Статті в журналах: "Pulse operation mode"

1

Godun, D. V., S. V. Bordusau, and G. P. Budzko. "Output Current Control System of a High Voltage Electric Pulse Generator for Plasma Excitation." PLASMA PHYSICS AND TECHNOLOGY 6, no. 1 (2019): 7–9. http://dx.doi.org/10.14311/ppt.2019.1.7.

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A control and pulse discharge current limiting system integrated into an AC/DC converter and pulse modulator of a high voltage pulse generator have been developed. The peculiarity of such system\textquotesingle s operation is the stabilization of the power supplied to the discharge and the correction of the width of output electric pulses towards decrease upon reaching the specified pulsed current amplitude value. The system enables the pulse generator to work in the modes close to the ``short circuited load'' mode. In this case the driving module of a composite IGBT key performs the correction of the working pulse width and blocks the pulse generator operation if needed. The suggested circuit design solutions allow using the generator in a wide range of electric plasma-forming parameters' modes and working with various types of vacuum gas discharge systems.

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2

Zhuravlev, I. M., and A. V. Osipov. "Resonant solar cell energy converter in the power supply system for small spacecraft." Proceedings of Tomsk State University of Control Systems and Radioelectronics 23, no. 3 (September 25, 2020): 81–85. http://dx.doi.org/10.21293/1818-0442-2020-23-3-81-85.

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The operation of a solar cell resonant converter at operating modes in the power supply system of a small spacecraft is investigated. The resonant converter with pulse-code regulation simulation model has been developed, and the operation point by stabilizing charge current mode and stabilizing output voltage mode is considered. The converter regulating characteristics in various operating modes are obtained.

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3

Takahashi, Sadayuki, Takeshi Yano, Shinichi Hori, and Eiichi Sato. "Pulse Mode Operation for Piezoelectric Ceramic Actuator." Japanese Journal of Applied Physics 26, S2 (January 1, 1987): 180. http://dx.doi.org/10.7567/jjaps.26s2.180.

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4

Zhang, Liqiang, Zhiyong Pan, Zhuang Zhuo, and Yunzheng Wang. "Three Multiple-Pulse Operation States of an All-Normal-Dispersion Dissipative Soliton Fiber Laser." International Journal of Optics 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/169379.

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Multiple-pulse operation states of an all-normal-dispersion Yb-doped double-clad dissipative soliton fiber laser are investigated in this paper. The proposed laser can deliver harmonic mode-locked pulses, bound states of dissipative solitons, and dual-wavelength dual-pulses. Stable second-harmonic and third-harmonic mode-locked pulse trains are obtained with the output power of 1.39 W and 1.46 W, respectively, and the corresponding single pulse energies are 12.1 nJ and 8.5 nJ. With the adjustment of pump power and the wave plates, the fiber laser generates bound states of two or three dissipative solitons. Moreover, a dual-wavelength dual-pulse state is presented, where the output pulses from the nonlinear polarization rotation rejection port consists of the leading and trailing edges of the pulses circulating in the cavity.

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5

Gribacheva, V., and S. Shcherbakov. "THE COOLING SYSTEM OF THE PERIODIC PULSED REACTOR." PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. SERIES: NUCLEAR AND REACTOR CONSTANTS 2021, no. 2 (June 26, 2021): 256–67. http://dx.doi.org/10.55176/2414-1038-2021-2-256-267.

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The paper proposes the configuration and composition equipment of the cooling system of the designed periodic pulsed reactor (PPR) of high power. The special features of the PPR are a small flow section, a large heating of the coolant in the power pulse and the impossibility of useful use of thermal energy in the periodic mode of operation. Liquid lithium is proposed as a coolant and heat is discharged through air heat exchangers (AHE). The goal was to achieve compactness and low power consumption, the ability to work with frequent stops and optimize the operation of equipment in pulse modes. For this purpose, high-temperature AHE with a small heat exchange surface and forced air cooling are used, the circulation circuit is divided into two parts - the reactor circuit and the AHE circuit with two circulation pumps and a common drain tank. The separation of the circuit allows to independently perform the operations of starting, stopping and heating the circuits in a periodic mode. The drain tank limits the composition of the equipment exposed to temperature pulses. Numerical studies of the temperature regime of the coolant in the equipment of the PDR cooling system are carried out. The calculations were performed using the TURBOFLOW code in two-dimensional terms for all the main elements of the equipment. Quasi-stationary (nominal and partial power levels) and pulse modes of operation are considered. Calculated characteristics for forced and natural air circulation are obtained. The limits of the air circulation modes under the conditions of non-freezing of the coolant are determined. The obtained values of the maximum temperatures of the coolant: in the pulsed mode is 750 °C, in the quasi-stationary mode - 490 °C with an average power of 15 MW, air flow of 150 m3/s and the size of the AHE in the plan of 5×5 m, 100 panels of 1.08×0.025×5 m.

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6

Cauffman, Stephen, Monica Blank, Philipp Borchard, and Kevin Felch. "Adaptation of a Dual-Frequency 104/140 GHz Gyrotron for Operation at 175 GHz." EPJ Web of Conferences 203 (2019): 04004. http://dx.doi.org/10.1051/epjconf/201920304004.

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A dual-frequency gyrotron capable of operation in the TE28,7 cavity interaction mode at 140 GHz, or in the TE22,5 mode at 104 GHz, has been developed for use in electron cyclotron heating in the W7-X stellarator at IPP Greifswald. The gyrotron incorporates an internal converter design that has been numerically optimized to convert either of the two operating modes into a high-quality Gaussian output beam. During short-pulse factory testing, the gyrotron produced 900 kW at 140 GHz, and 520 kW at 104 GHz. After delivery to IPP, the gyrotron was conditioned to long-pulse operation at 140 GHz, demonstrating 30-minute pulses at several power levels up to 811 kW, and producing ten consecutive ten-minute pulses at 811 kW as well. After long-pulse capabilities were demonstrated at 140 GHz, IPP requested an analysis of the feasibility of operating the gyrotron (without internal modification) in an additional mode with a frequency near 175 GHz. Several potential interaction modes were evaluated to determine the required operating parameters for excitation of these modes, and to assess the expected interaction efficiency, output power, internal diffraction losses, and output beam quality. The most promising modes appear to be the TE33,9 (173 GHz) and the TE34,9 (176 GHz), which should generate 400-500 kW of RF in a suitable magnet capable of producing the necessary 7.1 T field required for operation at these higher frequencies. Because the existing gyrotron’s internal converter was not optimized for these modes, however, internal losses are expected to be higher than usual (up to 7%), and the output beam pattern will require external phase-correction in order to produce a Gaussian beam. A feasibility analysis for such external phase correction has been performed, demonstrating that a high-quality beam can be recovered using numerically synthesized external phase-correcting mirror surfaces.

