High Voltage DC Power Supply Research Articles

WiFi-controlled portable atomic force microscope.

This article proposes to develop a WiFi-controlled portable atomic force microscope (AFM). The AFM consists of a horizontal probe, controlling circuits, digital to analog (D/A) and analog to digital (A/D) interfaces, a microcomputer (Raspberry Pi, RPi), and a laptop. The proposed AFM uses a pocket-size power supply to drive the controlling circuits, the D/A and A/D interfaces, as well as the RPi that constructs network hotspots and generates scanning signals. With special design and integration of the whole system, both of the AFM probe and electronic controlling system are portable. At a distance of 50 m from the proposed AFM, experiments in the constant height mode and the constant force mode are conducted to evaluate its performance. The results show that this WiFi-controlled AFM has a maximum scan range of 3.6 × 3.6 μm2 with nanometer order resolution. Meanwhile, it achieves satisfactory image contrast, stability, and repeatability. Compared with conventional AFMs, the AFM proposed in this paper no longer relies on commercial AC mains supply or high-voltage DC power supply, and realizes WiFi-controlled AFM scanning and imaging in 50 m or farther without wire or network cable connection to a laptop or a desktop computer. Given credits to these features, WiFi-controlled AFMs are expected to own a wider range of application, especially in isolated environments, outdoor researches, or even fieldwork investigations.

High voltage electrical system of 8.56 GHz CW klystron for electron cyclotron heating on QUEST spherical tokamak

A high voltage DC power supply for the cathode of the 8.56 GHz CW klystron has been set up for electron cyclotron heating (ECH) in steady state tokamak operation on QUEST spherical tokamak. The power supply is equipped with an IGBT array and a reactor for fast shutoff of the voltage in 10 μs, where the influx of electric energy at the short circuit is limited to 5 J. AC switches also have been installed in the three-phase power lines. High voltage relays are useful to save electric energy consumption. Fast three-phase AC switching by IGBT-stack is applicable to reduce the electric load of the components of the klystron power supply.

Characterization and effect of atmospheric corona plasma on grey knit polyester fabric

The use of chemical compounds in dyeing is still dominant. This results in the redundant use of water for the washing. Therefore, there needs to be a research on an alternative method. This research is aimed at understanding the effect of both positive and negative corona plasma irradiations on fabric. It is expected that characteristics of voltage, current, and electrode spacing, as well as ion mobility from the corona plasma will be known, both for with and without grey polyester knit fabric. Other than that, dampness characteristics of the grey polyester knit fabric will also be known. Plasma discharge is generated using point-plane electrode configuration connected to a high voltage DC power supply. The number of point electrodes is 100. Meanwhile, irradiation on the fabric is performed by putting the grey polyester knit on top of the plane electrode. Characterization was then carried out by varying the voltage, spacing of both point and plane electrodes, with and without the fabric. Other than that, variation was also made for the duration of grey polyester knit fabric irradiation. The next step was water drop test to observe 1 mL water absorption on the grey polyester knit. Results show that adding potential difference increases the current of corona spark plasma discharge for both positive and negative current corona discharges. The same case was also observed when the plasma discharge was irradiated on the plane electrode, either with or without the grey polyester knit fabric. The presence of grey polyester knit altered discharge mobility in that the small spacing of the fabric increases mobility for both negative and positive corona discharge. Hence, the further the electrodes spacing, the less mobile charge particles become. Results of water drop test show that longer irradiation on the fabric speeds up water absorption in the grey polyester knit fabric, both for positive and negative corona irradiations.

A Reopened Crowbar Protection for Increasing the Resiliency of the Vacuum Tube High-Voltage DC Power Supply Against the Vacuum Arc

High-voltage power supplies (HVPSs) are widely used to supply vacuum tubes. The amount of delivered energy from the HVPS to the tube is an important issue during the vacuum arc in the tube. The conventional protection mechanism consists of a shunt crowbar which diverts the fault current from the tube to itself as a parallel path. The crowbar circuit is usually built of the devices without the turn-off capability. It is a drawback since the output of the power supply is shortened for a long time. Thus, the restoration time of these power supplies is excessive. This demerit can have detrimental effects on mission-critical applications. In this paper, the insulated-gate bipolar transistor (IGBT)-based crowbar structure is studied to overcome this issue. In the proposed protection mechanism, the crowbar can be reopened intentionally after closing. A theoretical analysis is presented to compare power supply performance in the presence of the conventional crowbar with the IGBT-based crowbar. The experimental results are presented to demonstrate the practical considerations of the proposed crowbar structure and its appropriate performance. This paper shows that HVPS has more fault resiliency and less restoration time with the proposed IGBT-based crowbar.

