Blumlein Pulse-forming Network Research Articles

Research on the influence of gas ionization on pulse forming in linear transformer driver (LTD) electron beam generator

Currently, there is limited research on the influence of gas ionization on the pulse formation process in pulse power source-driven loads. This paper introduces a road-field-Particle-In-Cell (PIC)/Monte Carlo Collision (MCC) collaborative simulation method that can accurately simulate gas ionization in Linear Transformer Driver (LTD) electron beam generation (EBG). The method couples the electromagnetic field and charged particle simulated through PIC/MCC with the circuit modules, and the load's voltammetry characteristics can real-time feedback to the Blumlein Pulse Forming Network (BPFN) of the LTD. In contrast to prior simulations that used fitted ideal T-shaped pulse input waveforms to model the load, this method provides a clearer depiction of the influence of gas ionization on the pulse shape. Additionally, the paper conducts simulation studies on LTD electron beam generator operating at different argon gas pressures. The findings indicate that introducing gas can effectively increase current while reducing voltage amplitude, thereby lowering the diode impedance. A small amount of gas can slightly enhance peak power, but excessive gas diminishes peak power and significantly shortens voltage pulse width. This is attributed to the beneficial effect of a small amount of gas ionization-produced plasma on the device. However, an excessive amount of gas ionization-generated plasma can lead to impedance mismatch in the device, even resulting in a load short circuit. This phenomenon causes a decrease in pressure drop at the top, consequently shortening the pulse width.

A repetitive frequency square wave generator based on Blumlein pulse forming network and pseudospark switch.

The Blumlein pulse forming network (PFN) has widely beenused in pulsed power technology to generate square waves with short pulse widths. In this paper, we developed a repetitive frequency square wave generator based on Blumlein PFN and pseudospark switch (PSS). A Blumlein PFN with unequal capacitances has been proposed, and the PFN parameters have been optimized for better output waveforms. A single-gap PSS with a withstand voltage of 40kV and a repetitive frequency of 100Hz has been designed to switch the Blumlein PFN. The experiment results show that the square wave generator can output pulses with a voltage of 26kV, a rise time of 25ns, and a pulse width of 90ns on a matched load of 11Ω. It has operated steadily for 10h with a repetitive frequency of 100Hz, and the jitter remains at around 1ns after 1.05 × 106 shots.

Analyzing and Improving the Output Waveform of Linear Transformer Driver Cavity

The linear transformer driver (LTD) is widely used in the field of pulsed power, especially for generating intense electron beam. The design of an LTD with quasi-rectangular voltage output is presented. The Blumlein pulse-forming network (BPFN) with L-type configuration replaced traditional capacitors to produce a quasi-rectangular voltage waveform; the adding voltage is achieved through a linear transformer (LT) that couples the voltage from multiple primaries to a single secondary. Since the output waveforms of BPFN and LT determine the output waveform of LTD, the effects of the configuration of the BPFN and the parameters of the LT on the output voltage waveform are studied. At the same time, according to the results, the output voltage waveform is improved by optimizing the inductance of the BPFN and selecting the appropriate parameters of the LT. After that, an electron beam generator based on six-stage LTD cavities is developed, and a well-shaped quasi-rectangular waveform is obtained at a planar diode load.

A repetitive long-pulse power generator based on pulse forming network and linear transformer driver.

A compact module for long-pulse power generator, based on Blumlein pulse forming network (PFN), was designed. Two Blumlein PFNs with L-type configuration and 20 Ω characteristic impedance were connected symmetrically to the primary coil of the linear transformer driver (LTD) and driven by an identical high voltage spark switch to ensure two Blumlein PFNs synchronizing operation. The output pulse of the module connected with 10 Ω water load is about 135 kV in amplitude and 200 ns in duration with a rise time of ∼50 ns and a flat top of ∼100 ns. On this basis, a repetitive long-pulse power generator based on PFN-LTD has been developed, which was composed of four modules. The following technical parameters of the generator were achieved on planar diode: output voltage amplitude of ∼560 kV, output current amplitude of ∼10 kA at a repetition rate of 25 Hz. The generator operates stable and outputs more than 10(4) pulses. Meanwhile, the continuous operating time of the generator is up to 60 s.