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7

Pushkarev, A. I., Y. I. Isakova, and I. P. Khaylov. "Stabilization of ion beam generation in a diode with self-magnetic insulation in double-pulse mode." Laser and Particle Beams 33, no. 2 (April 17, 2015): 283–91. http://dx.doi.org/10.1017/s0263034615000385.

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AbstractThe paper presents the results of statistical studies of ion beam generation in different geometry diodes with explosive emission cathode in a mode of self-magnetic insulation. The experiments were carried out using the TEMP-4M pulsed ion beam accelerator during its operation in both unipolar pulse mode (100 ns, 250–300 kV) and bipolar-pulse mode with the first negative (300–600 ns, 100–150 kV) followed by a second positive (120 ns, 250–300 kV) pulse. It is found that the standard deviation of the total energy and energy density of the beam does not exceed 10–11%, while the same shot-to-shot variation in ion current density was found to be 20–30%. The mechanism of the energy density stabilization from pulse to pulse may be associated with the charge exchange between accelerated ions and stationary molecules and formation of accelerated neutrals. We observed a high correlation between the energy density (or total beam energy) and the duration of the first voltage pulse. We performed analysis of Blumlein statistical performance when the Blumlein was terminated with a resistive load and with a self-magnetically insulated ion diode. A characteristic feature of Blumlein operation in the double-pulse mode is an excellent reproducibility of breakdown of the preliminary spark gap, the variation in breakdown voltage is <2%. At the same time, the shot-to-shot variation in the breakdown voltage of the main spark gap in both bipolar- and unipolar pulse mode is 3–4 times higher than that for the preliminary spark gap. To improve the statistical performance of the main spark gap we used the first voltage pulse at the output of Blumlein to trigger the main spark gap. The new trigatron-type regime of the main spark gap operation showed a better reproducibility of the first pulse duration, with the time jitter not exceeding 10 ns in a set of 50 pulses.

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8

Sun, Yanwen, Franz-Josef Decker, James Turner, Sanghoon Song, Aymeric Robert, and Diling Zhu. "Pulse intensity characterization of the LCLS nanosecond double-bunch mode of operation." Journal of Synchrotron Radiation 25, no. 3 (March 27, 2018): 642–49. http://dx.doi.org/10.1107/s160057751800348x.

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The recent demonstration of the `nanosecond double-bunch' operation mode,i.e.two X-ray pulses separated in time between 0.35 and hundreds of nanoseconds and by increments of 0.35 ns, offers new opportunities to investigate ultrafast dynamics in diverse systems of interest. However, in order to reach its full potential, this mode of operation requires the precise characterization of the intensity of each X-ray pulse within each pulse pair for any time separation. Here, a transmissive single-shot diagnostic that achieves this goal for time separations larger than 0.7 ns with a precision better than 5% is presented. It also provides real-time monitoring feedback to help tune the accelerator parameters to deliver double pulse intensity distributions optimized for specific experimental goals.

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9

Xu, Nannan, Pengfei Ma, Shenggui Fu, Xinxin Shang, Shouzhen Jiang, Shuyun Wang, Dengwang Li, and Huanian Zhang. "Tellurene-based saturable absorber to demonstrate large-energy dissipative soliton and noise-like pulse generations." Nanophotonics 9, no. 9 (February 12, 2020): 2783–95. http://dx.doi.org/10.1515/nanoph-2019-0545.

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AbstractTwo-dimensional layered monoelemental materials (Xenes) with excellent optoelectronic properties have various property-related applications, such as energy, biomedicine, and optoelectronic devices. Xenes also show excellent performance in acting as saturable absorbers (SAs) for obtaining ultrafast laser operations. Few-layer tellurene as a typical Xenens exhibits distinct optoelectronic properties and promising practical application potential, and its nonlinear optical absorption characteristics and related ultrafast modulation applications have been investigated preliminarily. However, tellurene-based SAs to demonstrate large-energy mode-locked operations, which have special applications in industrial and scientific research areas, are seldom studied. In this work, we focus on the preparation of tellurene-based SAs and explore its applications in demonstrating large-energy mode-locked operations [dissipative soliton (DS) and noise-like pulses (NLP)]. For DS operation, the maximum average output power, pulse width, and largest pulse energy are 23.61 mW, 5.87 ps, and 1.94 nJ, respectively. NLP operation with a recorded average output power of 106.6 mW and a pulse energy of 8.76 nJ is also generated, which shows significant enhancement in comparison to previously reported Xenes-based works. Our contribution reveals the great potential and capacity of tellurene-based SAs in obtaining large-energy pulse operations and further promotes the explorative investigation of Xenes-based optoelectronic devices.

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10

Popova, L. I., S. K. Andreev, V. K. Gueorguiev, and N. D. Stoyanov. "Pulse mode of operation of diode humidity sensors." Sensors and Actuators B: Chemical 37, no. 1-2 (November 1996): 1–5. http://dx.doi.org/10.1016/s0925-4005(97)80065-2.

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11

Andreev, V. V., A. V. Kedrov, B. G. Levakov, O. A. Mingazov, S. G. Porubov, and S. V. Shugaev. "IGRIK reactor operation in a two-pulse mode." Atomic Energy 102, no. 3 (March 2007): 174–80. http://dx.doi.org/10.1007/s10512-007-0026-y.

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12

Ivanov, Pavel A., Oleg Kon'kov, Tatyana Samsonova, Alexander Potapov, and Igor Grekhov. "Electrical Performance of 4H-SiC Based Drift Step Recovery Diodes." Materials Science Forum 858 (May 2016): 761–64. http://dx.doi.org/10.4028/www.scientific.net/msf.858.761.

