High-frequency Pulse Generator Research Articles

Wavelength-tunable high-repetition-rate pulse generation in a SOA-based fiber laser with gain instability

Abstract Introducing negative optical feedback into a semiconductor optical amplifier-based laser presents a straightforward and effective approach for generating high-repetition-rate pulses through the mechanism of self-sustaining cross-gain modulation. In this work, we demonstrate, for the first time, the tunability of high-frequency pulse generation over a wide wavelength range by adjusting the central transmission wavelength of a tunable filter. Our laser system achieved a full tuning range from 1480 nm to 1556 nm (76 nm) while maintaining pulsed lasing. Remarkably, the laser exhibited a maximum pulse contrast exceeding 85% over a tuning range of 43 nm, from 1505.7 nm to 1548.7 nm. At any wavelength within this range, stable, self-starting pulse generation was consistently achieved, with a pulse repetition rate of 1.3 GHz.

МОРСЬКИЙ БЕЗПІЛОТНИЙ УДАРНИЙ ДРОН-КАТЕР ІЗ УЛЬТРАЗВУКОВИМ ПРИШВИДШУВАЧЕМ РУХУ

A description of the design scheme of a marine unmanned attack drone-boat with an ultrasonic accelerator is given. Its increase in speed at the final stage of reaching a target pre-selected by the operator is provided by an ultrasonic generator of high-frequency electromagnetic waves installed in the hull of the drone-boat, the emitters of which are placed on the hull below its waterline to irradiate the water in which the hull moves and disturb its cavitation. It was found that the use of an ultrasonic generator, which includes a high-frequency pulse generator with an electrical power source, an amplifier with a resonator, and an emitter of ultrasonic high-frequency electromagnetic waves, is optimal for disturbing cavitation in offshore water. The emitters are washed with onboard water and are arranged in a staggered pattern on the boat's hull and bottom below its waterline. It has been proven that the disturbance of the cavitation field under the bottom of the moving hull of the boat in offshore water reduces the viscosity of water by 30-40%, thereby reducing the hydrodynamic resistance of water by moving solid bodies in it. It was found that lowering the hydrodynamic resistance of the water on board contributes to increasing the speed of the boat's hull from its cruising speed of 75-80 km/h in the final section of the approach to the target to 95-100 km/h. It is noted that increasing the boat's speed contributes to a proportional increase in the kinetic energy of its impact on a previously selected target, increasing the degree of damage and destruction caused to the target. It is estimated that increasing the speed of the drone-boat by 25-30% guarantees a 25-26% reduction in the duration of its stay in the affected area and, accordingly, proportionally lowers the probability of it being hit by the enemy's automated small arms. It is recommended to choose the design scheme and structure of powerful typical devices for ultrasonic welding as an ultrasonic generator of ultrasonic pulsating electromagnetic wave radiation. Their cheap parts and assemblies are mass-produced by industrial enterprises.

An Inductive Isolation-Based 10 kV Modular Solid Boost-Marx Pulse Generator

The solid-state Marx pulse generator is widely used in various fields such as biomedical electroporation, food processing, and plasma material modification. In this paper, an inductor is chosen as an isolation device and by adding a switch to the circuit, a solid-state boost-Marx pulse generator (BMPG) is formed. On the one hand, the inductor forms a boost circuit to multiply the output voltage gain, and on the other hand, it solves the shortcomings of conventional Marx pulse generators where the charging speed and total efficiency during high-frequency pulse generation are drastically affected by the isolation resistor. The selection criteria for inductors is well derived. Based on the PSpice simulation verification, a 12-module prototype of BMPG is built. The test results show that the circuit can achieve 10 kV high-voltage pulse output with a pulse width of 200–1000 ns and an adjustable repetition frequency of 0–10 kHz. While the input DC voltage requirement is only 235 V, the pulse voltage boost multiple is up to 42.5 times. Additionally, with the different switching sequences, the proposed BMPG can realize the adjustable change of pulse rising time and falling time.

