Generation Of High-power Pulses Research Articles

Influence factors and improvement scheme on the breakdown behavior of pseudospark switch

Abstract High-power pulse generators are widely used in civil and military fields. The main switch directly determines the output characteristics of the high-power pulse generators, such as the voltage front time (tf). Pseudospark switches (PSS) show a promising future for middle voltage, high repetitive frequency pulse power applications. However, how to further improve the breakdown behavior without reducing its advantages is a challenging task. In this paper, the influence of operating parameters (anode voltage UA and gas pressure p) and structural parameter (number of cathode holes) on the breakdown behavior are investigated, the related mechanism are explained, and specific improvement schemes are proposed. It is found that the tf of the single channel PSS (SCPSS) decreased significantly with increasing p, but hardly varied with UA under moderate p. However, it is not a sound solution to increase the p excessively to reduce tf. Besides, increasing the number of cathode holes can obtain a shorter tf at low pressures (which implies superior repetition frequency performance). However, at 25 Pa, the jitter (which is defined as the standard deviation of tf in multiple tests) of the 2-channel PSS is larger than that of the SCPSS. And the jitter of the 4-channel and 8-channel PSS is also greater than 6 ns and 2 ns, respectively. Through experimental and simulation analyses, it can be explained as the stepwise penetration of the virtual anode and the non-simultaneous ignition of the channels. A scheme to increase the trigger energy (ε) has been adopted to improve the simultaneous ignition probability, while shortening tf and reducing jitter. After optimization, the good ignition probability of the 4-channel PSS has been improved to 82% and the jitter has been reduced to less than 1 ns at 25 Pa and 14.7 mJ.

A novel racetrack Blumlein pulse forming line.

Pulse forming lines (PFL) are widely applied in high-power pulsed power generators due to their high energy density and great ability with square waveform modulation. However, the three-cylinder coaxial Blumlein line (tPFL), a commonly used PFL structure, has low energy efficiency due to the difference in impedance of the outer and inner lines. In order to increase the outer line impedance and improve the output waveform of the PFL, a racetrack Blumlein pulse forming line (r-B PFL), formed by two inner cylinders, two middle cylinders, and one outer cylinder that resembles a runway shape, is proposed in this paper. The glycerin energy storage technology and the spiral line technology were applied in the PFL. Moreover, the r-B PFL was tested experimentally after its construction, yielding a satisfactory result. The PFL structure in which multiple middle cylinders share the same outer cylinder achieves a higher outer line impedance, leading to a high energy efficiency of the PFL, which contributes to the PFL development trend toward compactness and miniaturization.

Wavelength scaling and multicolor operation of a plasma-driven attosecond x-ray source via harmonic generation

The generation of high-power coherent soft x-ray pulses of sub-100 as duration and 10 nm wavelength using beams from a GeV energy plasma wakefield accelerator has been recently investigated in Emma []. As a future upgrade to this concept, this contribution investigates scaling to shorter x-ray wavelengths by cascading undulators tuned to higher harmonics of the fundamental. We present two simulation studies for plasma-driven attosecond harmonic generation schemes with final photon wavelengths of 2 and 0.40 nm. We demonstrate in these schemes that using undulators with retuned fundamental frequencies can produce GW-scale pulses of sub-nm radiation with tens of attosecond-scale pulse lengths, an order of magnitude shorter than current state-of-the-art attosecond x-ray free electron lasers (XFELs). This multipulse multicolor operation will be broadly applicable to attosecond pump-probe experiments. Published by the American Physical Society 2024

Transistor Generators of High-Power Rectangular Pulses with Submicrosecond Duration

Transistor Generators of High-Power Rectangular Pulses with Submicrosecond Duration

Shaped Charge Liner Collapse and Jet Formation by Electromagnetic Loading on High Pulsed Power Generator

Shaped Charge Liner Collapse and Jet Formation by Electromagnetic Loading on High Pulsed Power Generator

Study on a novel shielded double-winding Rogowski coil for measurement of nano-second current pulses

A novel shielded double-winding Rogowski coil for measurement of nanosecond current pulses is studied. Theoretic analysis of the proposed coil is carried out, and the attenuation factor(reciprocal of the sensitivity) of the Rogowski coil is acquired. It is found that The proposed coil has an advantage on reducing the interference caused by annular displacement current due to the mirror-symmetry structure. A double-winding coil is developed for discharge current pulse of the high power pulse generator. A compact connector in which sampling resistor with resistance as low as 11.3 Ω could be integrated is also developed. According to calibration of the proposed coil, the calibration attenuation factor conforms to the theoretic result. The proposed coil is utilized for measurement of discharge current pulse of the pulse generator. The test result shows that the proposed coil responds well for rectangular pulses with front times of 4.3 ns.

