Blumlein Generator Research Articles

In brief

PAGE 886 Researchers in South Korea present a near-field sheet-like wave-guide as a transmitter, and cylindrical wave-cavity as a receiver, for a wireless power/data transfer device. The device is designed to sustain transmission capabilities despite the variations in thickness of metal walls. The system operates at 25 Mhz and achieves data transfer rates of 50 Mbps. PAGE 853 A technique that significantly reduces the radiated field generated by wireless powered biomedical implants has been proposed in work from the US. The reduction in the radiated field is achieved using a multi-coil wireless power transfer (WPT) system instead of a traditional two-coil WPT design, achieving higher power transfer efficiency, with the same voltage gain and frequency bandwidth, over the same operating distance as a two-coil system. The wireless power/data transfer device is aimed at applications in the shipping industry to alleviate cabling installation issues PAGE 881 Researchers in Germany present the first implementation of integrated mm-wave circuits as radiation sources and detectors for high-resolution mm-wave gas spectroscopy. The results offer a path towards a very compact, low-cost system for gas spectroscopy, using advanced SiGe BiCMOS technology with potential security, forensic and medical applications, including breath analysis. The proposed technique reduces radiated fields generated by wirelessly powered biomedical implants PAGE 850 Work in Australia addresses issues faced by researchers in building effective, compact, microwave-based brain stroke detection systems requiring low profile, compact, directive, wideband antennas for imaging. Utilising the plane of magnetic symmetry, the antenna reported reduces space requirements by half, allowing the diagnostic system to allocate twice the number of antenna elements in the array. Increased data collection results in clearer images for stroke detection. Millimetre wave circuits as radiation sources and detectors utilised in gas spectroscopy may have security and medical applications PAGE 859 The Blumlein configuration is an effective approach to generate high voltage short pulses. Researchers in the United States present on chip Blumlein generators, along with an on-chip broadband Klophenstein taper, to convert high-impedance loads to 50 Ω. This simple and compact Blumlein pulse generator may be implemented in MEMS/NEMS actuation and biomedical studies. Proposed antenna allows clearer images to be produced for detection of strokes in patients Simple and compact Blumlein pulse generator may be implemented in micro/nano-electromechanical systems

On‐chip Blumlein pulse generator

A CMOS Blumlein generator including a two-stacked-metal–oxide semiconductor field effect transistor high-voltage switch, a Blumlein pulse-forming-line (PFL) network and an on-chip Klophenstein taper is presented. The Klophenstein taper is used to convert the high-impedance load to 50 Ω. The Blumlein pulse generator is fabricated in a 0.13 µm CMOS process. Gaussian-like pulses of 725 mV peak-to-peak amplitude, ∼126 ps duration and 3.18 GHz bandwidth are measured on a 50 Ω load (including the losses of the probes, cables and pads). After de-embedding the connection system and Klophenstein taper, the pulses of 1.88 V and 114 ps duration are obtained, which are higher than the rated operating power supply of the given process.

Modeling of a Solid-State Bipolar Blumlein Generator for $n$ Stages

This paper models an n-stage stacked Blumlein generator for bipolar pulses for various load conditions. Calculation of the voltage amplitudes in time domain at the load and between stages is described for an n-stage generator. For this, the reflection and transmission coefficients are mathematically modeled where impedance discontinuity occurs (i.e., at the junctions between two transmission lines). The mathematical model developed is assessed by comparing simulation results to experimental data from a two-stage Blumlein solid-state prototype.

Modeling Double Blumlein with Variable Duration and Polarity using Orcad PSpice

Double Blumlein generator is an excellent technique in generating high voltage short pulsed power with fast rise time signal. However properties of fixed pulse duration and polarity of Blumlein configuration limits the generator flexibility and efficiency. A modeling of double Blumlein with double switching configuration with controlled delay is proposed in this paper to solve the limitation problem. The circuit is modeled in PSpice environment and the result successfully showed double output pulse voltage of flat top square waveform with adjustable duration and polarity.

