High-voltage Generator Circuit Research Articles

Research on Triode Based High Re-Frequency Ultrafast Electrical Pulse Generation Technology

The high-repeat frequency ultrafast electrical pulse generation technology is mainly based on ultrafast switching devices combined with ultrafast circuits to generate electrical pulses with repetition frequencies of several kilohertz and a rise-time of nanoseconds or even picoseconds. This technology is the basis for several research studies and is one of the key technologies that has received wide attention from various countries. The problems to be solved are high re-frequency ultrafast high-voltage pulse generation and ultra-broadband ultrafast pulse transport and circuit stability applicability, which include circuit conduction mechanism research, pulse generation time improvement and recovery time reduction. By studying the avalanche transistor high-voltage transient conduction characteristics and reducing the loss in the carrier transport process, the influence of each parameter on the output is determined, and the key factors to enhance the circuit performance are identified. This paper designs a new high-repetition frequency ultrafast electric pulse generation (UPG) circuit using pure electronics components, which consists of combining avalanche transistor model 2N2222 with a hybrid Marx structure at the same time in the pulse circuit to add filtering, fast recovery diodes and pulse cutoff and other matching techniques to make its output more stable, which can obtain higher output frequency, faster rise-time and narrower pulse widths. It has been tested that a high re-frequency ultrafast high-voltage electrical pulse signal with a pulse repetition frequency of 200 kHz, a leading edge of 800 ps, a half-high pulse width of 5 ns, an amplitude of 1.2 kV and jitter of less than 5% can be generated at the load with a 50 Ω load at the output. The signal can be applied in the fields of ultrafast diagnosis, information countermeasures and nuclear electromagnetic radiation research.

Radiation Measurement with Data Acquisition Using LabVIEW

Radiation monitoring and measurement are important for radiation safety. Such monitoring and measurement must be carried out in order to investigate workplace conditions and individual exposures, to ensure that radiological conditions in the workplace are acceptable, safe, and satisfactory, and to keep records of radiation monitoring over a long period of time in accordance with regulations or as good practice. However, radiation monitoring instruments and system are expensive. A cost-effective radiation monitoring system using Geiger Muller (GM) radiation detector was developed. A high voltage generation circuit and data acquisition were implemented using LabVIEW software. The cost-effective radiation monitoring system is easy to use, and it can detect radiation, analyzed and record the data in a personal computer. This newly developed system is simple and can provide the radiation dose data for further analysis. An experiment was conducted to compare and calibrate the collected data at the Secondary Standard Dosimetry Laboratory (SSDL). The result shows that the new developed GM detector provides good correlation between counts per minute (cpm) and dosage units, which is good characteristic of a radiation counting system

Comparative study of the design and simulation of an AC to high DC voltage generation circuit

Decades after the invention of the Cockcroft–Walton voltage multiplier, it is still being used in broad range of high voltage and ac to dc applications. High voltage ratio and high efficiency are its main features. Due to the limitations of original circuit, reducing the output ripple and increasing the accessible voltage level motivated scientists to propose new topologies. However, over the worldwide bibliography, most of Cockcroft-Walton voltage designers persist in using equal capacitances in every stage without considering an optimal design. The aim of this paper is to do a comparative study of the design and simulation of a fixed model (conventional model used by most authors) and a variable model (new design) of generating High Voltage Direct Current (HVDC) based on Cockcroft–Walton voltage multiplier that stresses on the choice of the adequate capacitance values to reduce the output voltage drop, produce less ripple and the calculations of the optimal number of stages that is necessary to produce the desired output voltage with a better performance. The generation of HVDC based on Cockcroft–Walton voltage multiplier and an eight stage was used for simulations and theoretical analysis which yielded up to 4.4 kV DC from an input voltage of 230 V, 50 Hz ac supply. The results are compiled from the simulations done on MATLAB/SIMULINK, by the designs and simulations characteristics of the models the performances, output voltages and ripple voltages per stage have been compared.