PD28-04 ADVANCED BURST WAVE LITHOTRIPSY FOR HUMAN TRIALS

You have accessJournal of UrologyCME1 Apr 2023PD28-04 ADVANCED BURST WAVE LITHOTRIPSY FOR HUMAN TRIALS Arturo Holmes, Ekaterina Kuznetsova, Shivani Ramesh, Adam D. Maxwell, Ga Won Kim, John Kucewicz, Bryan W. Cunitz, Wayne Kreider, Barbrina Dunmire, Michael R. Bailey, Mathew D. Sorensen, and Jonathan D. Harper Arturo HolmesArturo Holmes More articles by this author , Ekaterina KuznetsovaEkaterina Kuznetsova More articles by this author , Shivani RameshShivani Ramesh More articles by this author , Adam D. MaxwellAdam D. Maxwell More articles by this author , Ga Won KimGa Won Kim More articles by this author , John KucewiczJohn Kucewicz More articles by this author , Bryan W. CunitzBryan W. Cunitz More articles by this author , Wayne KreiderWayne Kreider More articles by this author , Barbrina DunmireBarbrina Dunmire More articles by this author , Michael R. BaileyMichael R. Bailey More articles by this author , Mathew D. SorensenMathew D. Sorensen More articles by this author , and Jonathan D. HarperJonathan D. Harper More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003313.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The first in human trials of burst wave lithotripsy (BWL) demonstrated consistent fragmentation of upper tract stones with no or mild hematuria. However, for a randomized, controlled trial of treating 2-7 mm stones we wanted improved image resolution to not miss any fragments and ability to break stones to<1 mm at skin to stone depths of 4-10 cm on ultrasound. The system was redesigned and tested to add these improvements. METHODS: A new ultrasound platform for imaging, ultrasonic propulsion, and BWL was designed and constructed (‘Propulse2’). The imaging employed high-bandwidth phased array probes and Verasonics Vantage imaging engine. Resolution changes were compared against existing devices in a standard imaging phantom. Longer focus therapy transducers were designed. Additionally, the transducers operate at frequencies between 350-800 kHz. A high-power pulse generator was developed to achieve pressure at greater depths, produce longer duration pulses, and enable interleaving BWL with ultrasonic propulsion pulses and accelerate fragmentation. To test the therapeutic capabilities, rehydrated 2-7 mm calcium oxalate monohydrate stones were sonicated with each transducer and frequency in a calyx phantom in 2.5-minute intervals for 20 minutes. After each interval, the fragments were weighed and sieved to 1 and 2 mm, then returned to the phantom. Burst cycle durations between 5 to 160 cycles were tested with and without interleaved pulses and depths 4-10 cm all at focal peak negative pressures of 7 MPa. RESULTS: Imaging contrast (signal to noise ratio) with the old and new systems was 1.62 and 3.45 at 6 cm depth and 1.07 and 1.75 at 10 cm depth. Lateral resolution was improved by a factor of 2.1 at 6 cm and 2.5 at 10 cm. Targeting accuracy was measured to be within 1 mm for all transducers. On average for all stones and conditions, 81% and 75% of the stone mass was comminuted to<2 mm and < 1mm fragments respectively in 20 minutes (Figure 1A). Subanalysis of fragmentation to<2 mm fragments showed fewer than 20 cycles were less effective even with increased pulse repetition rate to equalize energy (Figure 1B). CONCLUSIONS: The system demonstrated over twice the imaging contrast and resolution and capability to fragment stones more finely over a 4-10 cm depth. Propulse2 has been approved for human trials (ClinicalTrials.gov number, NCT04796792). Source of Funding: Work supported by NIDDK P01 DK043881. © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e819 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Arturo Holmes More articles by this author Ekaterina Kuznetsova More articles by this author Shivani Ramesh More articles by this author Adam D. Maxwell More articles by this author Ga Won Kim More articles by this author John Kucewicz More articles by this author Bryan W. Cunitz More articles by this author Wayne Kreider More articles by this author Barbrina Dunmire More articles by this author Michael R. Bailey More articles by this author Mathew D. Sorensen More articles by this author Jonathan D. Harper More articles by this author Expand All Advertisement PDF downloadLoading ...