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Mesa-epitaxial 4H-SiC p+-p-no-n+-diodes were fabricated from commercial epitaxial wafers. Reverse recovery characteristics of the diodes were measured in pulse regimes to be relevant to operation of drift step recovery diodes (DSRDs) [1]. When injecting the minority carriers by forward current pulse followed by applying a reverse voltage pulse, the diodes are able to break the reverse current in a subnanosecond time (DSRD-mode). Different regimes of diode operation in DSRD-mode are investigated such as variable reverse voltage amplitude, forward current amplitude and duration, time delay between forward and reverse pulses.

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13

Sojka, Lukasz, Lukasz Pajewski, Samir Lamrini, Mark Farries, Trevor M. Benson, Angela B. Seddon, and Slawomir Sujecki. "Experimental Investigation of Actively Q-Switched Er3+:ZBLAN Fiber Laser Operating at around 2.8 µm." Sensors 20, no. 16 (August 18, 2020): 4642. http://dx.doi.org/10.3390/s20164642.

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A diode-pumped Q-switched Er3+:ZBLAN double-clad, single-transverse mode fiber laser is practically realized. The Q-switched laser characteristics as a function of pump power, repetition rate, and fiber length are experimentally investigated. The results obtained show that the Q-switched operation with 46 µJ pulse energy, 56 ns long pulses, and 0.821 kW peak power is achieved at a pulse repetition rate of 10 kHz. To the best of our knowledge, this is the highest-ever demonstrated peak power emitted from an actively Q-switched, single-transverse mode Er3+:ZBLAN fiber laser operating near 2.8 µm.

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14

Mat Salim, M. A., M. A. Ismail, M. Z. A. Razak, Saaidal R. Azzuhri, H. Bakhtiar, and N. Bidin. "Generation of stable mode-locked fiber laser based MWCNTs in 1.5-µm waveband." Journal of Physics: Conference Series 2075, no. 1 (October 1, 2021): 012008. http://dx.doi.org/10.1088/1742-6596/2075/1/012008.

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Abstract Pulses fiber laser had been successfully generated by using multi-wall carbon nanotubes thin film saturable absorber at room temperature. The saturable absorber is incorporated into a ring laser cavity. A stable Kelly sidebands mode-locked pulse spectrum with 1561.3 nm wavelength at the pump power of 86.8 mW. The repetition rate and pulse width of 12.3 MHz and 0.51 picosecond, respectively. A stable operation is observed for an hour at room temperature. These simple and reliable system features offer interesting research study especially in mode-locked pulse generation at 1.5 μm waveband.

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15

Bily, Tomas, and Ondrej Huml. "Characterization of neutron emission during pulse mode of low output electronic neutron generator." EPJ Web of Conferences 253 (2021): 04003. http://dx.doi.org/10.1051/epjconf/202125304003.

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The paper deals with the characterization of the neutron output during operation the neutron generator in the pulsing mode. The characterization is performed by a cadmium covered He-3 detector. First, the adequacy of a cadmium covered He-3 detector to study the pulsed mode operation of neutron generator is assessed using Monte Carlo simulations in MCNP6 code. Second, the pulsing mode operation of the D-D P-385 Thermo Fisher Scientific neutron generator with a maximal neutron output of 7 x 106 n/s is studied. The study shows the dependence of neutron emission and pulse shapes on the frequency, duty factor, high voltage and beam current.

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16

Mohamed, M. M., T. Uchida, and S. Minami. "A Pulse-Operated Microwave-Induced Plasma Source." Applied Spectroscopy 43, no. 1 (January 1989): 129–34. http://dx.doi.org/10.1366/0003702894202058.

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A new pulse-operated microwave-induced plasma (MIP) source is described. To avoid operational difficulties of the MIP due to Joule heating and to obtain spectral emission lines of high peak intensities, one energizes the MIP source with a TM010 cavity with a microwave pulse of large peak power and short duration, which is superposed on a low-bias dc microwave. A peak power of 400 W, which is two times the maximum output ratings of a magnetron under a normal dc operation, can be generated by applying a −500 V pulse to the cathode of the magnetron operating under the bias mode. The pulsed-MIP requires no special cooling system since the mean power remains low during the entire operation. Some of the considerations taken into account in the design and construction of the microwave generator are presented. The electrical and spectral characteristics of the MIP source are also described in detail.

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17

Bostanjoglo, O., F. Heinricht, and F. Wünsch. "Performance of A Laser-Pulsed Thermal Electron Gun." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 124–25. http://dx.doi.org/10.1017/s0424820100179373.

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High-speed electron microscopy strongly demands a high-brightness electron gun in order to increase the number of image forming electrons. A few years ago, a laser-pulsed high-brightness electron gun was introduced. Fig.1 shows the experimental set-up, A standard triode system was supplemented with a Nd:YAG laser, focussing optics and a modified anode, which incorporates the laser deflection mirror. The frequency doubled laser pulse (τ =5 ns, λ = 532 nm) is focused through a window onto the tip of the tungsten hairpin emitter. The laser treated area (≈ 100 μm diameter) is heated well above the melting point, which results in a strong thermal electron emission. Due to rapid heat-up and fast cool-down of the tungsten surface short electron pulses with a duration of 20 ns and a maximum current of 20 mA at 80 kV are emitted. A destruction of the tungsten wire is avoided, too. Laser energies used for the generation of electron pulses are in the range of 100 μJ. Due to these minor modification, the DC operation of the electron gun is not disabled, which allows a convenient adjustment in the DC mode and then switching into the pulsed operation mode. Fig.2 shows a typical electron pulse emitted by the gun. Shorter electron pulses up to 5 ns can be generated by a beam blanking unit.

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18

Li, Zhaohan, Yongcheng Ji, Shu Yang, and Yuchun Chang. "A Dual-Mode High-Voltage High-Efficiency Peak-Current-Mode Asynchronous Buck Converter." Journal of Circuits, Systems and Computers 25, no. 11 (August 14, 2016): 1650136. http://dx.doi.org/10.1142/s021812661650136x.