ПРИМЕНЕНИЕ ТАСИТРОНОВ В СХЕМАХ С ИНДУКТИВНЫМ НАКОПИТЕЛЕМ ЭНЕРГИИ

Features of generating high voltage in a pulsed or weakly pulsating form for different applications with an inductive energy storage device are considered. High voltage (tens of kilovolts) is generated due to self-induction when the storage is disconnected using a high-voltage tacitron-type switch device from a low-voltage pumping current source (with voltage less than 1 kV). The tacitron is a gas-discharge triode with a dense control grid, which provides initiation of a discharge between the cathode and anode and pumping the storage at a positive voltage, and then disconnecting it from the pumping current source, when a negative voltage of 20-200 V is applied to the grid for the blocking of the electron flow to the anode. Tacitrons are able to turn-off currents from a few to hundreds of amperes in the presence of a high voltage between the cathode and anode that takes a time of the order of 1 μs. Diagrams of changes in time of the current and voltage of the tacitron and the load during the generation of both pulsed and weakly pulsating voltages are considered. In the latter case, an additional storage (filter) capacitor is connected in parallel with the load, supplying the load by energy during the pumping periods of the inductive storage, and a high-speed pulse gas-filled rectifier diode is proposed to use for the dynamic separation of the storage capacitor and tacitron circuits in the said periods. Formulas are given that allow one to evaluate the parameters of the high voltage generation process. It is proposed to use a combined switching device containing tacitron and pulse gas-filled diode in one envelope with a common cathode electrode to simplify the high voltage generator circuit.

Study of gas discharge thyratron-type interrupter with sector hole in the screen in high-voltage pulse generator circuit with inductive energy storage

The work presents experimental study results of gas discharge interrupter with a sector hole in the screen and a circular grid hole being asymmetrically placed regarding central axis as part of a high-voltage pulse generator with inductive energy storage. According to the results received the device under consideration managed to decrease minimum turn-off time by 6 times up to 30 ns compared to a switch with inverse hole pattern in a grid node. Limiting pulse voltage amplitude is fixed at the level of 50 kV, peak pulse power increase up to 13 MW is achieved.

Operation mode of the proton injector in the linac of the Institute for Nuclear Research with a 100-Hz pulse repetition rate

Results of the analysis and upgrading of the high-voltage pulse generator circuit in the proton injector for operation with a 100-Hz pulse repetition rate are presented.

방사선 측정장치의 저준위 방사선 측정과 방사선량의 급격한 변화에 따른 장치의 반응 속도개선에 관한 연구

This paper suggests an algorithm to measure low-level radiation by radiation measuring devices, and the other algorithm to improve reaction speed of the device to better respond to dramatic changes in radiation amount. The former algorithm to improve the accuracy of measuring low-level radiation takes advantage of a dual window radiation measurement method which is based on accumulated average of pulses gathered by a radiation measuring sensor. The latter algorithm is to enhance reaction speed of a measuring device to more sensitively react to dramatic changes in radiation amount by adopting a dual window radiation measurement method which analyzes data patterns newly put into for six seconds. To verify the suggested algorithms, a hardware-which consists of sensor and high-voltage generator, controller, charger and power supply circuit, wireless communication part, and display part-was used. Tests conducted on the dual window radiation measurement method as used in the suggested algorithm have proved that accuracy improves to measure low-level radiation of 5uSv/h, and linearity also gets better. Other tests were conducted to see whether the suggested algorithm enhances the reaction speed of a radiation measuring device so that the device responds better to dramatically changing radiation amount. The experimental results have shown meaningful changes in numbers after six seconds. Therefore, the conclusions are made that the algorithm enhances the reaction speed of the device.