Blumlein Configuration for High-Repetition-Rate Pulse Generation of Variable Duration and Polarity Using Synchronized Switch Control

Blumlein generators are used in different applications such as radars, lasers, and also recently in various biomedical studies, where the effects of high-voltage nanosecond pulses on biological cells are evaluated. In these studies, it was demonstrated that by applying high-voltage nanosecond pulses to cells, plasma membrane and cell organelles are permeabilized. As suggested in a recent publication, the repetition rate and polarity of nanosecond high-voltage pulses could have an important effect on the electropermeabilization process, and consequently, on the observed phenomena. Therefore, we designed a new Blumlein configuration that enables a higher repetition rate of variable duration of either bipolar or unipolar high-voltage pulses. We achieved a maximal pulse repetition rate of 1.1 MHz. However, theoretically, this rate could be even higher. We labeled endocytotic vesicles with lucifer yellow and added propidium iodide to a cell suspension for testing the cell plasma membrane integrity, so we were able to observe the permeabilization of endocytotic vesicles and the cell plasma membrane at the same time. The new design of pulse generator was built, verified, and also tested in experiments. The resulting flexibility and variability allow further in vitro experiments to determine the importance of the pulse repetition rate and pulse polarity on membrane permeabilization -- both of the cell plasma membrane as well as of cell organelle membranes.

Positive- and Negative-Pulsed Streamer Discharges Generated by a 100-ns Pulsed-Power in Atmospheric Air

A Blumlein generator that has a pulsewidth of 100 ns was used to investigate the process of streamer discharge propagation in a coaxial cylindrical reactor using a streak camera. Both positive and negative polarities of the streamer discharges were performed in air at atmospheric pressure. The results showed that the primary and secondary streamers propagated with increasing velocity from the central rod to the outer cylinder electrode in both positive and negative polarities of applied voltages to the rod electrode. The propagation velocity of the streamer heads was in the range of 0.8-1.2 mm/ns for a positive peak applied voltage in the range of 43-60 kV and 0.6 mm/ns for a negative peak applied voltage of -93 kV, respectively. The electric field at streamer onset was calculated to be 12 and 20 MV/m for positive and negative applied voltages, respectively.

Novel multiple-switch Blumlein generator

The Blumlein generator has been one of the most popular pulsed-power circuits. The pulse forming lines are charged simultaneously, and then discharged via a single switch, such as a spark gap. The generator can be used for single pulse or at a high repletion rate. However, for large pulsed power generation, one critical issue for such a single-switch based circuit topology is related to large switching currents. In this article, we propose a novel Blumlein circuit topology based on multiple switches. The pulsed forming lines are charged in parallel and then are synchronously commutated via multiple switches. No special synchronization trigger circuit is needed for the proposed circuit topology; this robust circuit topology is simple and very reliable. A prototype multiple-switch Blumlein generator with two spark-gap switches has been experimentally evaluated with both resistive and corona plasma loads. In terms of the switching currents, it is observed that the two switches can be synchronized within 2–3 ns. The energy conversion efficiencies are 82% and 76.8% for a matched resistive load and a plasma reactor, respectively.

Bacteria Decontamination by Pulsed Power.

In order to explore the effect of Pulsed Electric Fields (PEF) with pulses on the order of the charging time of bacterial membranes, we studied the effect of 45 ns pulses on the viability of bacillus subtilis in its vegetative state. A 30 Ω Blumlein generator with a low inductance spark gap switch delivers square wave voltage pulses of 45 ns duration to the electrodes in the bacterial treatment chamber. The rise time, which was varied from 2 ns (f< 200 MHz) to 20 ns (f< 50 MHz), determines the high frequency components in the Fourier spectrum of the pulse. Among pulses of different rise times, having the same total energy, those with the shortest rise time were found to kill bacteria more effectively. These results indicate that the high frequency components in the PEF deposit the electrical energy in the cell and affect intracellular structures.

Design of a 150 kV 300 A 100 Hz Blumlein coaxial pulser for long-pulse operation

Blumlein pulse generators have been used with great success for high voltage pulse generation. They are capable of producing pulses in the nanosecond or microsecond ranges depending on the transmission line length and on the topology used. The main problem with this type of generators relates to the presence of stray lines that degrade the overall gain of the device. In this paper, we are proposing a design method of a 150 kV/300 A coaxial Blumlein pulser with pulse duration of 1 /spl mu/s in which the parasitic effects are minimized by winding the transmission lines on coil formers. Also we have developed a model that estimates the pulser voltage gain from just two parameters: the number of stages and the impedance ratio of the transmission line characteristic impedance and the parasitic secondary mode impedance. The model can be applied to other types of Blumlein generators with different geometries such as those made of strip transmission lines.