Four Channel 6.5 kV, 65 A, 100 ns–100 µs Generator with Advanced Control of Pulse and Burst Protocols for Biomedical and Biotechnological Applications

Pulsed electric fields in the sub-microsecond range are being increasingly used in biomedical and biotechnology applications, where the demand for high-voltage and high-frequency pulse generators with enhanced performance and pulse flexibility is pushing the limits of pulse power solid state technology. In the scope of this article, a new pulsed generator, which includes four independent MOSFET based Marx modulators, operating individually or combined, controlled from a computer user interface, is described. The generator is capable of applying different pulse shapes, from unipolar to bipolar pulses into biological loads, in symmetric and asymmetric modes, with voltages up to 6.5 kV and currents up to 65 A, in pulse widths from 100 ns to 100 µs, including short-circuit protection, current and voltage monitoring. This new scientific tool can open new research possibility due to the flexibility it provides in pulse generation, particularly in adjusting pulse width, polarity, and amplitude from pulse-to-pulse. It also permits operating in burst mode up to 5 MHz in four independent channels, for example in the application of synchronized asymmetric bipolar pulses, which is shown together with other characteristics of the generator.

Concepts and Capabilities of In-House Built Nanosecond Pulsed Electric Field (nsPEF) Generators for Electroporation: State of Art

Electroporation is a pulsed electric field triggered phenomenon of cell permeabilization, which is extensively used in biomedical and biotechnological context. There is a growing scientific demand for high-voltage and/or high-frequency pulse generators for electropermeabilization of cells (electroporators). In the scope of this article we have reviewed the basic topologies of nanosecond pulsed electric field (nsPEF) generators for electroporation and the parametric capabilities of various in-house built devices, which were introduced in the last two decades. Classification of more than 60 various nsPEF generators was performed and pulse forming characteristics (pulse shape, voltage, duration and repetition frequency) were listed and compared. Lastly, the trends in the development of the electroporation technology were discussed.

Triangular pulse generation by using chalcogenide fibers and creation of tunable High frequency oscillations from the Interaction of reshaped pulse pair

Designing few normal dispersion chalcogenide fibers leads to obtain a Normal Dispersion Decreasing Chalcogenide Fiber with a value of group velocity dispersion (β2) varying from ∼ 240.45 ps2/km to 221.52 ps2/km and nonlinear coefficient (γ) within a range from ∼ 62.82 W−1 km−1 to 108.17 W−1 km−1 throughout a fiber length of 75 m. The so designed fiber is preferable for generation of Triangular Pulse at relatively shorter optimum length (Lopt) when compared to previously reported works. Such reshaped pairs of triangular pulses interact as their tails start to overlap while propagating through the fiber and generates high frequency (∼THz) oscillating pulse train. This frequency can be easily altered in a controlled manner by carefully changing the propagation length or the separation between the input pulse pair. The so designed fiber alongwith the optimum input pulse parameters can be potentially applied in the domain of tunable high frequency pulse generators along with many standard applications of TP.

Design and Implementation of a Compact 20-kHz Nanosecond Magnetic Pulse Compression Generator

A compact magnetic pulse compression (MPC) topology with only two magnetic cores and a continuous repetition rate of 20 kHz is presented. The demand for higher average output powers of pulsed power systems can be achieved by an increase of the pulse rate frequency (PRF). The PRF is often limited by the switching speed or recovery of the main switch and also the complex behavior of the magnetic materials. With the advent of insulated gate bipolar transistors and the nanocrystalline soft magnetic material, PRFs of tens of kilohertz are feasible if a suitable MPC topology is applied. The presented MPC is based on an existing topology that has been significantly improved to enable high-frequency pulse generation. A design method using 3-D magnetostatic and transient magnetic simulations is introduced to enable optimization of the magnetic switching components. A 20 kHz, 60 kV, and 52 ns full width at half maximum (FWHM) MPC generator is designed, built, and tested for a $100~\Omega $ load. Simulations suggest that a PRF up to 50 kHz is achievable, but continuous operation will likely be limited by thermal management.