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This paper proposes a high-voltage high-efficiency peak-current-mode asynchronous DC–DC step-down converter operating with dual operation modes. The asynchronous buck converter achieves higher efficiency in light load condition compared to synchronous buck converters. Furthermore, the proposed buck converter switches operation mode automatically from pulse-width modulation (PWM) mode to pulse-skipping mode (PSM). By reducing power MOS on-state resistance and optimizing rise/fall time of switches, the proposed buck converter also obtains high efficiency under heavy load condition. The maximum efficiency of the proposed buck converter is 92.9%, implemented with 0.35[Formula: see text][Formula: see text]m BCDMOS 2P3M process, and the total size is 1.1[Formula: see text] 1.2[Formula: see text]mm2. The input range and output range of the converter are 6–30 V, and ([Formula: see text]–3) V, respectively, with the maximum output current of 3 A. Moreover, its built-in current loop leads to good transient response characteristics. Therefore, it can be used widely in communication system and 12 V/24 V distributed power system.

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19

Wang, Ji, Wenwu Zhang, and Tianrun Zhang. "Passively Q-Switched and Mode-Locked Er3+-Doped Ring Fiber Laser with Pulse Width of Hundreds of Picoseconds." Photonics 8, no. 12 (December 8, 2021): 560. http://dx.doi.org/10.3390/photonics8120560.

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Greatly improving the energy of a single mode-locked pulse while ensuring the acquisition of the width of short pulses will contribute to the application of mode-locked pulse in basic research, such as precision machining. This report has investigated a Q-switched and mode-locked (QML) erbium doped ring fiber laser based on the nonlinear polarization rotation (NPR) technology and a mechanical Q-switched device. Without the working of the mechanical Q-switched device, the fiber laser exported the continuous-wave mode-locked (CWML) pulse, with a width of 212.5 ps, and a repetition frequency of 81.97 MHz. For the CWML operation, the maximum output average power is 25.7 mW, and the energy is only 0.31 nJ. For the QML operation, 18.03 mW average power is achieved at the Q-switching frequency of 100 Hz. The energy of the QML pulse is increased by over 1100 times to 360.6 nJ. The width of the QML pulse is 203.1 ps measured by an autocorrelation curve, with the time-band product (TBP) being 0.598. The power instability is 0.5% (RMS) and 0.7% (RMS), respectively, for CWML and QML operation within 120 min. Furthermore, the spectral signal-to-noise ratio is about 60 dB. For the QML operation, the power instability is 0.48% (RMS) within 60 s and 0.37% (RMS) within 10 s. After frequency stabilization, the frequency fluctuation is ±100 Hz in the long-term of 1200 s, with the frequency stability (FS) calculated to be 2.44 × 10−6. It indicates that the QML fiber laser has good power stability and frequency stability.

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20

Tikhomirov, S. A. "Femtosecond System with Pulse Pumping of Seed Laser and Amplifier by Using a Single Power Unit." Devices and Methods of Measurements 12, no. 1 (March 19, 2021): 23–29. http://dx.doi.org/10.21122/2220-9506-2021-12-1-23-29.

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For several decades development of methods for generating ultrashort pulses has been an independent urgent scientific and technical problem. There is a constant improvement both in the methods of such pulses receiving and in methods of their use. The aim of this work was to investigate the possibility of realizing the coordinated operation of two fundamentally different types of pump lasers for the femtosecond oscillator and amplifier based on one single-lamp laser head and to create on this basis a compact high-power femtosecond system with pulsed pumping and one power unit.The practical implementation of two types of pulsed lasers (nano- and picosecond ones operating, respectively, in Q-switch and modelock regime) on a single laser head with two active elements and one pump lamp is carried out. The required synchronization in time the pump pulse femtosecond amplifier formation and quasi-stationary region of generated pulses in the output radiation of a femtosecond Ti:sapphire is obtained.On this basis a compact, pulse pumped monoblock laser system has been developed that can generate femtosecond pulses with a duration of 50–150 fs with an energy up to 1 mJ and a high enough pulse repetition rate (up to 1 kHz which is determined by the type of laser head and pump unit used). In the developed laser system a compact scheme of a stretcher-compressor with a single common diffraction grating is used.Laser systems of this type characterized by a relatively low cost due to the use of a single power supply unit for simultaneous pumping of the amplifier and oscillator, as well as lower requirements for the quality of optical elements and usage conditions due to the pulse mode of operation, are quite practical and can be used both in scientific research in the field of ultra-high-speed kinetic spectroscopy and nonlinear optics, as well as in numerous technical applications, particular in the precision processing of materials, as optical simulators of the action of heavy charged particles in testing the radiation resistance of integrated circuits and electronic modules.

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21

Konovalova, V. S., R. S. Konovalov, and S. I. Konovalov. "STUDY OF PULSE MODE OF PIEZOELECTRIC TRANSDUCER FOR ECHOSCOPE." Issues of radio electronics, no. 2 (February 20, 2019): 50–57. http://dx.doi.org/10.21778/2218-5453-2019-2-50-57.

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The piezoelectric transducer of the echoscope intended for research of soft tissues of the person is considered. The active element of the transducer is a damped piezoceramic plate. As an exciting electric signal, an electric voltage pulse with a different number of half‑cycles at the natural frequency of the plate is selected. The pulse mode of the radiator operation is investigated. The amplitudes and durations of the probing acoustic signal are estimated depending on the duration of the exciting pulse. The dynamics of changes in the durations and amplitudes of the radiated acoustic pulses is studied. For various degrees of damping of the plate, the number of half‑cycles contained in the exciting signal, from which the emitter operates in a stationary mode, is determined. The obtained results can be used in the field of design and development of technology for manufacturing of broadband pulse piezoelectric transducers of ultrasonic medical echoscopes.

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22

Glotov, A. N., Yu V. Golubenko, V. A. Desyatskov, and A. V. Stepanov. "Certain Features of Interaction Between Laser Radiation and Metals." Herald of the Bauman Moscow State Technical University. Series Instrument Engineering, no. 1 (130) (February 2020): 15–32. http://dx.doi.org/10.18698/0236-3933-2020-1-15-32.