Evaluating Generator Circuit Breakers Short-Circuit Duty Using IEEE C37.010 and C37.013

This paper describes a procedure for calculating generator circuit breaker duty. Currently, commercially available software products help in determining the duty for a general-purpose circuit breaker. However, further calculations are needed to determine the duty for a special-purpose generator circuit breaker. IEEE Std C37.010-1999 provides the calculation procedure for general-purpose circuit breakers. In order to evaluate a special-purpose generator circuit breaker, this paper will expand the steps and methodology used in IEEE C37.010-1999 by presenting a procedure and detailed calculations for finding a duty multiplication factor based on the test X/R ratio of generator circuit breakers given in IEEE C37.013-1997 (Standard for AC High-Voltage Generator Circuit Breakers Rated on a Symmetrical Current Basis). This way, engineers can still make a generator circuit breaker assessment although generator circuit breaker evaluation module is not included in many commercial short-circuit programs.

Monitoring of HV Generator Circuit Breaker Contact Ablation Based on Acoustic Emission

High-voltage (HV) generator circuit breaker (GCB) is a key protective element for isolating HV generators in case of faults, or operational reasons. GCB typically has a double contact system. During the breaking operation process of the GCB, at first the nominal contact opens; after a while, the arcing contact opens with a minimum time-elapse between the two operations. An arc ignites when the arcing contact opens. This arc should concern the arcing contact only because the nominal contact is not designed to withstand arcs. However, after each operation the arcing contact is slightly ablated because of the arc. The ablation due to arcing makes the contact shorter and shorter. Therefore, the time interval between the two opening operations also gets shorter. For proper operation of the GCB, a minimum time interval for the commutation of the current from the nominal contact system to the ablation contact system has to be assured. In this paper, a noninvasive direct ablation measurement method based on acoustic emission is presented. This is aimed at monitoring the delay in the time instant of the start of arcing contact touch as it gets shorter due to ablation, from the acoustic emission signals. Test results carried out on real breakers substantiate the proposed approach.

Detailed Analysis of the Transient Voltage in a JT-60SA PF Coil Circuit

A superconducting coil system is actually complicated by the distributed parameters, e.g. the distributed mutual inductance among turns and the distributed capacitance between adjacent conductors. In this paper, such a complicated system was modeled with a reasonably simplified circuit network with lumped parameters. Then, a detailed circuit analysis was conducted to evaluate the possible voltage transient in the coil circuit. As a result, an appropriate (minimum) snubber capacitance for the Switching Network Unit, which is a fast high voltage generation circuit in JT-60SA, was obtained.

Influence of dc Component during Inadvertent Operation of the High Voltage Generator Circuit Breaker during Mis-Synchronization

This paper analyses the synchronization problem of a generator onto power system without satisfying synchronization condition. The main focus of the paper is on the impact of the dc component of the current in the high voltage circuit breaker during its close-open operating cycle. Using real time measurements of currents/voltages and angles during the close-opening cycle of high voltage generator circuit breaker and the impact of the dc component of current in context of interrupting large magnitude of current from the circuit breaker. In addition, the paper describes a study case model and the results of simulations performed using the software EMTP-ATP of an actual incident that occurred during the inadvertent synchronization of a large 339 MW, 24 kV generator to the grid.

High voltage generator circuit with low power and high efficiency applied in EEPROM

This paper presents a low power and high efficiency high voltage generator circuit embedded in electrically erasable programmable read-only memory (EEPROM). The low power is minimized by a capacitance divider circuit and a regulator circuit using the controlling clock switch technique. The high efficiency is dependent on the zero threshold voltage (Vth) MOSFET and the charge transfer switch (CTS) charge pump. The proposed high voltage generator circuit has been implemented in a 0.35 μm EEPROM CMOS process. Measured results show that the proposed high voltage generator circuit has a low power consumption of about 150.48 μW and a higher pumping efficiency (83.3%) than previously reported circuits. This high voltage generator circuit can also be widely used in low-power flash devices due to its high efficiency and low power dissipation.

