Ignition Voltage Research Articles

Antenna induced hot restrike of a ceramic metal halide lamp recorded by high-speed photography

The hot restrike is one of the biggest challenges in operating ceramic metal halide lamps with mercury as buffer gas. Compared to a cold lamp, the pressure within a ceramic burner is two orders of magnitude higher during steady state operation due to the high temperature of the ceramic tube and the resulting high mercury vapour pressure. Room temperature conditions are achieved after 300 s of cooling down in a commercial burner, enclosed in an evacuated outer bulb. At the beginning of the cooling down, ignition voltage rises up to more than 14 kV. A significant reduction of the hot-restrike voltage can be achieved by using a so called active antenna. It is realized by a conductive sleeve surrounding the burner at the capillary of the upper electrode. The antenna is connected to the lower electrode of the lamp, so that its potential is extended to the vicinity of the upper electrode. An increased electric field in front of the upper electrode is induced, when an ignition pulse is applied to the lamp electrodes. A symmetrically shaped ignition pulse is applied with an amplitude, which is just sufficient to re-ignite the hot lamp. The re-ignition, 60 s after switching off the lamp, when the mercury pressure starts to be saturated, is recorded for both polarities of the ignition pulse with a high-speed camera, which records four pictures within the symmetrically shaped ignition pulse with exposure times of 100 ns and throws of 100 ns. The pictures show that the high electric field and its temporal variation establish a local dielectric barrier discharge in front of the upper electrode inside the burner, which covers the inner wall of the burner with a surface charge. It forms a starting point of streamers, which may induce the lamp ignition predominantly within the second half cycle of the ignition pulse. It is found out that an active antenna is more effective when the starting point of the surface streamer in front of the sleeve is a negative surface charge on the inner tube wall. The high-speed photos show that the ignition process is very similar in lamps with Hg or Xe as buffer gas.

Ignition characteristics of semiconductor bridge based on lead styphnate and lead azide charges under capacitor discharge conditions

Eight different sizes of semiconductor bridges and three kinds of charges, namely normal-lead styphnate (N-LS), lead azide (LA) and the double stacked charge (N-LS/LA), were selected to study the ignition characteristics of semiconductor bridge igniters under capacitor discharge conditions. The Neyer D-optimal Method was utilized in the experiments to explore the critical ignition voltages of the igniters. The relationships among the ignition voltage, current, resistance, and ignition time as well as other parameters of these igniters were analyzed. The results obtained were as follows: 1) The critical ignition voltage is positively proportional with the bridge area for the igniters possessing identical charge and ignition mechanism. 2) The ignition time and critical ignition voltage are related to the charges. The relationship of ignition time and charge following the short to long ranking is LA, N-LS/LA, and N-LS, but the relationship of critical ignition voltage and charge follows the opposite ranking. 3) The electroexploding ignition mechanism brings about shorter ignition time than electrothermal ignition mechanism for the igniters with identical charge, but the electroexploding ignition mechanism is accompanied by higher critical ignition voltage than the other.

Modeling of the effect of temperature and field-induced electron emission from the cathode with a thin insulating film on the Townsend discharge ignition voltage in argon–mercury mixture

A model of the low-current (Townsend) discharge in argon–mercury mixture in the presence of a thin insulating oxide film on the cathode is developed. It takes into account the cathode ion-electron emission and the electron emission from the cathode metal substrate under the strong electric field generated in the film by the ion surface charge. An influence of the mixture temperature and the oxide film on the discharge ignition voltage is estimated and it is shown that formation of a thin insulating film on the cathode surface can facilitate the discharge ignition in mercury-containing gas discharge devices at low temperatures.