100-GHz ultra-short high-peak-power colliding-pulse mode-locked laser with asymmetric coating.

By using colliding-pulse mode-locking (CPM) configuration with asymmetric cladding layer and coating, 1.5-µm AlGaInAs/InP multiple quantum well (MQW) CPM lasers with high-power and ultra-short pulse generation capability at a repetition rate of 100 GHz are reported. The laser adopts a high-power epitaxial design, with four pairs of MQWs and an asymmetrical dilute waveguide cladding layer to reduce the internal loss, maintaining good thermal conductivity while increasing the saturation energy of the gain region. The asymmetric coating is introduced, as compared to conventional CPM laser with symmetric reflectivity, to further increase the output power and shorten the pulse width. With a high reflection (HR) coating of 95% on one facet and another facet as cleaved, 100-GHz sub-picosecond optical pulses with peak power on a Watt level are demonstrated. Two mode-locking states, the pure CPM state and the partial CPM state, are investigated. Pedestal-free optical pulses are obtained for both states. For the pure CPM state, a pulse width of 564 fs, an average power of 59 mW, a peak power of 1.02 W, and an intermediate mode suppression ratio over 40 dB are demonstrated. For the partial CPM state, a pulse width of 298 fs is demonstrated.

Low-Noise Femtosecond SESAM Modelocked Diode-Pumped Cr:ZnS Oscillator

Cr-doped ZnS and ZnSe are excellent gain mediums for high power and broadband ultrashort pulse generation in the 2 – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3~\mu \text{m}$ </tex-math></inline-formula> wavelength range. SESAM modelocked Cr:ZnS oscillators have the advantage of reliable, self-starting passive modelocking. We present a diode-pumped, SESAM modelocked Cr:ZnS oscillator delivering ultrashort pulses of 189 fs at 550 mW average output power with a repetition rate of 435 MHz with low relative intensity noise (RIN) and timing jitter. We measured an integrated RIN of 0.05% within a frequency span of [10 Hz, 5 MHz] dominated by the 1560-nm pump diode, and a very low integrated timing jitter of 10.9 fs [2 kHz, 10 MHz]. This type of laser source benefits not only from very low noise but also from reduced complexity and cost due to direct diode pumping, which is suitable for many applications such as spectroscopy, ranging, and frequency conversion.

Partial Discharge Characteristics of Biaxially Oriented Polypropylene Film Under Nanosecond Pulse Voltage With High Rise Rate

Film capacitors are used as the key energy storage device for high-power pulse generators, and partial discharge (PD) is an important factor leading to insulation degradation and the failure of film capacitors. To accurately evaluate the effect of the rise rate on PD under nanosecond pulse voltage, experiments on the PD characteristics of biaxially oriented polypropylene (BOPP) films under high rise rate (18.3–140 V/ns) nanosecond pulse voltages were carried out. The PDs were mostly concentrated in the rising and falling phases of the nanosecond pulse. Moreover, the repetitive PD inception voltage (RPDIV) first increased and then remained unchanged as the rise time increased, and the PD amplitude and the number of discharges in the rising phase of the nanosecond pulse increased as the rise rate increased, while the discharge time lag decreased gradually. The PD amplitude, the number of discharges, and the discharge time lag in the falling phase of the nanosecond pulse all increased as the rise rate increased. In addition, when the rise rate was less than 50 V/ns, the PD statistical characteristics changed rapidly as the rise rate increased, and when the rise rate was greater than 50 V/ns, the PD statistical characteristics gradually changed more slowly as the rise rate increased.