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The paper presents experimental investigation results concerning the problem of optimising the efficiency of interaction between laser radiation and metals. We used several types of Nd lasers featuring the desired combination of power, temporal and spatial radiation parameters as sources of the radiation required. To pump these lasers, we employed rectangular pulses at a periodicity eliminating effects characteristic of continuous-wave and pulsed laser operation modes. This limits the laser radiation parameters driving the interaction efficiency functions to strictly those parameters that match the single-pulse laser operation mode. Temporal radiation parameter variation involved measurements in the free-running and high-frequency Q-switching modes as well as adjusting pumping (lasing) pulse durations. Power parameter variation was implemented through altering radiation energy density over the irradiated surface. Spatial structure of the ablative radiation was varied by means of optical radiation transfer facilities and different laser emitters. The experimental investigation results allowed us to establish certain patterns concerning the interaction between laser radiation and metals as a function of radiation parameters listed

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23

Kobus, Zbigniew, Monika Krzywicka, Anna Pecyna, and Agnieszka Buczaj. "Process Efficiency and Energy Consumption during the Ultrasound-Assisted Extraction of Bioactive Substances from Hawthorn Berries." Energies 14, no. 22 (November 15, 2021): 7638. http://dx.doi.org/10.3390/en14227638.

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This study investigated the impact of sonication parameters on the efficiency of the extraction of bioactive substances from hawthorn berries. The ultrasonic treatment was performed in two modes: continuous and pulse. In the pulse mode, the samples were sonicated with the following processor settings: 1 s on-2 s off. The effective ultrasonic processor times were 5, 10, and 15 min, and the total extraction times were 15 min, 30 min, and 45 min. The content of total polyphenols and total anthocyanins was determined by a spectrophotometric method. We show that the operating mode of the processor affects extraction efficiency, energy consumption and unit energy inputs. Extraction supported by a pulsating ultrasonic field allowed saving from 20% to 51% of energy with a simultaneous higher efficiency of the process. In addition, we show that the unit energy consumption in the pulsed mode was about 40% to 68% lower than the energy consumption in the case of continuous operation.

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24

Komarov, A., F. Amrani, A. Dmitriev, K. Komarov, D. Meshcheriakov, and F. Sanchez. "Multiple-Pulse Operation and Bound States of Solitons in Passive Mode-Locked Fiber Lasers." International Journal of Optics 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/418469.

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We present results of our research on a multiple-pulse operation of passive mode-locked fiber lasers. The research has been performed on basis of numerical simulation. Multihysteresis dependence of both an intracavity energy and peak intensities of intracavity ultrashort pulses on pump power is found. It is shown that the change of a number of ultrashort pulses in a laser cavity can be realized by hard as well as soft regimes of an excitation and an annihilation of new solitons. Bound steady states of interacting solitons are studied for various mechanisms of nonlinear losses shaping ultrashort pulses. Possibility of coding of information on basis of soliton trains with various bonds between neighboring pulses is discussed. The role of dispersive wave emitted by solitons because of lumped intracavity elements in a formation of powerful soliton wings is analyzed. It is found that such powerful wings result in large bounding energies of interacting solitons in steady states. Various problems of a soliton interaction in passive mode-locked fiber lasers are discussed.

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25

Bock, Stefan, Franziska Marie Herrmann, Thomas Püschel, Uwe Helbig, René Gebhardt, Jakob Johannes Lötfering, Richard Pausch, et al. "Characterization of Accumulated B-Integral of Regenerative Amplifier Based CPA Systems." Crystals 10, no. 9 (September 22, 2020): 847. http://dx.doi.org/10.3390/cryst10090847.

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We report on a new approach to measure the accumulated B-integral in the regenerative and multipass amplifier stages of ultrashort-pulse high-power laser systems by B-integral-induced coupling between delayed test post-pulses and the main pulse. A numerical model for such non-linear pulse coupling is presented and compared to data taken at the high-power laser Draco with self-referenced spectral interferometry (SRSI). The dependence of the B-integral accumulated in the regenerative amplifier on its operation mode enables optimization strategies for extracted energy vs. collected B-integral. The technique presented here can, in principle, be applied to characterize any type of ultrashort pulse laser system and is essential for pre-pulse reduction.

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26

Афанасьєва, Ольга Валентинівна, Наталія Олексіївна Лалазарова та Олена Георгіївна Попова. "Нові технології лазерної поверхневої обробки". Aerospace technic and technology, № 2 (28 квітня 2021): 59–65. http://dx.doi.org/10.32620/aktt.2021.2.07.

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Subject and purpose. Currently, gas, solid-state, and fiber lasers are used to process materials in the aviation industry. For the thermal treatment of steels, gas CO2 lasers with a capacity of more than 1 kW used, which are reliable in operation but have high cost and low efficiency. There are no results on the use of low-power (up to 20 W) pulsed-mode lasers for surface hardening of steel products. The purpose of this work is to determine the modes of surface hardening of products from carbon and alloy steels using low-power solid-state pulsed YAG lasers. Methodology. For laser hardening, a 5 W solid-state YAG laser was used (diode pumping, radiation wavelength λ = 1,064 μm, pulse mode). The use of a nonlinear crystal made it possible to obtain UV radiation with λ = 0,355 μm (third harmonic). The following modes were investigated: processing with single pulses (duration 0,1...0,4 ms) and multi-pulse processing with short (30...70 ms) pulses. The scanning speed was 8...2 mm/s. The energy in the pulse was determined by the photoelectric method. Thermal hardening was performed on the following steels: У12, P6M5. The possibility of UV radiation hardening was evaluated on steel 20, 45, У12, and ШХ15. Findings. The optimum values of pulse duration for maximum hardness in laser hardening of the investigated steels. With multi-pulse treatment of steels, the pulse duration is shorter than with single-pulse treatment, the hardening intensity is higher, and the quality of the processed surface is better. Single-pulse and multi-pulse processing are accompanied by partial melting of the surface of steel products, which does not allow it to be used in cases where a high quality of the surface is required. Laser hardening of steel by ultraviolet radiation is not accompanied by melting. Conclusion. For surface hardening of products, where partial melting of the surface is possible, low-power lasers in pulse mode can be used. Laser hardening by ultraviolet radiation is a promising direction for thermal hardening of steels, which allows maintaining the original quality of the surface layer. Thermal hardening with low-power lasers can be effective for small-sized areas of the processed parts of the fuel equipment of aircraft engines, friction elements, and, especially, the tool is small.

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27

Ikeda, Ryosuke, Ken Kajiwara, Yasuhisa Oda, Koji Takahashi, and Keishi Sakamoto. "High-power and long-pulse operation of TE31,11 mode gyrotron." Fusion Engineering and Design 96-97 (October 2015): 482–87. http://dx.doi.org/10.1016/j.fusengdes.2015.05.016.