작은 출력전압 불균형을 가지는 LCC 공진형 컨버터 기반의 고전압 DC 전원장치 개발

작은 출력전압 불균형을 가지는 LCC 공진형 컨버터 기반의 고전압 DC 전원장치 개발

Note: Isolated high-voltage thermo-compensated DC power supply for mass spectrometry.

The design of a highly stable isolated high voltage power supply is proposed and developed. The power supply is characterized by good temperature stability (<15 ppm/°C) and very low ripple level (<7 ppm) which were reduced by using a sinusoidal voltage in the transformer conversion. We anticipate that the power supplies of this type can find their utility in modern high-resolution mass spectrometers, particularly in time-of-flight and Orbitrap-type instruments providing a high resolution of ∼100 000 FWHM and high accuracy of m/z determination.

Design and simulation of series resonant push-pull 3KV DC high voltage power supply

In order to meet high efficiency and small size of neutron tube ion source power supply, a technical solution of series resonant push-pull converter is proposed. This converter utilizes the parasitic parameters of mosfet to eliminate oscillation of the circuit, and uses the first capacitor of capacitor-doide voltage multipliers as resonant component to achieve ZVCS of the switch to reduce loss. First Harmonic Approximation is used to establish voltage gain mathematical model to reflect the influence of quality factor on voltage gain. Parameter design method for push-pull LC resonant voltage multipliers is given. A prototype was simulated by saber software to verify the correctness of theoretical analysis.

Feasibility study on medical isotope production using a compact neutron generator

Compact neutron generators can provide high flux of neutrons with energies ranging from thermal (0.025 eV) to 14 MeV. Recent measurements demonstrated high neutron yields from the D–7Li fusion reaction at an interaction energy of 500 keV. Using the D−7Li reaction and applying new advancements in high flux neutron generator technology along with the commercial availability of high voltage DC power supplies enables the production of useful quantities of radioisotopes for medical applications. Using the known neutron reaction cross-sections, it has been estimated that hundreds-to-thousands MBq (or tens-to-hundreds mCi) of 99Mo, 225Ac, 64Cu and 67Cu can be obtained from a compact high flux neutron generator.

The establishment and simulation of bidirectional Cockcroft-Walton circuit model

PurposeThe purpose of this paper is to improve the stability of high voltage DC power supply and reduce the ripple.Design/methodology/approachThe study was conducted using the simulation analysis model and numerical calculation.FindingsBy increasing the output arm capacitance, the expression of ripple and times of the output arm capacitance and the auxiliary arm capacitance is derived. The output ripple is determined by the value of the output arm capacitance. Finally, the correctness of the method and the formula are verified using circuit simulation.Originality valueThis paper presents a method to improve the power supply stability.

Energetic metallic ion implantation in polymers via cost-effective laser-driven ion source

This research work reports the ions emission from the plasma generated by Nd:YAG laser having wavelength 1.064 μm, power 1.1 MW, pulse energy 10 mJ and intensity 1011 W/cm2 irradiated at 70° with respect to the target normal to the ions. These ions were accelerated through a home-made extraction assembly by means of a high voltage DC power supply. The energy of these ions were measured using Thomson parabola technique which utilizes Solid State Nuclear Track Detector (CR-39) and confirmed by Faraday cup as well that exploits a well-known technique known as time of flight. Interestingly, a significant increase in energy (from 490 to 730 keV) was observed with a discrete increase in acceleration potential from 0 to 18 kV. Polyethylene terephthalate (PET) and polypropylene were exposed to this recently developed ion source facility, to authenticate the reliability of this facility. The surface of the polymer is affected when energy of the irradiated ion is increased, which is evident from the optical micrographs. An increase in electrical conductivity was also observed with the increase in ion energy.