Design of High Voltage and High Frequency Pulse Generator Using DC Choke

Pulsed Electric Field (PEF) processing has demonstrated a high potential for various applications ranging from extraction of valuable components from different biological objects to water treatment. Therefore, high voltage and high frequency pulse generator design is essential in order to fulfill the requirement of a PEF processing system. A high voltage and high frequency pulse generator using DC choke is proposed in this works as solution to increase the pulse train amplitude. The DC choke was verified using function generator to identify its operating frequency and voltage. Results showed that the operating frequency of the DC choke was between 24 kHz to 35 kHz and that it was able to retain the pulse shape of the input pulse train. These results show the ability of the DC choke as a potential solution to increase the pulse amplitude of a pulse train while retaining its shape and duty cycle by cascading it with other power topologies to produce high voltage and high frequency pulse generator for various applications.

Cold Atmospheric Plasma, Created at the Tip of an Elongated Flexible Capillary Using Low Electric Current, Can Slow the Progression of Melanoma.

IntroductionCold Atmospheric Plasma Jet (CAPJ), with ion temperature close to room temperature, has tremendous potential in biomedical engineering, and can potentially offer a therapeutic option that allows cancer cell elimination without damaging healthy tissue. We developed a hand-held flexible device for the delivery of CAPJ to the treatment site, with a modified high-frequency pulse generator operating at a RMS voltage of <1.2 kV and gas flow in the range 0.3–3 l/min. The aims of our study were to characterize the CAPJ emitted from the device, and to evaluate its efficacy in elimination of cancer cells in-vitro and in-vivo.Methods and ResultsThe power delivered by CAPJ was measured on a floating or grounded copper target. The power did not drastically change over distances of 0–14 mm, and was not dependent on the targets resistance. Temperature of CAPJ-treated target was 23°-36° C, and was dependent on the voltage applied. Spectroscopy indicated that excited OH- radicals were abundant both on dry and wet targets, placed at different distances from the plasma gun. An in-vitro cell proliferation assay demonstrated that CAPJ treatment of 60 seconds resulted in significant reduction in proliferation of all cancer cell lines tested, and that CAPJ activated medium was toxic to cancer cells. In-vivo, we treated cutaneous melanoma tumors in nude mice. Tumor volume was significantly decreased in CAPJ-treated tumors relatively to controls, and high dose per fraction was more effective than low dose per fraction treatment. Importantly, pathologic examination revealed that normal skin was not harmed by CAPJ treatment.ConclusionThis preliminary study demonstrates the efficacy of flexible CAPJ delivery system against melanoma progression both in-vitro and in-vivo. It is envisioned that adaptation of CAPJ technology for different kinds of neoplasms use may provide a new modality for the treatment of solid tumors.

High-Voltage, High-Frequency Pulse Generator for Nonequilibrium Plasma Generation and Combustion Enhancement

This paper outlines the design and implementation of a solid-state high-voltage, high-frequency pulse generator used to drive capacitive loads and particularly, nonequilibrium plasmas at atmospheric pressure. The generator is capable of producing open circuit pulses of 0–12 kV with a 300 ns duration (full-width at half-maximum) at a repetition frequency of 0–25 kHz. The working principles of the generator are presented, along with its electrical diagnostics to illustrate its operation with capacitive loads. The generator was applied to a pin-to-plane electrode configuration to generate a diffuse nonequilibrium plasma discharge with peak voltage of 12 kV. Energy deposition and average power required to drive the discharges in open air at 25 kHz were calculated to be 112 $\mu \text{J}$ /pulse and 2.80 W. The generator was also applied to lean, stagnation-plate stabilized V-shaped flames to increase their blowoff velocity. A 28%–51% increase of the blowoff velocity is observed using a discharge with the peak voltage of 6.2 kV, and the repetition rate of 25 kHz.

