasma. In general, UV light propagates relatively unattenuated for wavelengths >160 nm in the high pressure SF_{6} from the volume discharge to the dielectric surface, setting up conditions which are conducive to photoelectron emission from the dielectric.
An investigation was made of the characteristics of the formation of a selfcontroled volume discharge for the pumping of CO2 lasers, i.e. self-sustained volume discharge (SSVD), which involved a preliminary filling of a discharge gap by an electron flux from an auxiliary-discharge plasma. We have found that this method was suitable for large interelectrode gaps, that distortion of the electric field in the gap by the space charge of the electron flux played an important role in the formation of the discharge and that the electrodes could be profiled dynamically during propagation of an electron flux through the discharge gap and a SSVD could form in systems with a strongly inhomogeneous field. High power SSVD based CO2 laser systems have been created and investigated. Another type of self-controled volume discharge without pre-ionization, i.e. a selfinitiated volume discharge (SIVD), in nonchain HF lasers with SF6−C2H6 mixtures was investigated as well in our review. We have established that, after the primary local electrical breakdown of the discharge gap, the SIVD spreads along the gap in directions perpendicular to that of the electric field by means of the successive formation of overlapping diffuse channels under a discharge voltage close to its quasi-steady state value. It is shown that, as new channels appear, the current flowing through the channels formed earlier decreases. The volume occupied by the SIVD increases with increase in the energy deposited in the plasma and, when the discharge volume is confined by a dielectric surface, the discharge voltage increases simultaneously with increase in the current. The possible mechanisms which explain the observed phenomena, namely the dissociation of SF6 molecules and electron attachment SF6 molecules, are examined. A simple analytical model, which makes it possible to describe these mechanisms at a qualitative level, was developed. High power SIVD based HF(DF) lasers have been developed and tested.
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