The Establishment and Analysis of Bidirectional Cockcroft-Walton Circuit Model

High voltage DC power supply is very important in laser and high precision instruments, so the stability of high voltage DC power supply has an affect on the stability of laser and equipment. The voltage doubling rectifier circuit is the core component of the high voltage generator, so it is very important to study the stability of the voltage doubling rectifier circuit. Through the study of bidirectional rectifier circuit, double voltage rectifier circuit produces an output ripple and response time is superior than the basic voltage rectifier circuit. At the same time to study the bidirectional rectifier circuit is optimized, the capacity of the output arm greatly increases which leads to reduction in the output ripple, as the capacity reaches large enough value the output ripple approaches zero. Thus, greatly increasing the circuit in steady state time.

Review on High Voltage DC Power Supply for Pulsed Power Supply Application

Review on High Voltage DC Power Supply for Pulsed Power Supply Application

Performance of novel high throughput multi electrospray systems for forming of polymeric micro/nanoparticles

In order to maintain a stable cone-jet mode in electrospray low flow rates are used while most applications require a high throughput. We compare two different designs of the multiple electrospray system in order to increase the output for large scale production applications. In this study, the solution was fed through four separate needles that were attached to either a circular or a rectangular metallic plate that were connected to a high voltage DC power supply. The behaviour of the electrospray jets as well as the deposition of particles were investigated. It was shown that the throughput of particles was increased while particles with narrow size distribution were produced from all four uniform electrospray jets.

Long-pulse power-supply system for EAST neutral-beam injectors

The long-pulse power-supply system equipped for the 4 MW beam-power ion source is comprised of three units at ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences): one for the neutral-beam test stand and two for the EAST neutral-beam injectors (NBI-1 and NBI-2, respectively). Each power supply system consists of two low voltage and high current DC power supplies for plasma generation of the ion source, and two high voltage and high current DC power supplies for the accelerator grid system. The operation range of the NB power supply is about 80 percent of the design value, which is the safe and stable operation range. At the neutral-beam test stand, a hydrogen ion beam with a beam pulse of 150 s, beam power of 1.5 MW and beam energy of 50 keV was achieved during the long-pulse testing experiments. The result shows that the power-supply system meets the requirements of the EAST-NBIs fully and lays a basis for achieving plasma heating.

Investigation of mechanisms in plasma-assisted ignition of dispersed coal particle streams

The plasma-assisted ignition enhancement of pulverized lignite particles is intensively studied in a laminar, upward Hencken flat-flame burner. By applying a pair of pin-to-pin electrodes with a high-voltage DC power supply, the apparent reductions of ignition delay time, about 0.8–3.5ms, are observed for all three ambient temperatures, 1200K, 1500Kand 1800K, across which the ignition mode transits from heterogeneous ignition (HI) to hetero-homogeneous combined one. Concentrated on 1200Kambience where HI mode prevails, the plasmas-induced reduction of ignition delay time as a function of the applied voltage (0–20kV) is explored, in which the chemical effect is found to play a key role in cases with voltage less than 3kV. Then, under the conditions of different oxygen mole fractions, the discharge mechanisms and the reductions of ignition delay time are further examined to distinguish the chemical and thermal effects on the ignition enhancement. Finally, the gas temperature rise, both measured and predicted at a point located 6mmabove the electrodes, verifies the thermal effect. This paper provides a preliminary understanding of plasma-assisted ignition mechanisms on dispersed coal particles that may be applied in practical combustion system.

Modular Multilevel Converter-Based Bipolar High-Voltage Pulse Generator With Sensorless Capacitor Voltage Balancing Technique

In order to generate bipolar high-voltage (HV) pulses across certain load from HV dc (HVdc) power supply, a voltage source inverter (VSI) stage should be inserted between the load and the supply. In order to meet the required HV level, series connection of semiconductor devices should be employed with dynamic voltage sharing between the involved devices. Modular multilevel converter (MMC) can be used instead of the conventional two-level VSI to alleviate the complexity introduced by the deployment of series-connected devices. The voltage level of the HVdc power supply and the voltage rating of the available semiconductor devices determine the suitable number of MMC voltage levels ( $N$ ). Capacitor voltage balancing is a vital issue for proper operation of the MMC. In general, conventional sensor-based balancing techniques require a significant amount of measurements, which increases the complexity of the system. In addition, the high dv/dt during switching times causes electromagnetic interference, which may adversely affect the accuracy of the measurements. In this paper, a sensorless voltage balancing technique is proposed for the MMC-based bipolar HV pulse generator that reduces the system sensitivity, cost, and complexity. A detailed illustration of the proposed approach is presented in this paper. The simulation and experimental results are used to validate the proposed concept.