Electroperturbation of DNA in Jurkat Cells Under Nanosecond Pulsed Electric Fields

Intense (5-30 MV/m) ultra-short (10-300 ns) pulsed electric fields (US-PEFs) have been demonstrated to interact with sub-cellular membranes and structures [Schoenbach et al., IEEE Trans. Diel. El. Ins., 14 (5): 1088-1109, 2007]. Investigating how cells respond to nanosecond pulses is essential for a) development of biomedical applications of US-PEFs, including cancer treatment, and b) better understanding of the mechanisms underlying such bioelectrical effects. T-lymphoblast Jurkat cells were exposed to a single pulse of 60 ns duration and 2.5 MV/m amplitude, without affecting cell growth and viability, to give insight into effects underlying interaction mechanisms. A cuvette-based exposure system, fed by a classical Blumlein pulse-forming network, was employed. A statistically significant reduction in DNA migration was detected immediately after US-PEF exposure by means of the alkaline comet assay [Zeni et al., Sensors, 8: 485-496, 2008]. This effect, associated with plasma membrane poration (YO-PRO-1 uptake) has been demonstrated to recover within 2 hours after pulse delivery (Figure 1), indicating that our exposure protocol targets the nucleus, affecting DNA structure. In our experimental conditions, a transient conformational change in DNA molecule can thus be hypothesized.

基于Blumlein 脉冲形成网络的直线变压器驱动源设计

基于Blumlein 脉冲形成网络的直线变压器驱动源设计

Modified Blumlein Pulse-Forming Networks for Bioelectrical Applications

Intense nanosecond pulsed electric fields (nsPEFs) have been shown to induce, on intracellular structures, interesting effects dependent on electrical exposure conditions (pulse length and amplitude, repetition frequency and number of pulses), which are known in the literature as "bioelectrical effects" (Schoenbach et al., IEEE Trans Plasma Sci 30:293-300, 2002). In particular, pulses with a shorter width than the plasma membrane charging time constant (about 100 ns for mammalian cells) can penetrate the cell and trigger effects such as permeabilization of intracellular membranes, release of Ca(2+) and apoptosis induction. Moreover, the observed effects have led to exploration of medical applications, like the treatment of melanoma tumors (Nuccitelli et al., Biochem Biophys Res Commun 343:351-360, 2006). Pulsed electric fields allowing such effects usually range from several tens to a few hundred nanoseconds in duration and from a few to several tens of megavolts per meter in amplitude (Schoenbach et al., IEEE Trans Diel Elec Insul 14:1088-1109, 2007); however, the biological effects of subnanosecond pulses have been also investigated (Schoenbach et al., IEEE Trans Plasma Sci 36:414-422, 2008). The use of such a large variety of pulse parameters suggests that highly flexible pulse-generating systems, able to deliver wide ranges of pulse durations and amplitudes, are strongly required in order to explore effects and applications related to different exposure conditions. The Blumlein pulse-forming network is an often-employed circuit topology for the generation of high-voltage electric pulses with fixed pulse duration. An innovative modification to the Blumlein circuit has been recently devised which allows generation of pulses with variable amplitude, duration and polarity. Two different modified Blumlein pulse-generating systems are presented in this article, the first based on a coaxial cable configuration, matching microscopic slides as a pulse-delivery system, and the other based on microstrip transmission lines and designed to match cuvettes for the exposure of cell suspensions.