Generation of high-power Q-switched pulses based on arc-shaped fiber and tapered fiber with Sb2Te3 in erbium/ytterbium doped fiber laser

This study illustrates the capability of antimony telluride (Sb2Te3) utilized as a saturable absorber (SA) for generating high-power Q-switching in the 1.5-µm region. First, the exfoliated Sb2Te3 solution was fabricated using the liquid phase exfoliation (LPE) technique and integrated onto a D-shaped and tapered fiber, respectively. Then, the SA was inserted into the erbium-ytterbium-doped fiber laser (EYDFL) cavity. For the arc-shaped fiber-based SA, the passive Q-switched pulses were obtained at 1.34 W threshold pump power, whereas the tapered fiber-based SA has a threshold of 0.4 W. As a result, the highest average Q-switched optical power generated by Sb2Te3-coated arc-shaped fiber was 140.2 mW with a repetition rate ranging from 35.7 to 91.3 kHz and pulse widths from 2.51 to 1.65 µs. On the other hand, the tapered fiber coated with Sb2Te3 could only generate a maximum average output power of 21.7mW. Moreover, this SA generates Q-switched pulses with a repetition rate ranging from 5.76 kHz to 39.2 kHz and a pulse width from 5.14 to 16.34 µs. This indicates that Sb2Te3 can serve its purpose as an SA to produce high-power Q-switched pulses without degradation.

A novel compact solid-state high power pulse generator based on magnetic switch and square waveform pulse transformer.

The high power pulse generators have been widely used in high power microwave generation and plasma physics research. In this paper, a novel compact solid-state high power pulse generator is studied, numerically and experimentally. The generator is mainly composed of the primary energy supply, the magnetic pulse compressor, the Blumlein type low-impedance pulse forming network, and the square waveform pulse transformer. Especially, design considerations for a solid-state high power pulse generator are proposed. Experimental results show that pulses with a peak power of 2 GW, a duration of 150ns, and a repetitive rate of 10Hz are continuously achieved on a dummy load. The dimension is Φ60 × 210cm2, and the average power density reaches ∼5 W/L. Experimental results show reasonable agreement with numerical analysis.

Systems and technologies based on nonlinear transmission lines with ferrite (Review)

Nonlinear transmission lines with ferrite have been actively developed and studied for about two decades. At the same time, the first works on this topic date back to the middle of the last century. Nonlinear transmission lines with ferrite find their application in various problems of electrophysics, with the greatest application being found in the problems of pulse sharpening, as delay lines and generators of high-power pulses of microwave radiation. The main scientific and technical results of the development of technologies of nonlinear transmission lines with ferrite are presented in chronological order, starting from lines for sharpening the fronts of voltage pulses, ending with multichannel microwave sources based on them. Keywords: high power microwaves, ferromagnetic materials, pulsed power, electromagnetic shock waves.

Системы и технологии на основе нелинейных передающих линий с ферритом (обзор)

Nonlinear transmission lines with ferrite have been actively developed and studied for about two decades. At the same time, the first works on this topic date back to the middle of the last century. Nonlinear transmission lines with ferrite find their application in various problems of electrophysics, with the greatest application being found in the problems of pulse sharpening, as delay lines and generators of high-power pulses of microwave radiation. The main scientific and technical results of the development of technologies of nonlinear transmission lines with ferrite are presented in chronological order, starting from lines for sharpening the fronts of voltage pulses, ending with multichannel microwave sources based on them.

Ultrafast Buildup Dynamics of Terahertz Pulse Generation in Mode-Locked Quantum Cascade Lasers

Ultrashort terahertz pulse generation is essential for a range of proven terahertz applications, from time-resolved spectroscopy of fundamental excitations to nondestructive testing and imaging. Recently, it has been shown that semiconductor-based terahertz quantum cascade lasers (QCLs) can be used to generate pulses as short as a few picoseconds through active mode locking. However, further progress for subpicosecond and high peak power pulse generation is hampered by poor knowledge on how the electric field actually forms in these lasers. Here, we theoretically and experimentally show the amplitude- and phase-resolved buildup of pulse generation through active mode locking, from initiation of pulse generation to the nanosecond steady state. The experimental results, using an ultrafast coherent seeding technique to probe the laser from femtosecond to nanosecond time scales, are in full agreement with the theoretical calculations based on a theoretical model using multimode reduced rate equations. In particular, we show that the electric field buildup to achieve short pulse operation is extremely fast, requiring only a few photon round trips, owing to the ultrafast gain dynamics of the lasers. Further, this shows a gain recovery time of the order of a few picoseconds, an order of magnitude smaller than the photon round-trip time, highlighting that terahertz QCLs are categorically class-A lasers. This demonstration marks an important formulism for future progress towards exploring the ultrafast pulse generation buildup dynamics of these complex semiconductor lasers.

