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Showing papers on "Rise time published in 2020"


Journal ArticleDOI
TL;DR: In this paper, a self-powered and fast response photodetectors based on β-Ga2O3/4H-SiC pn heterojunction are demonstrated by depositing β-O3 films on p-type 4H−SiC templates using Pulse Laser Deposition method, and the detectors exhibit an ultrahigh current Ion/Ioff ratio more than 103 (∼1655) at the light intensity of 91 μW/cm2 and a fast photo-response speed (a rise time of 11 milliseconds and a decay time of 19 milliseconds

93 citations


Journal ArticleDOI
TL;DR: In this article, a single step chemically synthesized dumbbell-shaped ZnO microcrystal has been utilized to fabricate UV photodetectors and highly selective H2 gas sensors.

31 citations


Journal ArticleDOI
TL;DR: The design of antenna with optimized geometry and satisfied parameters to detect PD for impulsive voltage is reported and the influence of both impulse voltage parameters and test configuration on PD features are discussed.
Abstract: The partial discharge (PD) in inverter-fed motors generated from high frequency and short rise time impulsive voltage are more complex than traditional sinusoidal voltage operated motors due to the noise initiated from fast switching power electronics devices. Available PD sensors and related technology for DC and sinusoidal voltage cannot be used at repetitive impulsive voltage conditions. This work aims to report the design of antenna with optimized geometry and satisfied parameters to detect PD for impulsive voltage. The antenna is verified and the influence of both impulse voltage parameters and test configuration on PD features are discussed. The envelope detection technique after the filter in the frequency domain was proposed to reduce the complexity and cost of PD test hardware under impulsive voltages with fast rise times. The frequency domain energy of PD from motor insulation is mainly distributed in the range of 0.6-1.8 GHz. By increasing the amplitude and frequency of input impulsive voltage, the range of PD energy spectrum is enlarged to (1.5-1.8 GHz) and by decreasing input amplitude the PD signal strength decays abruptly. Moreover, the high-frequency distribution of PD energy attenuates more severely with the distance and the electromagnetic energy of PD decays nonlinearly with the increase of propagation distance. Therefore, under the premise of satisfying the safety test, selecting the test distance below 15 cm can ensure that the test results have a high signal-to-noise ratio and signal integrity. The experience reported in this study could provide suggestions for off-line PD measurements for inverter-fed motor insulation evaluations for manufacturers.

30 citations


Journal ArticleDOI
20 Apr 2020
TL;DR: In this article, Zn-diffusion and oxide-relief apertures are used to manipulate the optical modes and reduce the parasitic capacitance, respectively, in a unit device for a 940 nm VCSEL array.
Abstract: High-power vertical-cavity surface-emitting laser (VCSEL) arrays, which can serve as the light source in modern lidar and three-dimensional optical sensing systems, have recently attracted a lot of attention. In these types of systems, the time-of-flight (ToF) technique, based on the round-trip time of short optical pulses is usually adopted. Further enhancement of the ranging distance and depth resolution in these ToF driven systems by the incorporation of a VCSEL array with a high available power, high brightness (narrow divergence angle), and fast response time is highly desirable. However, a large number of light emission apertures (several hundreds) in the VCSEL array is usually necessary to raise the output power level to several watts. This leads to a large parasitic capacitance and the RC-limited bandwidth may become the dominant limiting factor of the speed of the high-power VCSEL array. In this work, Zn-diffusion and oxide-relief apertures are used to manipulate the optical modes and reduce the parasitic capacitance, respectively, in a unit device for a 940 nm VCSEL array. The demonstrated VCSEL array has a quasi-single-mode output, high available power (4 W; 1% duty cycle), narrow divergence angle (${\sim}{14}^\circ $∼14∘ at ${{1/e}^2}$1/e2) under maximum output power, and a fast rise time ($ {\lt} {100}\;{\rm ps}$<100ps). These results open up new possibilities for further enhancing the performance of ToF sensing systems at the 940 nm wavelength.

30 citations


Journal ArticleDOI
TL;DR: In this paper, a photonic crystal structure based on nonlinear cavities has been proposed to improve the time response of a 2-to-4 decoder, which includes an array of chalcogenide rods with an air gap in which the spatial period of rods is 500 nm.
Abstract: In this paper, a photonic crystal structure based on nonlinear cavities has been proposed to improve the time response of a 2-to-4 decoder. The structure includes an array of chalcogenide rods with an air gap in which the spatial period of rods is 500 nm. The radius of the fundamental rods is assumed to be 125 nm, which results in a photonic bandgap of 1092–1724 nm at TM mode. Three cavities, including the nonlinear rods with a Kerr coefficient of 10−14m2/W, drop the incoming waves concerning the amount of optical intensity. The finite-difference time-domain method was used to calculate the components of the electric and magnetic fields throughout the structure. The time analysis of the device shows the rise time is equal to 200 fs, which is less than one for the previous structures. The area of 110µm2 and the margins of 4% and 88% for logics 0 and 1 are other advantages of the proposed structure. Based on the obtained results, it was proven that the performance of the 2-to-4 photonic crystal-based decoder has been improved by this work.