Experimental Study of EDM-Drilling and Shaping of SiSiC and SiC

A growing interest in the machining of Silicon carbide (SiC) is caused by its excellent properties. This makes SiC and Siliconized Silicon carbide (SiSiC) suitable for a variety of applications, like cutting tools, electric systems, electric circuit elements, structural materials, etc. However, the material properties create difficulties in SiSiC processing. For this reason electrical discharge machining (EDM) was utilized to process it. The influence of EDM drilling process parameters such as pulse duration, polarity and ignition voltage on material removal rate (MRR), electrode wear, machining time and hole diameter are studied in the present work. All drilling and shaping experiments were performed using standard brass multi-hole electrodes with internal flushing. The highest impact to the material removal rate was reached with electrode negative polarity and ignition voltage of 120V. Experiments showed almost linear dependence between ignition voltage and MRR in the range from 60V to 120V. The highest reduction of the electrode wear was reached with positive electrode polarity and pulse duration of 5μs. Experiments showed a square law dependence between pulse duration and electrode wear in the range from 0.6μs to 5μs. This is due to the fact that the thermal conductivity and melting point of brass is lower than that of SiSiC. The material removal process can be caused by thermal stress and cracking as well as melting and evaporation. The increase of impulse frequency creates cracking and spalling effect that can be the reason why the short impulses bring higher material removal.

Changes in the Power Discharge in a Plasma Reactor Using Porous Versus Solid Dielectric Barriers and Meshes Electrodes

Many scientists are trying to increase the ozone production efficiency to improve the environment by increasing water and air quality. Important parameters, such as the dielectric constant, thickness, gap distance, and surface condition of an electrode, influence the efficiency of ozone production in a plasma reactor. This paper analyzed the results of experiments on the impact on the power generated in dielectric discharge that occur in a plasma reactor with mesh electrodes using two different dielectric materials. To carry out the experiment, a plasma reactor was constructed with the two mesh electrodes, the mesh having a $0.3\times 0.3$ mm2 diameter, and either a glass dielectric with a thickness of 1.1 mm or a porous dielectric in the form of silica gel beads. The results were analyzed by comparing the power generated by the porous dielectric body versus the glass dielectric. The analysis concluded that the use of a porous dielectric demonstrated power increases up to 3.5 times more obtained for the glass dielectric. It was also noted that the discharge ignition voltage $V_{i}$ and the supply voltage $V_{m}$ of the porous dielectric were almost the same value, and the difference $\Delta V = 11$ %, while for the glass dielectric, $\Delta V = 60$ %. There were also differences in discharge characteristics, dielectric barrier discharge on streamer resistance, between the two dielectric materials.

On temperature dependence of the parameters of corona discharge current–voltage characteristics

The dependences of the parameters of corona discharge current–voltage characteristics on the gas temperature are considered in this work. It is shown that the corona discharge ignition voltage U c (T) of helium and nitrogen decreases with the increase in temperature. The dependence of the parameter A(T) is complicated. It increases at the initial and final sections of the studied temperature range (20–369°C) and decreases at its central portion with two extrema. As the discharge in nitrogen is unstable, we failed to obtain any definite regularity. Generalized dependences that make assertions about the presence of a discharge different from a corona are presented. We made an assumption of an important role of two effects in the observed processes: the absorption of ions by the surface of electrodes and the continuous change in ion mobility due to the ion mass variation in the course of clustering and declustering of ions. It is supposed that there is a dynamic equilibrium between them in a steady state.

Ignition Characteristics of Micro‐Energy Semiconductor Bridges with Different Ignition Compositions

AbstractExperimental research was carried out under the stimulation of 10 μF tantalum capacitor discharge, to obtain the ignition characteristics of micro‐energy semiconductor bridges (SCB) with different ignition compositions. Meanwhile, the critical ignition voltages of different pyrotechnics were tested by the Neyer‐D optimal sensitivity test method. The results reveal that SCBs with multiple ignition compositions are entirely different in ignition voltage and current signal. These five kinds of pyrotechnics in ascending order of firing sensitivity are: refined lead styphnate, neutral lead styphnate, basic lead styphnate, zirconium/potassium chlorate, and lastly lead azide, while lead ferrocyanide/potassium perchlorate and boron/potassium nitrate are relatively insensitive to SCB.