High-Power Mode-Locked Fiber Laser Using Lead Sulfide Quantum Dots Saturable Absorber

The discovery of different types of nanomaterials including the one-dimensional and two-dimensional materials used as saturable absorbers (SAs) in the applications of ultrafast lasers in recent years increases the ultrafast laser design flexibility and boosts the laser performances. A major research avenue is to explore the potential of nanomaterials for further enhancing the performances of ultrafast lasers in terms of pulse power. To this aim, in this study, using a hot-injection method and drop-coating technology, a fiber-based lead sulfide quantum dot (PbS QD) is synthesized, and its potential as a SA for the generation of higher-power pulses is demonstrated in an erbium-doped fiber laser (EDFL). Experimental results show that the optical damage threshold of the SA is greater than 152.6 mJ/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and the modulation depth is up to 29.5%. The implementation of the PbS QD as a SA placed in an EDFL enables the laser to yield 2.84 ps ultrashort pulses with an average output power of 59.4 mW at a repetition rate of 6.97 MHz. To the best of our knowledge, it is the highest average output power obtained in ultrafast fiber lasers mode-locked by zero-dimensional QD materials. The results suggest the great potential of PbS QDs in the application that requires the generation of high-power pulses in ultrafast lasers.

Simple method for broadband amplification in a polarizing-maintained Yb fiber amplifier with a narrow bandpass filter.

We have demonstrated a simple method for achieving broadband amplification and short-pulse generation in a polarizing maintained (PM) Yb fiber amplifier with the implementation of a narrow bandpass filter (NBF). By using an NBF with a spectral bandwidth of 3.3 nm at a wavelength of 1036 nm before the PM Yb amplifier, the spectral bandwidth was extended by self-phase modulation (SPM) in the PM YDF amplifier. The recompressed pulse duration of 125 fs obtained with the NBF was nearly three times shorter than that (350 fs) achieved without the NBF, and therefore the peak intensity of 0.35 MW with the NBF was over two times greater in comparison with that (0.16 MW) obtained without the NBF. We believe that this simple method is useful for developing an all-fiber laser system for high-power short pulse generation.

A Compact Repetitive High-Power Pulse Generator Based on Air-Cored Pulse Transformer

A Compact Repetitive High-Power Pulse Generator Based on Air-Cored Pulse Transformer

Spectral purification of single-frequency Stokes pulses in doubly resonant integrated diamond resonators

Pulsed spectrally pure light is required for applications in high-resolution spectroscopy, optical coherent communications, and quantum technologies. In this work, we report on the efficient generation of high peak power, single-frequency, and tunable nanosecond pulses utilizing stimulated scattering, with an increased spectral brightness by exploiting double resonances in an integrated diamond Raman resonator. The device is based on a miniature monolithic Fabry–Perot design pumped by a milliwatt-class average power Q-switched single-frequency pulsed laser at 532 nm. Our device was capable of enhancing the peak spectral brightness by greater than three times compared with conventional singly resonant diamond Raman lasers by tuning the effective resonator length at pump and Stokes wavelengths simultaneously. Our results facilitate the integration of pulsed and power scalable single frequency sources into hybrid photonic integrated platforms with a broad range of applications.

Generation of high-power breathing pulses based on Peregrine soliton by using saturable absorber

We obtain high-power breathing pulses based on Peregrine soliton by using a saturable absorber. Due to the presence of background wave, Peregrine soliton cannot transmit stably in optical fiber. To obtain high-power breathing pulses, we use a saturable absorber to eliminate the background wave. The results show that the high-power breathing pulse with periodic oscillation can be generated from Peregrine soliton by the saturable absorber with appropriate modulation depth. And the high-power breathing pulses can transmit long-distance in optical fiber. The evolution behavior of breathing pulses can be controlled by the initial input pulse and the length of erbium-doped fiber. And the breathing pulse has strong anti-noise ability.