Metode Elektrooptis sebagai Pendeteksi Radikal Bebas dan Prospek untuk Evaluasi Total Mutu Minyak Goreng

&lt;span&gt;One main problem of standard methods for determination of frying oil quality is various &lt;span&gt;parameter of indicators with their various wide of methods or equipments. In this research we &lt;span&gt;proposed a new method for determination of oil quality using single electrooptics parameter to &lt;span&gt;replace previous indicators. The samples used in the experiment were various conditions of &lt;span&gt;palm oils from the same brand. The level of oil quality was proposed by the value of &lt;span&gt;2&lt;span&gt;, which &lt;span&gt;represents as the relative number of free radicals produced in the sample. The change of &lt;span&gt;polarization was measured by the value of as the samples were induced by an external &lt;span&gt;electric field using high voltage dc power supply. At room temperature of 28 C electrooptics &lt;span&gt;method seems capable to detect free radicals and to distinguish all kinds of palm oils. This &lt;span&gt;method has an opportunity to provide a single parameter of oil quality and an evaluator of &lt;span&gt;halal or authentic food from fats.&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;br /&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;

Lateral coalescence of bubbles in the presence of a DC electric field

In this work, the influence of electrohydrodynamic forces on lateral bubble coalescence during nucleate pool boiling is investigated. An experimental pool boiling test facility was used with n-pentane as the working fluid. Boiling took place atop a polished copper surface on which two artificial nucleation sites were fabricated. The nucleation sites were 180μm in diameter and 500μm deep with a centre-to-centre spacing of 660μm. Two diametrically opposed windows allowed for illumination and high speed videography of the bubble growth process from the two nucleation sites. For the saturated boiling tests considered here, bubbles only formed at the two artificial nucleation sites allowing their coalescence behaviour to be scrutinized. A screen electrode above the boiling surface and a high voltage DC power supply facilitated the establishment of the electric field which was varied between 0 and 34.5kVcm−1. Observation of the high speed videos has revealed that bubble coalescence is influenced in such a way that it is delayed in the presence of the electric field to such an extent that, at the highest electric field strength tested, it is avoided all together. To help explain the observed results, a simple numerical model is solved showing that bubbles in close proximity to one another create an electric field distribution with high intensity between them. The overall result is net polarization forces that push the bubbles apart, and the closer they are together the larger this repulsive force becomes.

Four-electrode micropump with peristaltic motion

We present an electrostatically driven four-electrode micropump that operates with peristaltic motion. The working fluid is gas. In particular, we focus on the characteristics of the micropump as a function of the various actuating signals for four flexible electrodes. The micropump operated between 60V and 120V with a customized pulse signal. Whereas the maximum flow rate using a basic actuating signal was approximately 38μl/min at 90V and 15Hz, the maximum flow rate using an optimized actuating signal was approximately 136μl/min at 90V and 15Hz. This is an increase of approximately 3.6 times the minimum flow rate. Various actuating signals were generated from a microcontroller unit (MCU) equipped with a logic circuit and a high-voltage DC power supply and function generator. The minimum flow rate occurs with a four pumping sequence with three electrodes. However, the maximum flow rate occurs when these four electrodes participate sequentially. The proposed micropump consists of only a single chamber and a flexible membrane with four electrodes. The chamber is divided into smaller cells with the embedded electrodes controlled by a custom-made logic circuit that generates various phase-sequencing actuation signals. This micropump is applicable for gas chromatography.

Investigating Pulsed Discharge Polarity Employing Solid-state Pulsed Power Electronics

The power electronics technique has become a key technology in solid-state pulsed power supplies. Since pulsed power applications have been matured and found their way into many industrial applications, moving toward energy efficiency is gaining much more interest. Therefore, finding an optimum operation condition plays an important role in maintaining the desired performance. Investigating the system parameters contributed to the generated pulses is an effective way in improving the system performance further ahead. One of these parameters is discharge polarity, which has received less attention. In this article, the effects of applied voltage polarity on plasma discharge have been investigated in different mediums at atmospheric pressure. The experiments have been conducted based on a high-voltage DC power supply and a high-voltage pulse generator for point-to-point and point-to-plane geometries. Furthermore, the influence of electric field distribution is analyzed using finite-element simulations for the employed geometries and mediums. The experimental and simulation results have verified the important role of the applied voltage polarity, employed geometry, and medium of the system on plasma generation.