The Effect of Tube Diameter on an Atmospheric‐Pressure Micro‐Plasma Jet

The micro‐plasma jet is a unique way of transporting active species of plasma to small targets for applications such as a single cancer cell treatment, and endoscopic surgeries. In this letter, the authors present numerical studies on a single cylindrical electrode micro‐plasma jet. The effect of tube diameter on sustaining voltage, electron density, and the density of reactive species are investigated. The diameter of the dielectric tube was varied in the range between 0.1 and 1mm. A pulsed direct current voltage with rising phase of 50 ns was used to ignite the plasma jet. The sustaining voltage monotonically increased with the decreasing diameter of the tube. More electrons wall losses happened due to the faster drift movement to the inner wall of smaller tube diameter, therefore, the decreasing pre‐avalanche electron density need increasing ignition voltage to facilitate the avalanche‐streamer transition as the tube diameter decreased. The increasing ignition voltage increased the chemical reactivity of plasma jet. The peak density of O2* and O increased more than 20 times as the tube diameter decreased from 1 to 0.1 mm.

Breakdown mechanism in hydrogen microdischarges from direct-current to 13.56 MHz

This paper contains the results of experimental studies of the breakdown phenomena in hydrogen microdischarges from direct current to very high radio frequencies. Measurements were performed for two types of electrode configurations, glass melting electrodes and electrodes with Bruce profiles, by varying the gap size from to , with the pressure ranging between and . The breakdown voltage curves and waveforms of the discharge voltage and current are presented and discussed. In the low-frequency region, the breakdown voltage values are comparable to the dc breakdown voltage data. The breakdown voltages recorded for high frequencies are similar to and lower than those obtained for the low-frequency region. For the gap size of , the breakdown voltage does not depend on the frequency since the strong electric field formed in microgaps overcomes the electron work function, enhancing secondary-electron production. The current-generating mechanism before breakdown is field emission, as verified by a linear Fowler–Nordheim plot with a negative slope. With increasing gap size, the breakdown voltage increases since the contribution of the field emission is progressively reduced. The breakdown voltages that correspond to the glass melting electrodes are lower since such electrodes have edge issues and an inability to achieve a homogeneous field, unlike electrodes with Bruce profiles. The results presented here could be useful both for a better understanding of the non-equilibrium processes which occur in radio-frequency microdischarges during breakdown and for determining the minimum ignition voltages in microplasma sources as well as the maximum safe operating voltage and critical dimensions in other microdevices.

A quantitative optimisation model for a horizontal MEMS solid propellant thruster with experimental verification

This paper studies the effect of multiple geometric parameters of a micronozzle on a MEMS solid propellant thruster (MSPT) and establishes a quantitative optimisation model. Influences of the structural parameters of the micronozzle on performance are accurately calculated. The significance and contribution ratio of each parameter are evaluated by F distribution. Correspondingly, a horizontal MSPT is fabricated and tested to prove the optimisation model. In the implementation, a complete microigniter is formed by a single layer of Au, achieving an ultra-low ignition voltage of 2.1 V with an extremely low ignition resistance of 4 Ω.

Post Disaster Illumination for Underground Mines

Lighting systems provide mine workers improved visibility and contribute to improved safety, productivity, and morale. Lighting is critical to miners, since they depend heavily on visual cues to spot fall of ground, pinning & striking and slipping & tripping hazards. Most conventional systems of lighting are used in mines are extracting a lots of power and deal with major maintenance problems. Apart from the conventional grid-power lighting systems, additional emergency lighting system using green energy is mandatory in case of grid-power failure or in disaster situation of the underground mines. The luminous efficacy increases with switching frequency while providing eye comfort to user. Even though CFL has low power consumption for solar photovoltaic (SPV) power system, but CFL’s electrical requirements are not easily met by hard-switched inverters due to their higher switching losses at higher frequencies and preheat and ignition voltage of CFL results lower efficiency. This paper demands well suited high frequency inverter and a series interrupting type charge controller for illumination at remote areas. DOI: http://dx.doi.org/10.11591/telkomnika.v13i3.7069

원거리 공진 기동시 과전압 방지 HID 안정기

The electronic ballast for HID lamps needs to ignite lamps even though the length from the ballast to lamp is far away. Therefore, it needs to do the research on a resonant ignition to turn on the HID lamps because the reduction of ignition voltage is not much depending on the distance. However, the parasitic capacitance is increased depending the length of the cable, and it affects the resonant frequency. The ignitor voltage can be increased drastically under the resonant ignition through frequency sweep, and it is the main reason of blowing up. Therefore, the clamping diode is proposed to suppress the voltage of the primary winding during resonant ignition.