Elastic constants measured from acoustic wave velocities in barium titanate piezoelectric ceramics

The longitudinal and transverse wave velocities in barium titanate (BT) ceramics sintered at different firing temperatures were measured using an ultrasonic precision thickness gauge with high-frequency pulse generation to evaluate elastic constants, such as Young’s modulus and Poisson’s ratio. With increasing firing temperature, the longitudinal and transverse wave velocities increased; as a result, Young’s modulus increased because of BT ceramics being mechanically hard. Poisson’s ratio after DC poling, however, was almost independent of the firing temperature. It was confirmed that there was an important factor for generating piezoelectricity regarding changes in Young’s modulus and Poisson’s ratio after DC poling compared with those before DC poling, that is, lowering Young’s modulus and increasing Poisson’s ratio. Furthermore, the modulus of rigidity and bulk modulus increased with the firing temperature because of the increase in ceramic bulk density. The modulus of rigidity decreased and the bulk modulus increased during DC poling because of domain alignment.

CEP ef fects on monochromatic high frequency pulse generation from Thomson backscattering

Carrier-envelope phase effect of the monochromatic high frequency pulse generation from Thomson backscattering is investigated with an analytical model and verified by one dimensional particle in cell simulations. We show that the central frequency of the monochromatic light generated from Thomson backscattering is extremely sensitive to the carrier-envelope phase of the field driving the relativistic electron layers.

Optical high-frequency pulse generation with wavelength tunability by using a DBR laser with vernier-type gratings

An optical high-frequency pulse generation method with wavelength tunability is presented by taking advantage of vernier-type gratings in a distributed Bragg reflector laser diode. Experimental results showed that sinusoidal optical pulses, whose lasing wavelengths were tunable, were created with repetition frequencies around 30 GHz. The widths of the radio frequency spectra, furthermore, were drastically reduced by means of mode locking with externally injected optical pulses.

A high-power, high-frequency pulse generator based on a hollow-cathode discharge

A high-power high-frequency generator based on a hollow-cathode gas discharge is described. This simple device, equipped with a cold cathode, produces high-frequency pulses with up to 200-kW of power in a frequency band of 20–60 MHz. The duration of the high-frequency pulses varies from 0.5 to 1.5 μs.

High-frequency pulse generators based on SOS diodes with subnanosecond current cutoff time

Compact high-voltage generators with a pulse power of 100–500 MW, an output voltage of 150–400 kV, a pulse duration of 3–6 ns, and pulse repetition rates of 300–400 Hz and up to 5 kHz in a steady-state and a 30-s-long burst mode, respectively, are described. The output power-amplification unit is based on an inductive storage and SOS diodes with subnanosecond current cutoff time. Physical processes in the semiconductor structure of a SOS diode operating in the subnanosecond current cutoff mode are considered. The generator circuit designs and their test results are presented.

High-speed operation of RSFQ circuits up to 30 GHz

We have experimentally demonstrated high-speed operation of RSFQ circuits using on-chip testing system and confirmed normal operation up to 30 GHz. The system includes high-frequency pulse generators and shift registers (SRs) serving as an interface circuit between high-speed internal signals and low-speed external signals. We adopted two ladder-type pulse generators. One generates clock pulses of 10 GHz and the other generates 25 GHz. By increasing bias currents of JTLs, clock pulses can be generated at higher frequency. By using the system, an SR and a T flip-flop (TFF) gate are examined. The circuits were fabricated by NEC's standard process based on Nb/AlOx/Nb junction technology with Jc = 2.5 kA cm-2. We optimized circuit parameters by using Monte Carlo simulation. In addition, the effect of parasitic inductances can be reduced by decreasing Ic. As a result, the systems for SR and TFF worked correctly up to 30 GHz and 27.5 GHz, respectively. The SR and TFF have wide bias margins of ±39% and ±20%, respectively. We confirmed that the bias margins of the SR are independent of operation frequency. The limits of operation frequency are thought to be much higher than 30 GHz.

