A high-voltage pulse generator for electric-discharge technologies

The electric circuit and design of a high-volta ge pulse generator with an output voltage of ≥3 50 kV is described. The generator operates in the nanosecond range of pulse durations (~300 ns) at a repetition rate of up to 10 pulses/s in a continuous mode and is intended for electric-discharge technologies. The energy stored in the generator is ~600 J, and the energy released in a pulse is ≥300 J. A discharge of a capacitive storage through a toroidal pulsed transformer and a discharge gap is used in the generator.     

A low-impedance high-voltage bipolar pulse former

The results on the formation of bipolar pulses with amplitudes of up to 100 kV, a duration of 2 ns, and a pulse repetition rate of 100 Hz across a 12.5-Ω load are presented. Lines with a characteristic impedance of 6.25 Ω were switched using multichannel ring switches with 70-mm-diameter electrodes in a nitrogen medium at a pressure of 40–60 atm. At a pressure of 40 atm, the rms deviation of the operation time of the sharpening switch reaches 40 ps at a voltage-pulse rise rate of 7 × 10¹³ V/s at the electrodes. As the pressure increases, the stability of the output bipolar pulses deteriorates; this is probably associated with a disturbance of the multichannel-switching mode in the sharpening switch. The performed simulation of the pulse-former operation showed that the energy loss in the switches reaches 40% of the stored energy in the output line of the Sinus-160 generator.     

A thermoacoustic sensor for recording high-power nanosecond microwave pulses

The operating principle and design of an uncooled noise-immune high-power microwave pulse sensor is described. The sensor operation is based on the effect of acoustic signal generation when microwave pulses are absorbed in a layer structure, in which a thin metal nanometer-thick film is used as an absorber. The sensor is placed in a free space and intended to detect microwave pulses with ～10- to 100-ns durations in a 10- to 300-GHz frequency band with a pulse repetition rate of up to 5 kHz. For 10-ns-long pulses, the sensor sensitivity is 0.5 V/mJ.     

A high-power pulse amplifier for radar and navigation systems

A high-power pulse amplifier intended for pulse excitation of microwave generators on 3A750, 3A762, 3A765, and 3A766 diodes is described. An advantage of the amplifier is that its output voltage is independent of the load resistance owing to a low output resistance of ～0.05 Ω. The performance characteristics of the amplifier are as follows: a maximal output voltage of 120 V, a maximal output pulse current of 25 A, a pulse rise time of 10 ns, amplified-pulse durations of 20 to 300 ns, and a gain of 35 dB.     

A pulse microwave generator

The tunable generator intended for producing rectangular microwave pulses with a 1-μs duration, 50-Hz pulse repetition rate, and 1-kW power, operating in a frequency range of 2.7–3.7 GHz, is described. The generator can be used for calibrating microwave detectors and tuning microwave units in investigations performed in the area of relativistic microwave electronics.     

A low-frequency high-power arbitrary-shape voltage pulse generator

A circuit diagram and design of the arbitrary-shape bipolar voltage pulse generator with amplitudes up to 800 V and a peak output on a matched load of 400 kW are described. The generator is based on car rechargeable batteries and power insulated-gate bipolar transistors (IGBTs). Results of the experiments aimed at producing high-power harmonic signals with frequencies of 50 Hz and 1 kHz are presented.     

Small switches of high-power microsecond pulses on the basis of high-voltage integrated pulse thyristors and reverse switch-on dynistors

A high-voltage switch on the basis of a small unit of series-connected high-voltage integrated pulse thyristors (HVIPTs), which were developed at the Ioffe Physical Technical Institute, was designed and investigated. At a power voltage of 25 kV, current pulses of microsecond duration with an amplitude of 2.8 kA and a rise time of 0.8 μs were switched. The attained current density through an HVIPT (5.6 kA/cm²) appreciably exceeds the permissible current density for conventional thyristors. It is shown that the developed HVIPT unit can be used in the triggering circuit of a high-power assembly of reverse switch-on dynistors (RSDs) at an operating voltage of 25 kV, which consists of 14 series-connected dynistors with a diameter of their structures of 24 mm. The RSD switch with a triggering circuit on the basis of HVIPTs allowed switching of rapidly rising current pulses with an amplitude of 20 kA and a duration of 150 μs. The small dimensions of the HVIPT unit (4 × 10 × 32 cm) and the RSD assembly (7 × 7 × 34 cm) determine the wide prospects for using them in high-power pulse technology.     