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28

Martins‐Filho, J. F., and C. N. Ironside. "Multiple colliding pulse mode‐locked operation of a semiconductor laser." Applied Physics Letters 65, no. 15 (October 10, 1994): 1894–96. http://dx.doi.org/10.1063/1.113002.

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29

Newton, M. I., G. McHale, F. Martin, E. Gizeli, and K. A. Melzak. "Pulse mode operation of Love wave devices for biosensing applications." Analyst 126, no. 12 (November 16, 2001): 2107–9. http://dx.doi.org/10.1039/b109259f.

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30

Gorbachev, K. V., E. V. Nesterov, V. A. Stroganov, and E. V. Chernykh. "A multi-pulse mode of operation of a magnetocumulative generator." Instruments and Experimental Techniques 55, no. 4 (July 2012): 465–68. http://dx.doi.org/10.1134/s0020441212030049.

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31

Burdakov, A. V., A. P. Avrorov, A. V. Arzhannikov, V. T. Astrelin, V. I. Batkin, A. D. Beklemishev, V. S. Burmasov, et al. "Development of Extended Heating Pulse Operation Mode at GOL-3." Fusion Science and Technology 63, no. 1T (May 2013): 29–34. http://dx.doi.org/10.13182/fst13-a16869.

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32

Illy, Stefan, Konstantinos A. Avramidis, Gerd Gantenbein, Zisis Ioannidis, Jianbo Jin, Parth C. Kalaria, Ioannis Gr Pagonakis, et al. "Recent Status and Future Prospects of Coaxial-Cavity Gyrotron Development at KIT." EPJ Web of Conferences 203 (2019): 04005. http://dx.doi.org/10.1051/epjconf/201920304005.

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Coaxial-cavity gyrotrons are microwave sources that can extend the possible power levels of hollow cavity gyrotrons significantly and make them attractive for future fusion experiments and power plants. KIT already demonstrated operation of a modular short-pulse 170 GHz coaxial-cavity gyrotron with an output power of 2.2 MW, operating in the TE34,19 mode. Today’s focus of KIT is the verification of this technology at longer pulses, which will prove the long-pulse capabilities also. At the moment, the current KIT prototype has been extended with cooling capabilities for all critical, highly loaded components of the tube and two new, different electron guns are available for operation. This paper will give an overview about the recent status and the future prospects connected to the coaxial-cavity gyrotron development at KIT, including both experimental and theoretical activities.

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33

Latiff, A. A., H. Shamsudin, Z. C. Tiu, H. Ahmad, and S. W. Harun. "Switchable soliton mode-locked and multi-wavelength operation in thulium-doped all-fiber ring laser." Journal of Nonlinear Optical Physics & Materials 25, no. 03 (September 2016): 1650034. http://dx.doi.org/10.1142/s021886351650034x.

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A switchable soliton mode-locked and multi-wavelength operation in thulium-doped fiber laser (TDFL) is demonstrated based on nonlinear polarization rotation (NPR) technique. The TDFL produces a soliton pulse operating at 1917.66[Formula: see text]nm using a 5[Formula: see text]m long thulium-doped fiber (TDF) as a gain medium as well as nonlinear medium. The solitonic behavior is further identified with two orders of Kelly sidebands in the output spectrum. The mode-locked emission is obtained from threshold pump power of 522–1052[Formula: see text]mW with consistent pulse repetition rate of 14.7[Formula: see text]MHz. Maximum pulse energy is calculated as 0.89[Formula: see text]nJ at pump power of 1052[Formula: see text]mW, whereas the maximum pulse width is estimated to be approximately 1.36[Formula: see text]ps corresponding to sech2 pulse profile. By shifting the polarization orientation, the cavity can change to multi-wavelength operation with signal-to-noise ratio (SNR) higher than 53[Formula: see text]dB. At pump power of 1037[Formula: see text]mW, three stable peak wavelengths are generated with a power fluctuation and constant spacing of [Formula: see text] dB and 7.4[Formula: see text]nm, respectively.

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34

Mead, James B., and Andrew L. Pazmany. "Quadratic Phase Coding for High Duty Cycle Radar Operation." Journal of Atmospheric and Oceanic Technology 36, no. 6 (June 2019): 957–69. http://dx.doi.org/10.1175/jtech-d-18-0108.1.

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AbstractQuadratically varying phase codes applied from pulse to pulse can be used to impart a range-dependent frequency shift in the decoded signal of a pulsed radar. Radars employing such codes can operate at extremely high pulse repetition frequencies (PRFs) with overlaid signals from multiple echo trips separated in the spectral domain. When operating at high PRFs, the radar duty cycle can approach 50% in a single-antenna system. High duty cycle operation results in a substantial increase in average transmit power with a proportional increase in signal processing gain as compared to a conventional pulsed radar. The shortest quadratic phase code, or base code, has a length equal to the number of echo trips M that can be unambiguously resolved in the spectral domain. The decoded waveform is essentially free from range sidelobes under ideal conditions. However, amplitude and phase errors associated with nonideal phase coding result in range sidelobes that appear at all echo trips in the decoded signal. These sidelobes can be suppressed by using a composite phase code composed of a periodically repeating base phase code added to a much longer quadratic code with a proportionally slower phase variation. Meteorological data gathered with a Ka-band radar operating at 3.0-MHz PRF at 45% duty cycle are presented. A comparison of these data with data gathered in short-pulse mode at a duty cycle of 0.3% exhibited a 21-dB improvement in the Doppler spectrum signal-to-noise ratio, equal to the ratio of the respective duty cycles.

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35

Arzhannikov, Boris Alexeevich, Alexander Petrovich Sukhoguzov, Andrey Nikolaevich Shtin, and Timofey Sergeevich Tarasovskiy. "Justification of power decrease of electric locomotive at three-phase system of electric traction when traction rectifier switches to open-phase mode." Transport of the Urals, no. 4 (2021): 100–106. http://dx.doi.org/10.20291/1815-9400-2021-4-100-106.

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The paper presents a short description of electric traction systems used on electrified railways in the world. For the proposed three-phase system of electric traction the authors consider features of operation of 6-pulse bridge rectifiers in full-phase and open-phase modes. The paper also demonstrates principal schemes and time diagrams that explain operation of 6-pulse bridge rectifiers in the open-phase mode at connection of valveside windings of a transformer «star» / «star» and «star» / «delta». On the basis of executed research the authors present relations that connect voltages, currents and power of 6-pulse bridge rectifiers in the open-phase mode for controlled and uncontrolled transformers.

