High-voltage Plate Research Articles

Design and realization of a nearby lightning-electric field environment simulator

Objectives Lightning can be extremely harmful to ships on the open seas. Especially with the large-scale application of electronic and electrical equipment and closed integrated masts, the lightning indirect effect on ships is becoming increasingly serious. In order to effectively carry out the lightning indirect effect test for shipborne electrical and electronic equipment, Methods a kind of nearby lightning-electric field environment simulator based on the principle of Marx generator was designed and realized in this paper. The simulator realized the peak cut-off of the impact high voltage by using the adjustable single chopping sphere gap, and established a simulated nearby lightning-electric field environment through the high voltage plate and the conductive ground plane. Results The test results show that the device has a cut-off time of less than 2 μs and a drop time of less than 0.09 μs, which can produce a pulsed electric field environment that meets the requirements of GJB 1389A-2005. Conclusions This paper can provide equipment support for the research on the indirect effect of the nearby lightning strokes on system electronic and electrical equipment based on GJB 8848-2016.

Plasma Wake Simulation for Charged Space Platforms: Fully Kinetic PIC Versus Hybrid PIC

A comparative study using both electrostatic hybrid particle-in-cell (PIC) and fully kinetic PIC simulations is carried out to study collisionless, mesothermal plasma flow over large, negatively charged plates. The surface potential considered covers plasma wakes under the “quasi-neutral,” the thin sheath, and the “thick sheath” regimes. It is shown that both approaches produce qualitatively similar plasma wake features. The hybrid-PIC approach is accurate in the sheath region around the plate and in the expansion fan region. The full-PIC simulations also confirm the presence of the embedded sheath in the wake generated by a charged plate. However, the hybrid-PIC model is quantitatively inaccurate in the deep wake region where the electrons are nonequilibrium. It is also found that, for high-voltage plates, the ratio of the ram side ion current collection to the backside one scales linearly with the logarithm of the surface potential.

Design of the free-air ionization chamber, FAC-IR-150, for X-ray dosimetry

The primary standard for X-ray dosimetry is based on the free-air ionization chamber (FAC). Therefore, the Atomic Energy Organization of Iran (AEOI) designed the free-air ionization chamber, FAC-IR-150, for low and medium energy X-ray dosimetry. The purpose of this work is the study of the free-air ionization chamber characteristics and the design of the FAC-IR-150. The FAC-IR-150 dosimeter has two parallel plates, a high voltage plate and a collector plate. A guard electrode surrounds the collector and is separated by an air gap. A group of guard strips is used between up and down electrodes to produce a uniform electric field in all the ion chamber volume. This design involves introducing the correction factors and determining the exact dimensions of the ionization chamber by using Monte Carlo simulation.

A 10(9) neutrons/pulse transportable pulsed D-D neutron source based on flexible head plasma focus unit.

A 17 kJ transportable plasma focus (PF) device with flexible transmission lines is developed and is characterized. Six custom made capacitors are used for the capacitor bank (CB). The common high voltage plate of the CB is fixed to a centrally triggered spark gap switch. The output of the switch is coupled to the PF head through forty-eight 5 m long RG213 cables. The CB has a quarter time-period of 4 μs and an estimated current of 506 kA is delivered to the PF device at 17 kJ (60 μF, 24 kV) energy. The average neutron yield measured using silver activation detector in the radial direction is (7.1 ± 1.4) × 10(8) neutrons/shot over 4π sr at 5 mbar optimum D2 pressure. The average neutron yield is more in the axial direction with an anisotropy factor of 1.33 ± 0.18. The average neutron energies estimated in the axial as well as in the radial directions are (2.90 ± 0.20) MeV and (2.58 ± 0.20) MeV, respectively. The flexibility of the PF head makes it useful for many applications where the source orientation and the location are important factors. The influence of electromagnetic interferences from the CB as well as from the spark gap on applications area can be avoided by putting a suitable barrier between the bank and the PF head.

New techniques to evaluate the incendivity of insulators

New techniques for evaluating the incendiary behavior of insulators is presented. The onset of incendive brush discharges in air is evaluated using standard spark probe techniques for the case simulating approaches of an electrically grounded sphere to a charged insulator in the presence of a flammable atmosphere. However, this standard technique is unsuitable for the case of brush discharges that may occur during the charging–separation process for two insulator materials. We present experimental techniques to evaluate this hazard in the presence of a flammable atmosphere which is ideally suited to measure the incendiary nature of micro-discharges upon separation, a measurement never before performed. Other measurement techniques unique to this study include: surface potential measurements of insulators before, during and after contact and separation, as well as methods to verify fieldmeter calibrations using a charge insulator surface opposed to standard high voltage plates.

Development of a position sensitive neutron detector with high efficiency and energy resolution for use at high-flux beam sources

We are developing a high-efficiency neutron detector with 1 cm position resolution and coarse energy resolution for use at high-flux neutron source facilities currently proposed or under construction. The detector concept integrates a segmented 3He ionization chamber with the position sensitive, charged particle collection methods of a MicroMegas detector. Neutron absorption on the helium produces protons and tritons that ionize the fill gas. The charge is amplified in the field region around a wire mesh and subsequently detected in current mode by wire strips mounted on a substrate. One module consisting of a high-voltage plate, a field-shaping high-voltage plate, a grid and wire strips defines a detection region. For 100 % efficiency, detector modules are consecutively placed along the beam axis. Analysis over several regions with alternating wire strip orientation provides a two-dimensional beam profile. By using 3He, a 1/v absorption gas, each axial region captures neutrons of a different energy range, providing an energy-sensitive detection scheme especially useful at continuous beam sources.