A high-voltage pulse transformer with a modular ferrite core

A high ratio (winding ratio of 1:80) pulse transformer with a modular ferrite core was developed for a repetitive resonant charging system. The magnetic core is constructed from 68 small blocks of ferrites, glued together by epoxy resin. This allows a high degree of freedom in choosing core shape and size. Critical issues related to this modular design are the size tolerance of the individual ferrite blocks, the unavoidable air gap between the blocks, and the saturation of the core. To evaluate the swing of the flux density inside the core during the charging process, an equivalent circuit model was introduced. It was found that when a transformer is used in a resonant charging circuit, the minimal required volume of the magnetic material to keep the core unsaturated depends on the coupling coefficient of the transformer and is independent of the number of turns of the primary winding. Along the flux path, 17 small air gaps are present due to the inevitable joints between the ferrite blocks. The total air gap distance is about 0.67 mm. The primary and secondary windings have 16 turns and 1280 turns, respectively, and the actually obtained ratio is about 1:75.4. A coupling coefficient of 99.6% was obtained. Experimental results are in good agreement with the model, and the modular ferrite core works well. Using this transformer, the high-voltage capacitors can be charged up to more than 70 kV from a low-voltage capacitor with an initial charging voltage of about 965 V. With 26.9 J energy transfer, the increased flux density inside the core was about 0.23 T, and the core remains unsaturated. The energy transfer efficiency from the primary to the secondary was around 92%.     

400-kV trigatrons for high-power low-inductance pulse generators

A series of four-channel trigatrons operating at a voltage of up to 400 kV and a current of 280 kA per channel have been developed and tested. The control electrode is coaxially arranged in a hole of the main (positive) high-voltage electrode. This design ensures a small spread (jitter) of the operation delay time (Δt _d < 1 ns) for the discharge gap filled with elegas (SF₆). The electric strength of lateral surfaces of the device body is increased without using dielectric fluids. The service life of switches is increased by using tubular metal (steel) screens in the working volume. For the parallel operation of trigatrons, the Δt _d value is also below 1 ns, but it sharply increases if the gap between the main electrodes exceeds 11–12 mm.     

A high-power nanosecond pulse generator based on solid-state switches

A high-power nanosecond pulse generator based on a Lewis transformer and ultrafast IGBT-transistors is described. The generator ensures the formation of square pulses at a 50-Ω matched load with a repetition rate of up to 2 kHz. The pulse duration may be freely varied from 20 to 200 ns, and the pulse power may vary from 200 W to 2 MW.     

高压方波不可逆电穿孔肿瘤消融装置的研制

根据高压脉冲引起细胞不可逆电穿孔而使组织消融的机理,应用现代电子电力技术、高电压技术及嵌入式技术,研制了一套可实现输出脉冲频率、脉宽和峰值参数独立可调的高压方波脉冲肿瘤消融装置.装置研制完成后,在实验室连接电阻负载调试,调试结果表明,装置运行稳定,输出的方波脉冲波形符合不可逆电穿孔研究需要,达到了装置的预期设计目标,同时也为将来针对离体细胞和小动物的不可逆电穿孔实验打下基础.     

200 ns pulse high-voltage supply for terahertz field emission

We present a method of generating 200 ns high-voltage (up to 40 kV) pulses operating at repetition rates of up to 100 kHz, which may be synchronized with laser pulses. These supplies are simple to make and were developed for ultrafast terahertz pulse generation from GaAs photoconductive antennas using a high-repetition-rate regeneratively amplified laser. We also show an improvement in signal-to-noise ratio over a continuous dc bias field and application of the supply to terahertz pulse generation.     

A compact subnanosecond high-voltage bipolar pulse generator with spark gaps

Two modifications of the compact subnanosecond high-voltage bipolar pulse generator with an active unit based on a high-impedance charging line, forming line, and two uncontrolled nitrogen spark gaps without gas purging are studied. In both cases, the forming lines are charged with compression of the energies of incident pulses with a ∼160-kV amplitude, a ∼4-ns duration, and a ∼1.5-ns leading edge. The difference of operation modes of the circuits and their efficiency are specified by a point of connecting the load. In conditions of nanosecond prebreakdown overvoltage at a 100-Hz repetition rate, the spark gaps were energized with a relative scatter of ±(100–170) ps, thus specifying the stability of the shape of output bipolar pulses with a voltage difference up to 250 kV.     

A high-voltage nanosecond pulse generator based on a barrier discharge

One of the specific features of the barrier electric discharge is the short duration of microdischarge processes that last about tens of nanoseconds. A high-voltage nanosecond pulse generator based on a barrier electric discharge is presented. A voltage of tens of kilovolts is usually applied to electrodes of the discharge cell. The peak values of the current pulse may be very high (from a few amperes to several tens of amperes). The presented high-voltage nanosecond pulse generator, having a sufficiently simple design, ensures quite good pulse repetition stability, and, when necessary, allows one to easily tune characteristics of pulses and their repetition rates by changing the geometrical, electrical, and physical-chemical parameters of the setup.     