Surface Plasmas Versus Volume Plasma: Energy Deposition and Ozone Generation in Air and Oxygen

The energy deposition and the ozone generation in a shielded sliding discharge were compared with those of a simple surface discharge and a pulsed corona discharge in atmospheric pressure air and oxygen. All discharges were generated by applying 160 ns, high voltage pulses. Under the same conditions, the highest energy deposition per pulse was obtained with the shielded sliding discharge. The energy deposition was lower by a factor of four for the surface discharge plasma and by an order of magnitude for the pulsed corona discharge plasma. Replacing air with the more electronegative oxygen caused a decrease in the deposited energy due to electron attachment. The threshold voltage for plasma formation in oxygen in a shielded sliding discharge was approximately 5 kV, three times less than that of the surface discharge (≥15 kV) and four times less than that of the pulsed corona discharge (≥20 kV). A new finding of this study is that, whereas the decrease in energy in the pulsed corona discharge was ≥50 %, and that of the simple surface discharge ≥40 %, it was negligible in the shielded sliding discharge. Since the ozone generation scales with energy density, the results show that plasma reactors based on the nanosecond sliding discharge principle have major advantages in compactness, ignition voltage, and in the use of oxygen, rather than air, compared to surface discharges and corona discharges.

Temporal characteristics of the pulsed electric discharges in small gaps filled with hydrocarbon oil

In order to understand the role of electrode materials in electrical discharges with micro gaps (<200 µm) filled with a liquid hydrocarbon dielectric, the post-breakdown phase of low ignition voltage (100 V) and low current (<20 A) pulsed electric discharges is experimentally investigated. The electric discharge energies are selected in the range from 1 to 150 mJ. Due to the non-repetitive and transient nature of the micro-discharges, time-resolved imaging, spectroscopy and electrical analysis of single discharges are performed. The plasma–material interaction is investigated by analysing the erosion craters on anode and cathode. It is found that the electrode materials in these multiphase discharges affect the gas bubble dynamics, the transport properties of the discharge plasmas and the transition from the gaseous to metallic vapour plasma. The change in the energy fractions dissipated in the electrodes in function of the discharge time is influenced by the thermo-physical properties of the electrode materials. The simulation of craters in multiple discharge process requires consideration of the gas bubble dynamics due to different energy fractions and plasma flushing efficiencies.

An atmospheric-pressure, high-aspect-ratio, cold micro-plasma.

An atmospheric pressure nonequilibrium Ar micro-plasma generated inside a micro-tube with plasma radius of 3 μm and length of 2.7 cm is reported. The electron density of the plasma plume estimated from the broadening of the Ar emission line reaches as high as 3 × 1016 cm−3. The electron temperature obtained from CR model is 1.5 ev while the gas temperature of the plasma estimated from the N2 rotational spectrum is close to room temperature. The sheath thickness of the plasma could be close to the radius of the plasma. The ignition voltages of the plasma increase one order when the radius of the dielectric tube is decreased from 1 mm to 3 μm.

Investigating antennas as ignition aid for automotive HID lamps

This paper considers the ignition of mercury-free high-intensity discharge (HID) lamps for car headlights. Due to safety reasons, these lamps need to have a fast run-up phase which is ensured, amongst other things, by a high Xe pressure of roughly 15 bar (cold) in the discharge vessel. The high Xe pressure causes an increased ignition voltage compared with former mercury-containing automotive HID lamps or low-pressure lamps used for general-lighting applications.The increase in ignition voltage can be limited if the electric field in front of the electrodes is raised by an uplifting of the electrical conductivity along the outer wall of the inner bulb either by a conductive layer on its surface or by a dielectric barrier discharge (DBD) within the outer bulb. This paper considers on the one hand conventional antennas deposited by physical vapour deposition (PVD) and on the other hand a combination of these antennas with a DBD within the outer-bulb operated in 100 mbar Ar as ignition aids. In both cases the antenna potential and antenna width are varied. Additionally, the effects of antenna thickness and antenna material are investigated.The ignition voltage, ignition current and light emission during ignition are measured on a nanosecond timescale. Furthermore, for the very first time, the ignition process is recorded in four consecutive intensified charge-coupled device images using a high-speed camera system with a time resolution in the range of nanoseconds.It was found that antennas strongly reduce the ignition voltage of automotive HID lamps. Active antennas reduce the ignition voltage significantly more than passive antennas, proportional to the conductance of the antenna. Combining conventional antennas with an outer-bulb discharge reduces the ignition voltage from 19 kV without any ignition aid to the intrinsic ignition voltage of the lamp below 10 kV, in the best case.