Influence of balance gas mixture on decomposition of dimethyl sulfide in a wire-cylinder pulse corona reactor

The influence of balance gas mixture on decomposition of dimethyl sulfide was investigated experimentally by a wire-cylinder pulse corona reactor at room temperature. A new type of high voltage pulse generator with a thyratron switch and a Blumlein pulse-forming network was used in the experiments. The experiments were conducted at a fixed pulse frequency of 100 pps. The DMS decomposition efficiency as well as energy yield was investigated using varying oxygen concentration (0.6–21.0%), humidity (0–1.0%) and different balance gas (air, N 2, Ar). Breakdown voltage of DMS in Ar is lower than that of DMS in N 2, both of which are proportional to the gas pressures. The conversion of DMS in Ar is more efficient than that in N 2 and air at a fixed peak voltage. In addition, it is found that 5% oxygen is the optimum concentration in decomposition of DMS, due to higher conversion of DMS and relatively fewer yields of by products, such as O 3, NO x and SO 2. The highest DMS removal efficiency where the energy yield was 1.24 mg kJ −1 was achieved with the gas stream containing 0.3% H 2O in air.

Decomposition of dimethyl sulfide in a wire-cylinder pulse corona reactor

Decomposition of dimethyl sulfide (DMS) in air was investigated experimentally by using a wire-cylinder dielectric barrier discharge (DBD) reactor at room temperature and atmospheric pressure. A new type of high pulse voltage source with a thyratron switch and a Blumlein pulse-forming network (BPFN) was adopted in our experiments. The maximum power output of the pulse voltage source and the maximum peak voltage were 1 kW and 100 kV, respectively. The important parameters affecting odor decomposition, including peak voltage, pulse frequency, gas flow rate, initial concentration, and humidity, which influenced the removal efficiency, were investigated. The results showed that DMS could be treated effectively and almost a 100% removal efficiency was achieved at the conditions with an initial concentration of 832 mg/m3 and a gas flow rate of 1000 ml/min. Humidity boosts the removal efficiency and improves the energy yield (EY) greatly. The EY of 832 mg/m3 DMS was 2.87 mg/kJ when the relative humidity was above 30%. In the case of DMS removal, the ozone and nitrogen oxides were observed in the exhaust gas. The carbon and sulfur elements of DMS were mainly converted to carbon dioxide, carbon monoxide and sulfur dioxide. Moreover, sulfur was discovered in the reactor. According to the results, the optimization design for the reactor and the matching of high pulse voltage source can be reckoned.

A method of water-bloom prevention using underwater pulsed streamer discharge

Water-bloom (also named as cyanobacterial bloom) is becoming a very serious pollution problem all over the world. In this paper, a new method for the prevention of water blooms using underwater streamer discharges is reported. Blumlein pulse forming network (B-PFN) and magnetic pulse compression circuit (MPC) were employed to apply high voltage pulses to water with cyanobacterial cells. The experimental results confirmed that the cyanobacterial cells sank to the bottom of the water bodies after applying underwater streamer discharges. Transmission electron microscope (TEM) observations showed that the discharge collapsed the gas vesicles (GVs)—the intercellular structure of water-bloom forming cyanobaterial cells—and did not affect the other part of contents of the cells. Cynabacterial cells lost buoyancy and sank to the bottom of the water bodies. Because of lower temperature and without enough sunlight at the bottom of the water bodies, the cells can be prevented from proliferation too quickly.

Compact high repetition rate pseudospark pulse Generator

A pseudospark-based high repetition rate pulse generator, together with a resonant charging power supply is presented. The pulse generator was developed for research applications that include transient plasma ignition. The design incorporates a lumped element Blumlein pulse-forming network that is switched by a commercial pseudospark into an output pulse transformer with a METGLAS core. The Blumlein is charged up to 30 kV by a resonant capacitor charger, based on a fly-back transformer and high-power insulated gate bipolar transistor (IGBT) switch module. The output voltage of the charger is controlled by the on-time of the IGBT. Pulses with duration of 50 ns can be generated at a 2.6-kHz maximum repetition rate. Pulses with amplitude up to 90 kV can be delivered into a 200-/spl Omega/ load.