Study of a fast, high-impedance, high-voltage pulse divider

A novel two-tube, two-stage, self-compensating resistive voltage divider with minimized stray capacitance using copper sulphate solution was explored to measure a fast high-impulse voltage output from a cable Blumlein generator. Self-compensation of the probe was achieved by matching the RC time constant in the two dividing stages. Stray capacitance of the probe was minimized by electric field contouring and matching methods. Experiments were carried out to investigate the probe responses as affected by self-capacitance, impedance, and stray capacitance. Calibration of the optimized probe showed a rise time of 15 ns at a load impedance of 8.68 kΩ with a hold-off voltage of 600 kV.

Repetitive operation of water-filled Blumlein generator

A water-filled Blumlein generator was operated at different repetition rates of up to 15 Hz, and its temporal performance was investigated. The Blumlein generator having an impedance of 10 Ω provides a rectangular voltage pulse with an amplitude of 200 kV and a duration of 75 ns into a matched load. The resistance of the water in the line decreases quickly at &amp;gt;10 Hz during a continuous operation for an hour and results in a decrease in the output voltage of the Blumlein line. The generator works with a repetition rate of up to 6 Hz without serious degradation in the voltage, while the averaged power density dissipated in the water is approximately 40 mW/cm3. The increase in the water temperature during operation is only a few degrees. This implies that the resistive heating of the water is not the dominant cause of the decrease in the water resistance.

Inactivation of Bucillus Stearothermophilus by pulsed electric field

B. Stearothermophilus remains alive even under intense electric field, since spores formed are highly resistant to damage from electric field effects. This paper describes the effects of pulsed electric field on B. Stearothermophilus (ATCC no, 12980). An aqueous suspension of B. Stearothermophilus spores was placed between parallel planar electrodes and subjected to pulsed electric fields of up to 189 kV/cm, which are obtained from a high-voltage pulsed voltage generator. Either a Blumlein generator or a magnetic compression circuit with a semiconductor opening switch was used as the pulsed voltage generator. The spores that survived the treatment were detected by a colony counting method. The growth activities were measured using a microbial calorimetry technique. The temperature and pH of the spore suspension remained unchanged during the treatment. It was found that the growth activity of B. Stearothermophilus was affected by the pulsed electric field. while no remarkable lethal effect was observed in the range of up to 40 kV/cm.

Characterization and realization of a 120 kV, 200 ns transmission line pulse generator

A 120 kV / 200 ns / 13 J transmission line generator building is accurately studied. A design method for achieving compact and reliable Blumlein generators is elaborated and validated by three realizations. In order to estimate the transmission line transformer amplification and droop, a set of equations is established and a new simplified gain expression is suggested. Another set of equations to characterize the secondary parasitic lines is settled. By turning it to account, an innovating building method using iron powder to reduce the transmission line transformer parasitic effects, is proposed. In this case, the transmission line generator energy yield reaches 93%.

Flash X-ray sources powered by Blumlein pulse generators

Described here is the progress in construction and characterization of pulse-power generators capable of discharging at high repetition rates. These devices consist of several triaxial Blumleins stacked in series at one end. The lines are charged in parallel and synchronously commuted with a single thyratron at the other end. In this way relatively low charging voltages are multiplied to give the desired discharge voltage without the need for complex Marx bank circuitry. Scaling of these stacked Blumlein generators to obtain open circuit voltages in excess of 0.5 MV is reported. Peak power generated by discharging into an X-ray diode exceeds 10 7 R/s and high repetition rates allow for an average emitted X-ray exposure rate of 25 R/s from a sequence of 40 ns pulses.

Production of high-energy photons from flash x-ray sources powered by stacked Blumlein generators

Described here is the design and construction of a pulse-power generator capable of discharging at high repetition rates. It consists of eight triaxial Blumleins stacked in series at one end. These lines are charged in parallel and synchronously commuted with a single thyratron at the other end to produce an open circuit voltage across a stack of six times the charging voltage. An x-ray diode has been constructed and matched to this pulse-power source making possible the emission of an average bremsstrahlung exposure rate of 17 R/S from a sequence of 40-ns pulses. When operated at 60-kV charging voltage, direct spectral measurements show the output to be a true continuum, peaking at intensities in excess of 5×108 photons/keV/shot and containing useful intensities of photons having energies of 300 keV.