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36

Petkovšek, Rok, Vid Agrež, Jaka Petelin, Luka Černe, Udo Bünting, and Boštjan Podobnik. "Pulses on Demand in Fibre and Hybrid Lasers." Strojniški vestnik – Journal of Mechanical Engineering 65, no. 11-12 (November 18, 2019): 680–89. http://dx.doi.org/10.5545/sv-jme.2019.6352.

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This paper presents an investigation of pulse-on-demand operation in fibre and hybrid lasers. Two methods for efficient gain control that enable the generation of laser pulses at arbitrary times with controlled pulse parameters are presented. The method of direct modulation of the pump power in the high-power laser oscillator is shown to generate pulses with a duration in the nanosecond range, with repetition rates varying during operation from a single shot to over 1 MHz. An advanced method using a combination of marker and idler seeding a fibre amplifier chain is investigated. Such a system can easily achieve repetition rates of several tens of MHz. The lasers’ performances were successfully tested in a real environment on an industrial platform for laser transfer printing. Similar concepts were used for a laser source with ultrashort laser pulses (femtosecond range) on demand by using a mode-locked seed as a source and a solid-state amplifier to achieve high pulse energy and peak power.

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37

Шашкин, И. С., А. Ю. Лешко, Д. Н. Николаев, В. В. Шамахов, Д. А. Веселов, Н. А. Рудова, К. В. Бахвалов та ін. "Одномодовые лазеры (1050 нм) мезаполосковой конструкции на основе гетероструктуры AlGaAs/GaAs со сверхузким волноводом". Физика и техника полупроводников 54, № 4 (2020): 414. http://dx.doi.org/10.21883/ftp.2020.04.49150.9334.

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The radiation properties of single-mode lasers based on an AlGaAs/GaAs heterostructure with an ultra-narrow waveguide are studied. It is shown that the use of an ultra-narrow waveguide (100 nm) and thin (70 nm) wide-gap barriers at the waveguide/cladding interface improves the vertical divergence. The lateral and vertical divergences were 5 and 18.5 degrees, respectively, for the developed narrow-stripe (5.1 µm) single-mode lasers. An efficient single-mode operation up to a power of 200 mW is demonstrated. A further increase in current leads to the onset of higher-order modes, while the maximum optical power achieved under continuous-wave (CW) operation is limited by overheating and is 550 mW. The transfer to a pulsed operation (pulse width 200 ns) made it possible to raise the maximum peak optical power to 1500 mW.

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38

Isakova, Yulia I., Galina E. Kholodnaya, and Alexander I. Pushkarev. "Influence of Cathode Diameter on the Operation of a Planar Diode with an Explosive Emission Cathode." Advances in High Energy Physics 2011 (2011): 1–14. http://dx.doi.org/10.1155/2011/649828.

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This paper presents the results of experimental investigations into the current-voltage characteristics of a planar diode with an explosive emission cathode made from graphite. Studies were performed using a TEU-500 pulsed electron accelerator (350–500 keV, 100 ns, 250 J per pulse). Duration of diode operation, in a mode when electron current is limited by the emissive ability of the graphite cathode, is 15–20 ns. The contribution of the cathode periphery to total electron current appears only as an increase in the emissive surface area due to an expansion of explosive plasma. Investigations of an ion diode with a graphite cathode (plane and focusing geometry) were also carried out. Experiments were performed using a TEMP-4M ion accelerator, which forms two nanosecond pulses: the first negative pulse (150–200 kV, 300–600 ns) followed by the second positive (250–300 kV, 150 ns). Total diode current in the first pulse is well described by the Child-Langmuir law for electron current at a constant rate of plasma expansion, equal to 1.3 cm/μs. It is shown that for an area of flat cathode over 25 cm2, the influence of edge contribution does not exceed measurement error of total diode electron current (10%).

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39

Nakano, Toshihiro, Michael Zeutzius, Hideo Miyanishi, Toshiaki Setoguchi, and Kenji Kaneko. "Studies on Pulse Jet Engine by Wind Tunnel Testing." International Journal of Rotating Machinery 7, no. 2 (2001): 79–85. http://dx.doi.org/10.1155/s1023621x01000070.

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Simple design and efficiency make pulse jet engines attractive for aeronautical short-term operation applications. An active control system extends the operating range and reduces the fuel consumption considerably so that this old technology might gain a new interest. The results on wind tunnel experiments have been reported together with the impact of combustion mode (pulse or steady) on system performance.

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40

Shang, Xinxin, Linguang Guo, Huanian Zhang, Dengwang Li, and Qingyang Yue. "Titanium Disulfide Based Saturable Absorber for Generating Passively Mode-Locked and Q-Switched Ultra-Fast Fiber Lasers." Nanomaterials 10, no. 10 (September 26, 2020): 1922. http://dx.doi.org/10.3390/nano10101922.

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In our work, passively mode-locked and Q-switched Er-doped fiber lasers (EDFLs) based on titanium disulfide (TiS2) as a saturable absorber (SA) were generated successfully. Stable mode-locked pulses centred at 1531.69 nm with the minimum pulse width of 2.36 ps were obtained. By reducing the length of the laser cavity and optimizing the cavity loss, Q-switched operation with a maximum pulse energy of 67.2 nJ and a minimum pulse duration of 2.34 µs was also obtained. Its repetition rate monotonically increased from 13.17 kHz to 48.45 kHz with about a 35 kHz tuning range. Our experiment results fully indicate that TiS2 exhibits excellent nonlinear absorption performance and significant potential in acting as ultra-fast photonics devices.

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41

Pushkarev, A. I., Y. I. Isakova, and I. P. Khaylov. "Improvement in the statistical operation of a Blumlein pulse forming line in bipolar pulse mode." Review of Scientific Instruments 85, no. 7 (July 2014): 073303. http://dx.doi.org/10.1063/1.4883177.

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42

Hertlein, M. P., A. Scholl, A. A. Cordones, J. H. Lee, K. Engelhorn, T. E. Glover, B. Barbrel, et al. "X-rays only when you want them: optimized pump–probe experiments using pseudo-single-bunch operation." Journal of Synchrotron Radiation 22, no. 3 (April 2, 2015): 729–35. http://dx.doi.org/10.1107/s1600577515001770.