Transition of Electron Field Emission to Normal Glow Discharge

The field emission (FE) properties of single walled carbon nanotube (SWCNT)/graphene hybrid samples were investigated for high currents in dc mode and pulsed mode with pulse-ON times between 0.2 and 400 ms and duty cycles between 1% and 80% with stainless steel anodes. Our dc measurements showed a transition to glow discharge (GD) already at currents larger than 10 mA. The pulsed \(I\) – \(V\) characteristics with up to 400-mA maximum current were limited by the cathode resistance, consisting of the emitting layer resistance and the contact resistance, which was found to be between 1.1 and 1.4 \(\text{k}{\Omega }\) . A constant-voltage behavior arises after subtracting the cathode resistance. This constant-voltage behavior, the observed glowing during FE, and time-resolved measurements give evidence for the transition of Fowler–Nordheim-type FE to FE enhanced GD. FE enables a soft transition to normal GD without the need of an ignition voltage. The buildup dynamic and the time constants of the transition to GD were evaluated and discussed. The FE and GD behaviors were also compared using copper and molybdenum anodes.

Performance Evaluation of Pulse Compressor-Based Modulators With Very Fast Rise Times for Plasma Channel Drilling

In this paper, limitations of a compact and durable solid state modulator, using a 4.5kV IGBT in combination with a pulse compression circuit are evaluated. The investigated modulator utilizes two separate paths-one for ignition voltage and one for high currents. The ignition voltage is generated with a pulse compression circuit based on saturable transformers, which is used to charge a series capacitor. After saturation, the capacitor is connected to the output. Parasitics have been estimated in order to find an optimized modulator configuration. Measurement results for validating the models as well as the simulation performance are presented. Main limitation factors are described and possible solutions discussed.

Controlled structures in laterally patterned barrier discharges by illumination of the semiconductor electrode

In this contribution, we present a possibility to actively control emerging patterns in laterally extended barrier discharges. One of the barriers is a high-ohmic semiconductive GaAs electrode. As the electrode is illuminated from its plasma-far side, the voltage inside the plasma gap is increased. If the gap voltage becomes higher than the ignition voltage of the gas, a discharge is started. A corresponding electrical model is given. The lateral resolution of control for a laterally homogeneous discharge is investigated. It is found that the luminescence of the discharge is controlled by both a variation of illumination power density and a variation of the applied voltage. However, during an increase in the applied voltage, the discharge may become larger than the area of illumination. Further, an investigation of the patterned discharge control shows that the number of current spots depends on the illumination power density and the area of illumination. The behaviour of current spot appearance suggests an inhibitory influence, preventing a discharge in its immediate surrounding and limiting the total number of current spots.

Glow discharge based device for solving mazes

A glow discharge based device for solving mazes has been designed and tested. The device consists of a gas discharge chamber and maze-transformer of radial-azimuth type. It allows changing of the maze pattern in a short period of time (within several minutes). The device has been tested with low pressure air. Once switched on, a glow discharge has been shown to find the shortest way through the maze from the very first attempt, even if there is a section with potential barrier for electrons on the way. It has been found that ionization waves (striations) can be excited in the maze along the length of the plasma channel. The dependancy of discharge voltage on the length of the optimal path through the maze has been measured. A reduction in discharge voltage with one or two potential barriers present has been found and explained. The dependency of the magnitude of discharge ignition voltage on the length of the optimal path through the maze has been measured. The reduction of the ignition voltage with the presence of one or two potential barriers has been observed and explained.