Decomposition of Mixed Malodorants in a Wire-Plate Pulse Corona Reactor

Decomposition characteristics of two groups of representative mixed malodorants (1, ethanethiol + hydrogen sulfide; 2, ethanethiol + ammonia) in air were investigated employing a wire-plate pulse corona reactor. A new type of high-voltage pulse generator with a thyratron switch and a Blumlein pulse-forming network (BPFN) was used in our experiments. The experiments were conducted at a gas-flow rate of 13 m3/h. Important parameters, including peak voltage, chemical structures of malodorants, pulse frequency, and initial concentration, which influenced the removal efficiency, were investigated. The results showed that the mixed malodorants could be treated effectively by pulse corona. The removal efficiencies of 200 mg/m3 C2H5SH and 200 mg/m3 H2S for group 1 were 95.6% and 100%, respectively, which were almost equal to those of the two pollutants separately. The energy cost was about 65.1-81.4 J/L, which was 31.5-45.2% lower than for treating pollutants alone. The removal efficiencies of 105 mg/m3 C2HsSH and 40 mg/m3 NH3 for group 2 were 93.1% and almost 100%, and the energy cost was 65.1 J/L, 55.6% lower than that which was treated separately. In the case of two groups of mixed malodorants removal, NOx, 03, SO2, CO2, and CO were all observed. Moreover, some sulfur and white crystal ammonium nitrates were discovered adhering to the corona wires in the removal of groups 1 and 2, respectively. A dynamics model was developed to describe the relation of the removal efficiency with specific energy density and initial concentration. In the case of group 1 removal,the decomposition rate constants decreased as compared to the single treating. As for group 2 removal, the decomposition rate constants increased, especially for NH3. According to the results, the optimization design for the reactor and the matching of high pulse voltage source can be reckoned.

Decomposition of simulated odors in municipal wastewater treatment plants by a wire-plate pulse corona reactor

Decomposition of simulated odors in municipal wastewater treatment plants was investigated experimentally by a wire-plate pulse corona reactor. A new type of high pulse voltage source with a thyratron switch and a Blumlein pulse forming network (BPFN) was adopted in our experiments, and the testing malodorants were ammonia, ethanethiol and tri-methyl amine, respectively. The maximum output power of the pulse voltage source and the maximum peak voltage were 1 kW and 100 kV. The experiments were conducted at the gas-flow rate of 4.0–23.0 m 3 h −1. Important parameters, including peak voltage, pulse frequency, capacitance (inductance) of the BPFN, gas-flow rate, initial concentration, which influenced on the removal efficiency, were investigated. The results show that the odors can be treated effectively. Almost 100% removal efficiency was obtained for 32 mg m −3 ammonia at the gas-flow rate of 4.0 m 3 h −1. The maximum removal efficiencies of 85 mg m −3 ethanethiol and 750 mg m −3 tri-methyl amine at 10.0 m 3 h −1 were 98% and 91%, respectively. The energy yield of 110 mg m −3 ammonia was 2.99 g kW h −1 when specific energy density was 106 J l −1. In the cases of ammonia, ethanethiol and tri-methyl amine removal, ozone and nitrogen oxides were observed in the exit gas. The carbon and sulfur elements of ethanethiol and tri-methyl amine were mainly converted to carbon dioxide, carbon monoxide and sulfur dioxide. Moreover, the ammonium nitrates and sulfur were discovered in the reactor.

Frequency and Bandwidth Agile Pulser for Use in Wideband Applications

We have developed an architecture to produce a wideband pulser that is tunable in the important parameters of pulsewidth, bandwidth, and center frequency. The pulser is based on a parallel plate Blumlein pulse-forming network (PFN) with a movable center (charge) conductor. When the center conductor is displaced from the ideal Blumlein position, the balance in the PFN is lost, resulting in a slightly ringing waveform that can be tuned. By selecting the amount of ringing, the output bandwidth of the PFN can be adjusted. Furthermore, by simply sliding the center conductor out of the PFN, the effective electrical length can be adjusted, allowing the fundamental period of the ringing waveform to be altered, thereby changing the center frequency of the output waveform. Our pulser is designed to operate in the range of 300 MHz to 2 GHz, but the architecture is scalable outside this range. In this paper, we present design and simulation results, low-voltage tests, and preliminary high-voltage (15-kV) data that is obtained with a pressurized gas trigatron designed specifically for this test fixture. The pulser is being designed for laboratory use in testing the effects of interaction of high-intensity wideband electromagnetic fields with small-scale electrical and biological systems.