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Laser pump–X-ray probe experiments require control over the X-ray pulse pattern and timing. Here, the first use of pseudo-single-bunch mode at the Advanced Light Source in picosecond time-resolved X-ray absorption experiments on solutions and solids is reported. In this mode the X-ray repetition rate is fully adjustable from single shot to 500 kHz, allowing it to be matched to typical laser excitation pulse rates. Suppressing undesired X-ray pulses considerably reduces detector noise and improves signal to noise in time-resolved experiments. In addition, dose-induced sample damage is considerably reduced, easing experimental setup and allowing the investigation of less robust samples. Single-shot X-ray exposures of a streak camera detector using a conventional non-gated charge-coupled device (CCD) camera are also demonstrated.

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43

Harun, S. W., B. M. Nawi, and A. A. Latiff. "Nickel oxide film saturable absorber for mode-locking operation at 1.55-micron region." Journal of Nonlinear Optical Physics & Materials 27, no. 02 (June 2018): 1850020. http://dx.doi.org/10.1142/s0218863518500200.

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The generation of mode-locking pulse train in Erbium-doped fiber laser (EDFL) cavity was demonstrated using Nickel Oxide (NiO) saturable absorber (SA). The NiO compound synthesized via sonochemical method was embedded into poly ethylene oxide (PEO) film through solution casting technique to fabricate the SA film device. A small piece of the SA film was sandwiched between two ferrules in the EDFL cavity. By adding 180[Formula: see text]m single mode fiber (SMF) in the ring cavity, a stable mode-locking pulse train operating at 1558[Formula: see text]nm with a repetition rate of 1.1[Formula: see text]MHz was achieved. At 197.5[Formula: see text]mW pump power, the proposed mode-locked EDFL has output power and pulse energy of 3.35[Formula: see text]mW and 3.36[Formula: see text]nJ, respectively. This study may well be the first demonstration of mode-locked EDFL using NiO-based SA. The result indicates that NiO is the promising material for ultrafast photonic applications.

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44

Василенко, Станислав Иванович, Максим Юрьевич Кудряшов, Александр Валерьевич Прокофьев, and Александр Анатольевич Решетников. "Features of measuring radial velocity in mixed location mode." Herald of Tver State University. Series: Applied Mathematics, no. 1 (April 28, 2022): 33–44. http://dx.doi.org/10.26456/vtpmk632.

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В работе исследуется смешанный режим работы РЛС, включающий циклическую генерацию и прием отраженных импульсных сигналов разной длительности на разной несущей частоте. В таком режиме по техническим причинам происходит потеря информации об отдельных принятых импульсах. Предложен алгоритм интерполяции значений сигнала в потерянных импульсах. Алгоритм включает в себя устранение неоднозначности определения радиальной скорости цели из-за потери информации. The paper investigates the mixed mode of operation of the radar, including cyclic generation and reception of reflected pulse signals different durations at different carrier frequencies. In this mode for technical reasons, there is a loss of information about the individual received pulses. An algorithm for interpolation of signal values in lost pulses is proposed.

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45

CHUDAKOV, Alexander I., Valery O. IVASHCHENKO, Alexey P. ZELENCHENKO, and Nikolay V. LYSOV. "Optimization of control systems for suburban trains." Proceedings of Petersburg Transport University 2021, no. 4 (December 2021): 499–506. http://dx.doi.org/10.20295/1815-588x-2021-4-499-506.

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Objective: The use of pulse conversion of electricity on direct-current traction rolling stock is discussed. Methods: A variant of the system for regulating the operating modes of traction motors of suburban electric trains using a pulse converter based on insulated gate bipolar transistors is described. (IGBT). Results: The proposed impulse control system is presented as a possible option for the modernization of the applied control systems, which makes it possible to improve the traction and energy indicators of suburban electric trains. The advantages of pulse converters based on IGBTs are shown in comparison with converters based on one- and two-operation thyristors. A simplifi ed electrical diagram of the power circuit of a motor car with a pulse converter is presented, a description of the operation of the power circuit in the traction mode and in the modes of rheostatic and regenerative braking is given. Practical importance: The presented results of the technical and economic comparison of the control systems of the ED4M electric train with a Современные технологии – транспорту 505 ISSN 1815-588Х. Известия ПГУПС 2021/4 contactor-rheostat control system and an electric train with regulation of the operating modes of traction electric motors by a pulse converter based on IGBT prove the best energy effi ciency of an electric train equipped with a pulse control system

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46

Sarathkumar, S., K. Periyannaswamy, and S. Thanigaiarasu. "Modelling of an Electromagnetic Space Propulsion System for Pulse Mode Operation." Procedia Engineering 38 (2012): 3691–99. http://dx.doi.org/10.1016/j.proeng.2012.06.424.

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47

Wan, Baonian, Jiangang Li, Houyang Guo, Yunfeng Liang, Guosheng Xu, Liang Wang, and Xianzu Gong. "Advances in H-mode physics for long-pulse operation on EAST." Nuclear Fusion 55, no. 10 (July 29, 2015): 104015. http://dx.doi.org/10.1088/0029-5515/55/10/104015.

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48

Read, Kendall, Florian Blonigen, Nicole Riccelli, Margaret Murnane, and Henry Kapteyn. "Low-threshold operation of an ultrashort-pulse mode-locked Ti:sapphire laser." Optics Letters 21, no. 7 (April 1, 1996): 489. http://dx.doi.org/10.1364/ol.21.000489.

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49

Jian Wu, 吴健, 蔡华 Hua Cai, 韩晓红 Xiaohong Han, and 曾和平 Heping Zeng. "Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser." Chinese Optics Letters 6, no. 1 (2008): 76–78. http://dx.doi.org/10.3788/col20080601.0076.

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50

Zhang, Jie, Ying Guo, Xiaojiang Huang, Jing Zhang, and Jianjun Shi. "Operation Mode on Pulse Modulation in Atmospheric Radio Frequency Glow Discharges." Plasma Science and Technology 18, no. 10 (September 27, 2016): 974–77. http://dx.doi.org/10.1088/1009-0630/18/10/02.

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