Energetic flash X-ray sources excited by Blumlein generators

Eight triaxial Blumlein circuits have been stacked in series at one end while being synchronously commuted at the other end with a single hydrogen thyratron. Having no other switching elements, operation has been possible at repetition rates up to 100 Hz. Improvement in matching an X-ray diode to this pulse power source has been realized, making possible the emission of an average bremsstrahlung exposure rate of 15 R/s from a sequence of 20 ns pulses. Recent advances in the development of this device resulting in open-circuit voltage gains approaching six times the charging voltage are described.

Flash x-ray source excited by stacked Blumlein generators

Eight triaxial Blumleins have been stacked in series at one end while being synchronously commuted at the other end with a single hydrogen thyratron. Significant voltage gain has been maintained in the stack for periods of the order of 20 ns. Having no other switching elements, operation has been possible at repetition rates to 100 Hz. An x-ray diode has been matched to this pulse power source, making possible the emission of an average bremsstrahlung dose of 5.8 R/s from a sequence of 20-ns pulses. In less than 4 min of operation at 100 Hz, a dose of 1 kR could have been delivered to a target sample. When operated at 50-kV charging voltage, spectral measurements show the output to be a true continuum, peaking at intensities in excess of 2×108 keV/keV/shot and containing useful intensities of photons having energies of 150 keV.

Current Evolution in a Pulsed Overstressed Radial Vacuum Gap

The evolution of current in a radial, two element, vacuum gap has been studied as a function of applied voltage. Gap spacings of 1 and 2 mm, between coaxial brass electrodes, at a pressure of 1×10-2 Pa, have been used. Voltage pulses between 20 kV and 176 kV, with 15 ns risetimes and 50 ns durations, have been applied to the vacuum gap using a water-filled Blumlein generator having a source impedance of 10 Ω. The data indicate that voltages on the order of 32 and 60 kV can be applied to 1 and 2 mm gaps, respectively, without drawing currents larger than 100 A during the excitation time. For applied voltages greater than 60 kV, current approximately equal to the short circuit value was observed in a 1 mm gap. For higher voltage excitations, breakdown delays on the order of 5 ns, with an initial current rate of rise of up to 8×1011 A/s, have been obtained.

Space-Charge Effects in a Laser Fiber-Optics Triggered Multichannel Spark Gap

The dual channel triggering of a spark gap switch by fiberoptic transported ruby laser radiation is discussed. The spark gap is the output switch of a 20-ns water dielectric Blumlein generator. The Blumlein generator is pulse charged in approximately 250 ns by a three-stage Marx bank to 150 kV. The spark gap is operated at a pressure of 2540 torr with a mixture of Ar and N2 gas and an electrode separation of 2 cm. Two 1-mm diameter quartz optical fibers are used to transport 2 2-MW laser beams into the spark gap onto points 6 cm apart on the target electrode. The two beams are obtained by optical splitting of the output of a single laser. Under appropriate conditions, two arc channels are initiated by the laser beams along their paths. A small improvement in current rise time for dual channel events over single channel events is observed. Moreover, the number of successful dual channel events is observed to depend on the time of laser entry with reference to the beginning of the charging pulse, and not the gap polarity. The correlation of this behavior with the space charge build up in the slightly over-volted gap is discussed.

Laser Triggering through Fiber Optics of a Low Jitter Spark Gap

An optical filter is employed to transport a 15-ns light pulse from a high power ruby laser for precise triggering of a gas filed high voltage spark gap. The maximum power density that can be transmitted by the fiber is limited to 6 × 1012 W/m2 above which laser induced damage occurs on the fiber entrance face. The overall throughput efficiency of the optical system was measured as 62 percent. Results are presented for the switching delay time and associated jitter for various mixtures of A and N2 gas, and as a function of the voltage across a pulse-charged Blumlein generator gap. Pulse charging of the Blumlein generator was accomplished by a three-stage Marx generator, resulting in output voltages up to 250 kV. It was conclusively demonstrated that an optical fiber will transport a sufficiently intense laser pulse to evince subnanosecond jitter in the triggering of a pressurized gas switch under the conditions studied.