The role of high-frequency ventilation in post-traumatic respiratory insufficiency

Post-traumatic pulmonary insufficiency or the adult respiratory distress syndrome is not infrequently associated with multiple organ-system injury. Mortality presently approaches 50%. Mechanical ventilation (CMV) with continuous positive airway pressure (CPAP) remains the mainstay of therapy. High peak inspiration (PIP) and mean airway (PAW) pressure in association with the delivery of large, conventional mechanical breaths are major determinants of complications. The efficacy of HFV was evaluated in this patient population (45 patients, mean age, 32.7 +/- 14.4 years; range, 11-75). CMV was provided with a time-cycled ventilator delivering 12-15 cc/kg tidal volume and a mechanical rate adjusted to provide a PaCO2 38-42 torr for patients previously eucapneic. CPAP was titrated to achieve a preselected endpoint of an intrapulmonary shunt of less than equal to 15%. FIO2 was maintained at or below 0.45 whenever possible. The Trauma Index Score for the group was 8.8 +/- 2.4. CMV yielded a mechanical rate of 6.3 +/- 3.2 and a CPAP of 13.9 +/- 8.5 cm H2O. High-frequency ventilation was provided by either a solenoid-based jet ventilator (HFJV) or a pneumatic cartridge high-frequency pulse generator (HFPG). Measured and calculated hemodynamic and pulmonary variables were obtained prior to and 20 minutes after transition to HFV. Thirty-three patients received HFJV; 12 patients received HFPG. Data were evaluated with a paired t-test. All patients on HFJV demonstrated improved CO2 elimination with the same hemodynamic profiles. Those on HFPG demonstrated comparable gas exchange and hemodynamic profiles with lower CPAP/PIP. Where measured, PAW was significantly lower with HFPG when compared with CMV.

The role of high-frequency ventilation in post-traumatic respiratory insufficiency.

Post-traumatic pulmonary insufficiency or the adult respiratory distress syndrome is not infrequently associated with multiple organ-system injury. Mortality presently approaches 50%. Mechanical ventilation (CMV) with continuous positive airway pressure (CPAP) remains the mainstay of therapy. High peak inspiration (PIP) and mean airway (PAW) pressure in association with the delivery of large, conventional mechanical breaths are major determinants of complications. The efficacy of HFV was evaluated in this patient population (45 patients, mean age, 32.7 +/- 14.4 years; range, 11-75). CMV was provided with a time-cycled ventilator delivering 12-15 cc/kg tidal volume and a mechanical rate adjusted to provide a PaCO2 38-42 torr for patients previously eucapneic. CPAP was titrated to achieve a preselected endpoint of an intrapulmonary shunt of less than equal to 15%. FIO2 was maintained at or below 0.45 whenever possible. The Trauma Index Score for the group was 8.8 +/- 2.4. CMV yielded a mechanical rate of 6.3 +/- 3.2 and a CPAP of 13.9 +/- 8.5 cm H2O. High-frequency ventilation was provided by either a solenoid-based jet ventilator (HFJV) or a pneumatic cartridge high-frequency pulse generator (HFPG). Measured and calculated hemodynamic and pulmonary variables were obtained prior to and 20 minutes after transition to HFV. Thirty-three patients received HFJV; 12 patients received HFPG. Data were evaluated with a paired t-test. All patients on HFJV demonstrated improved CO2 elimination with the same hemodynamic profiles. Those on HFPG demonstrated comparable gas exchange and hemodynamic profiles with lower CPAP/PIP. Where measured, PAW was significantly lower with HFPG when compared with CMV.

気流可視化用高圧高周波パルス発生装置の開発

気流可視化用高圧高周波パルス発生装置の開発

A high frequency pulse generator for injuring tissue within the Sandison-Clark rabbit ear chamber.

SUMMARYA radio‐frequency pulse generator capable of inflicting variable but reproducible thermal injuries on tissue within the Sandison‐Clark rabbit car chamber is described. A technique facilitating the production of very small injuries at any chosen site within the car chamber is outlined. Some of the applications for the technique are discussed.