Development of high-voltage pulse-slicer unit with variable pulse duration for pulse radiolysis system

A high-voltage pulse-slicer unit with variable pulse duration has been developed and integrated with a 7 MeV linear electron accelerator (LINAC) for pulse radiolysis investigation. The pulse-slicer unit provides switching voltage from 1 kV to 10 kV with rise time better than 5 ns. Two MOSFET based 10 kV switches were configured in differential mode to get variable duration pulses. The high-voltage pulse has been applied to the deflecting plates of the LINAC for slicing of electron beam of 2 μs duration. The duration of the electron beam has been varied from 30 ns to 2 μs with the optimized pulse amplitude of 7 kV to get corresponding radiation doses from 6 Gy to 167 Gy.     

A compact repetitive high-voltage nanosecond pulse generator for the application of gas discharge

Uniform and stable discharge plasma requires very short duration pulses with fast rise times. A repetitive high-voltage nanosecond pulse generator for the application of gas discharge is presented in this paper. It is constructed with all solid-state components. Two-stage magnetic compression is used to generate a short duration pulse. Unlike in some reported studies, common commercial fast recovery diodes instead of a semiconductor opening switch (SOS) are used in our experiment that plays the role of SOS. The SOS-like effects of four different kinds of diodes are studied experimentally to optimize the output performance. It is found that the output pulse voltage is higher with a shorter reverse recovery time, and the rise time of pulse becomes faster when the falling time of reverse recovery current is shorter. The SOS-like effect of the diodes can be adjusted by changing the external circuit parameters. Through optimization the pulse generator can provide a pulsed voltage of 40 kV with a 40 ns duration, 10 ns rise time, and pulse repetition frequency of up to 5 kHz. Diffuse plasma can be formed in air at standard atmospheric pressure using the developed pulse generator. With a light weight and small packaging the pulse generator is suitable for gas discharge application.     

A high-voltage nanosecond pulse generator for exciting diffuse gas discharges at atmospheric pressure

A high-voltage nanosecond pulse generator intended for studying diffuse discharges in gases at pressures close or equal to atmospheric pressure is described. The generator produces pulses with an ∼50-ns (at half-height) duration, a >50-kV voltage amplitude, a 10- to 12-ns rise time, and a pulse repetition rate of up to 1 kHz across an equivalent load (1.3 kΩ, 15 pF). The generator is based on available cheap components, and the amplitude (energy) of output pulses and their repetition rate can be promptly regulated in a wide range. The generator is immune to noise and reliable.     

Reversible, high-voltage square-wave pulse generator for triggering spark gaps

A design is presented for a reversible, square-pulse generator that employs coaxial cables for charge storage and pulse formation and a thyratron as the switch. The generator has a nominal output voltage of 5-30 kV and a pulse duration determined by the cable's physical length. Two variations are presented: (1) a single-stage one consisting of cable that is charged via its shield on one end and discharged with a thyratron on the opposite end and (2) a two-stage one having an inverting circuit that uses a coaxial cable to reverse the polarity of the pulse. The generator operates with "flying shields," i.e., high-voltage pulses also propagate on the outside of the cables; this calls for a dedicated insulation that avoids breakdown between sections of the cable's shield. The rise time obtained is mostly dictated by the switching time of the thyratron; with the one we used in the tests, rise times in the range of 30-40 ns were obtained. We present the results obtained in the implementation of the generators as well as its application to fire a large Marx generator.     

A high-power semiconductor switch of high-voltage pulses with a rise time of nanosecond duration

The results of studies of new fast-acting semiconductor devices—deep-level dynistors intended for use in high-power devices of nano-and microsecond pulsed-power technology—are presented. The possibility of switching multikiloampere current pulses having a rise rate of 200 kA/μs with the use of a single device with a 12-mm-diameter structure is shown. A high-power switch based on an assembly of dynistors with an operating voltage of 12 kV connected in series is described. The switch is capable of switching current pulses with a 1200-A amplitude and a 4-ns rise time.     

辐照用加速器调制器的设计

本文介绍了用于辐照加速器的速调管脉冲调制器的部分主要部件的理论计算,依据理论计算得出了调制器部分主要部件的参数.并简要介绍了用于辐照加速器的脉冲调制器的系统概况、性能和技术指标.