Integrated circuit-based instrumentation for microchip capillary electrophoresis

Although electrophoresis with laser-induced fluorescence (LIF) detection has tremendous potential in lab on chip-based point-of-care disease diagnostics, the wider use of microchip electrophoresis has been limited by the size and cost of the instrumentation. To address this challenge, the authors designed an integrated circuit (IC, i.e. a microelectronic chip, with total silicon area of <0.25 cm2, less than 5 mmx5 mm, and power consumption of 28 mW), which, with a minimal additional infrastructure, can perform microchip electrophoresis with LIF detection. The present work enables extremely compact and inexpensive portable systems consisting of one or more complementary metal-oxide-semiconductor (CMOS) chips and several other low-cost components. There are, to the authors' knowledge, no other reports of a CMOS-based LIF capillary electrophoresis instrument (i.e. high voltage generation, switching, control and interface circuit combined with LIF detection). This instrument is powered and controlled using a universal serial bus (USB) interface to a laptop computer. The authors demonstrate this IC in various configurations and can readily analyse the DNA produced by a standard medical diagnostic protocol (end-labelled polymerase chain reaction (PCR) product) with a limit of detection of approximately 1 ng/microl (approximately 1 ng of total DNA). The authors believe that this approach may ultimately enable lab-on-a-chip-based electrophoretic instruments that cost on the order of several dollars.

20208 モノタンク式X線発生装置における高効率放熱構造(熱工学(2))

An effective cooling structure is applied to an insulation-oil-filled mono-tank 260 Watts X-ray generator which incorporates a high voltage generation circuit and an X-ray tube. The proposition are achieving effective heat radiation along with protecting the high voltage generation circuit including high-voltage transformer, semi-conductor diodes and capacitors by thermally separating from the heat produced from the X-ray tube radiator. The thermal separator plays a crucial role of avoiding heat diffusion and keeping the high temperature of the space around the radiator effectively leading to heavy heat flows toward a cooling fin adjacent to the fervent space. In this paper, the cooling model for a mono-tank type X-ray generator and the experimental results are shown and discussed where the proposed method is suggested to be highly effective.

DESIGN OF MODIFIED FOUR-PHASE CMOS CHARGE PUMPS FOR LOW-VOLTAGE FLASH MEMORIES

A new four-phase clock scheme for the four-phase charge pumping circuits using standard 0.5 μm CMOS technology at low supply voltages to generated high boosted voltages is proposed. Boosted clocks without high drivability are applied on the capacitors coupled to the gates of the main charge transfer transistors to compensate body effects. Thus, the high-voltage clock generation circuit can be easily achieved for clock frequency of 10 MHz. Due to the nearly ideal pumping gain per stage, the design methodology to optimize power efficiency is also presented. With the new clock scheme, it can efficiently pump to 9 V at supply voltage of 1 V using 10 stages by simulations, while pump to 4.7 V at supply voltage of 1.5 V using four stages by measurements.

A plasma initiator using a multi-winding transformer for large tokamak devices and the application to the poloidal field coil power supply system.

This paper describes a multi-winding transformer as a plasma initiator in tokamak devices and the application to the design of poloidal field coil power supply system. The scale of tokamak device has been considerably increased based on some experimentally obtained scalings of a energy confinement, because the plasma performance has been improved with the current and size parameters. Since large tokamaks require the hybrid functional poloidal field coil system, the each coil power supplies must prepare the high voltage generation circuit for the plasma breakdown, and it causes increase in the number of current interrupters, disconnectors and the resisters. Therefore, the plasma position and shape control tend to be difficult especially in the start-up phase of the discharge. The plasma initiator proposed in this paper makes the plasma initiation circuit to be simple by unification of the high voltage generation circuit. It has similar ampere-turn and permeance distribution with the tokamak device and produces the magnetic field necessary for plasma breakdown. An application to FER tokamak proposed by JAERI is also presented.

Eine impulsstrahlungsquelle für ein megavolt summenladespannung in gedrängter bauweise: I. Der Stoβspannungsgenerator

After a short description of the principle of a high-voltage impulse generator circuit a report is given about the construction of an impulse generator with a total charging voltage of 1 MV and an impulse energy of 5 kWs. Because of the use of new capacitors it is possible to build the circuit with a very small volume. Therefore we get a specific energy volume from only 2.42 kWs/m 3. The impulse generator circuit is the principal part of the pulsed particle accelerator.