Generation of nano-sized free standing single crystal silicon particles

A system has been designed to generate monodisperse, single crystal silicon nanoparticles. The particles are generated using a SiH4/H2 mixture in a high density plasma. An aerodynamic lens assembly focuses and size selects the particles. A high voltage plate is used to accelerate the charged particles such that they can be injected into a high temperature annealing tube to be heated. The shape and structure of the particles are changed in the annealing tube. Single crystals are obtained.

An electrostatic beam rocking system on the Surrey nuclear microprobe

The use of two sets of magnetic dipoles, producing opposite fields, to rock a focused MeV ion beam over the surface of a crystalline sample is now well established in several nuclear microprobe laboratories. Such a `beam rocking' system allows ion channeling analysis from micron-size regions of the sample to be measured, with a beam displacement over the sample surface as small as a few microns, and no requirements for an automated goniometer. While magnetic beam rocking systems are ideal for many applications, they are limited in the speed at which the beam can be rocked in angle owing to hysteresis effects. This may also cause problems of non-reproducibility of the beam displacement on a micron scale. Also, heavier ions are more difficult to rock through a given angle using a magnetic beam rocking system, whereas an electrostatic beam rocking system gives a rocking angle which is independent of the ion mass. This paper describes the construction and uses of a fast electrostatic beam rocking system, which uses two sets of high voltage plates driven in opposition at high frequencies. Ion optics simulations are used to model the performance of the system. The optics of this beam rocking system, in which both sets of deflection plates are located before the quadruplet lens formation are discussed. The uses of this system to rapidly image the location of crystal planes and axes, and to carry out rapid channeling analysis are presented.

Ionospheric plasma flow over large high-voltage space platforms. II: The formation and structure of plasma wake

Theory and particle simulation results are presented for ionospheric plasma flow over large high-voltage space platforms at a large angle of attack. Both the transient formation of the space-charge wake and its steady-state structure are studied. The wake-side ion impact and current collection are obtained. It is found that the wake behind a high-voltage plate is characterized by two ion-rich sheaths embedded in a quasineutral background wake. The embedded sheath is formed by the ions passing through the sheath around the plate edge and serves as their trajectory path. Depending on the surface potential, the plate dimension, and the angle of attack, the embedded sheath may either extend downstream or curve back to form a ‘‘hook’’ structure. As a result, the plate’s wake-side surface may receive a high, localized ion flux at the location the embedded sheath strikes.

Use of pulse-type x-ray analyzers to determine the level and profile of the stock in a blast furnace

The Leningrad Scientific-Industrial Association Burevestnik collaborated with the Chermetavtomatika Scientific-Industrial Association and the TsNIIchermet to develop a pulse-type x-ray analyzer to determine the level and profile of the stockline in a blast furnace for purposes of monitoring and optimizing the control of the smelting process. The analyzer is called ''TAIR'' and is based on the transit-time method of measurement. It includes a scanning x-ray generator, transducer, detector, data analysis and display block, and scanning control block. The generator consists of an x-ray tube, a modulator, and a high-voltage plate power source for the tube. The analyzer made it possible to adjust the instruments on the furnace during operation. Besides the stockline profile, the analyzer can be used to determine the thickness of the layer of the charge and the rate of descent of the charge. It can also produce the characteristics of the gas in the furnace above the stock.

Double parallel-plate electrostatic analyzer for Tara end-loss studies

An endloss spectrograph has been designed and is being fabricated for the Tara tandem mirror. This spectrograph is a double parallel-plate electrostatic analyzer about 60 cm in length with a 30° entrance angle; the high-voltage plate is a transparent wire cloth grid which allows higher energy particles to pass through for detection on a symmetric ground plane. The analyzer has three detection planes: first, the normal focal plane for low-energy detection at high resolution (0.1–4 keV); second, the entrance grounded plate for mid energies (4–6 keV); and third, the symmetric ground plane for coarse resolution at higher energies (8–20 keV). The analyzer is defocusing on the symmetric plane. This spectrograph will be able to measure simultaneously the endloss potential cutoff and ions from the neutral beams; in conjunction with a loss cone neutral beam source the resolution is sufficient (60 eV) to measure the plasma potential.

Variation avec la densité d'ionisation de la brillance des étincelles le long d'une trace de particule dans une chambre à étincelles

During experimentation with a lead-plate spark chamber built for the detection of primary cosmic electrons, the brightness of a single particle track slowing down in the lead plates is observed to vary with the ionization density of this particle. This effect is visible only if all the highvoltage plates are fed from the same condenser. The possibility of recording simultaneous tracks of particles of very different ionization density with a good efficiency is closely related to precision in gap length and other discharge conditions.

A cathode-ray oscillograph for the direct measurement of high-voltage transients

The paper describes a high-speed continuously-evacuated cathode-ray oscillograph for the recording of high-voltage transients; the distinctive feature of the instrument is that impulsive voltages of 100 kV to earth may be applied directly to either deflection plate singly, or +100 kV to one and − 100 kV simultaneously to the other, without the use of a potential divider. The reasons for. and advantages accruing from, the use of such an oscillograph are discussed, with particular reference to the distortion inherent in the use of potential dividers. Precautions to be observed in the operation of the high-voltage plates are described, reference being made to the means of producing the high vacuum required in the tube.A circuit producing a delayed high-voltage impulse is shown, and the possibilities of the instrument are demonstrated by a brief investigation of the characteristics of a sphere-gap when sparking over on the front of a steep-fronted wave.