27 citations


Journal ArticleDOI
TL;DR: In this article, an all-optical analog-to-digital converter using photonic crystal nonlinear ring resonators was proposed. But the main goal of this work was to design an optical analog to digital converter with no upper limit for the input optical intensity when generating "11" codes at the output ports.
Abstract: Optical analog to digital conversion is very important for implementing all-optical data processing systems. In this study, we designed an all-optical analog to digital converter using photonic crystal nonlinear ring resonators. The main goal of this study was to design an optical analog to digital converter with no upper limit for the input optical intensity when generating “11” codes at the output ports. Simulation results showed that the maximum rise time for the proposed structure is about 1.5 ps

27 citations


Journal ArticleDOI
Jianguo Wang1, Shoupeng Wang1, Li Cai1, Dai Lu1, Quanxin Li1, Mi Zhou1, Yadong Fan1 
TL;DR: In this paper, the induced voltage waveforms exhibit three components including a slow increase preceding the initial negative peak, following a rapid polarity reversal and the attenuated oscillations, and the test results show that the negative peak value of the induced voltages at the terminal of distribution generated by nearby negative triggered lightning generally exceeds the positive peak value.
Abstract: This paper presents the induced voltage measured at the terminal of a 10 kV distribution line when triggered lightning taking place at a distance of 40 m. It is shown that the induced voltage waveforms exhibit three components including a slow increase preceding the initial negative peak, following a rapid polarity reversal and the attenuated oscillations. The waveform parameters are defined in this paper. The observed negative peak value ranges from −47.1 kV to −7.5 kV. The positive peak value ranges from 5.3 kV to 20.9 kV, and the peak to peak value ranges from 12.8 kV to 63.2 kV. The test results show that the negative peak value of the induced voltage at the terminal of distribution generated by nearby negative triggered lightning generally exceeds the positive peak value, and in some cases the negative peak value even reaches twice the positive peak value. The negative 10%-90% rise time ranges from 2.3 μs to 88.5 μs, and the average oscillation period is about 18 μs. Both negative and positive peaks of induced voltages show good linear relationship with the peaks of lightning return stroke current.

25 citations



Journal ArticleDOI
TL;DR: In this article, Fe doping is shown to significantly improve X-ray detection performance of Ga2O3, consolidating its applicability as a next-generation Xray detector functioning with low power, high SNR and linearity.
Abstract: (010) EFG-grown Fe-doped β-Ga2O3 was tested as a low-noise X-ray detector with Ti/Au electrodes vertical structure. Its performance at low, high and no applied voltages was examined. The fabricated detector showed high X-ray detection performance manifested in its signal’s short fall and rise time ( 103). Moreover, the X-ray-induced current signal exhibits high stability. Sub-band UV photocurrent signal showed a significantly slower response compared to X-ray-induced conductivity signal. Possible charge transport mechanisms involving ion migration are suggested and discussed. In this study, Fe doping is shown to significantly improve X-ray detection performance of Ga2O3, consolidating the applicability of Ga2O3 as a next-generation X-ray detector functioning with low power, high SNR and linearity, and significantly improved transient characteristics.

23 citations


Journal ArticleDOI
TL;DR: In this paper, an RF MEMS switch is modeled on a thin bridge which is micromachined and suspended on a layer of dielectric, and a pull-in voltage is applied to the switch.

22 citations


Journal ArticleDOI
TL;DR: Simulation results using a 65-nm CMOS technology confirm the potentialities of the proposed strategy and show a reduction of the rise time and the input energy higher than 20% as compared with the traditional topology.
Abstract: This brief proposes a simple but effective strategy to improve wake-up operation in energy-autonomous systems which exploits Charge Pump (CP) circuits to boost voltage directly from energy harvester generators. By means of few auxiliary diodes and parasitic junctions, the CP is managed to retain the charges in the pumping capacitors when the harvesting power source is not able to feed the system, thereby reducing the rise time and input energy demand during the start-up phase. Simulation results using a 65-nm CMOS technology confirm the potentialities of the proposed strategy and show a reduction of the rise time and the input energy higher than 20% as compared with the traditional topology.

Journal ArticleDOI
Saikang Shen1, Jiaqi Yan1, Yanan Wang1, Guoxiang Sun1, Weidong Ding1 
TL;DR: A repetitive nanosecond pulse generator is developed based on the optimized parameters, which can produce pulses with an amplitude of 9.04 kV, a rise time of 3.4 ns, a pulse width of 18.8 ns, and a maximum repetition rate of 1 kHz.
Abstract: Avalanche transistor-based Marx bank circuit (MBC) is widely used to generate nanosecond pulses with high amplitude, high repetition rate, fast rise time, and low jitter. Recently, the problem that avalanche transistors in the first several stages of $M \times N$ -stage MBC fail frequently has been alleviated by adopting auxiliary triggering topology (ATT). However, the reasons for improvement and the optimal design method have not been fully understood. In this article, a flexible $4\,\,\times10$ -stage MBC is developed to further investigate the output characteristics under different modified stages, capacitors, and loads through both experiments and simulations. The results show that on the one hand, adopting ATT will cause energy loss of the main capacitors to auxiliary triggering capacitors, which can decrease the output voltage; and on the other hand, transistors operating in the auxiliary triggering switching-ON mode have lower residual voltage than in the lower overvoltage switching-ON mode, which can increase the output voltage. This implies that there exists an optimal value of modified stages, which is 5 for the $4\,\,\times10$ -stage MBC. Besides, by adopting ATT, the waveform of output pulse changes, and the rising edge becomes faster. Finally, a repetitive nanosecond pulse generator is developed based on the optimized parameters, which can produce pulses with an amplitude of 9.04 kV, a rise time of 3.4 ns, a pulse width of 18.8 ns, and a maximum repetition rate of 1 kHz at the 75- $\Omega $ open-ended cable. Also, the feasibility of this modified MBC is validated by the preliminary experiments of driving atmospheric pressure plasma jet (APPJ).

Journal ArticleDOI
TL;DR: An enhancement of power-synchronization control is proposed, whereby pole–zero cancellation in the closed-loop system is achieved, whereby step-response ringing and overshoot are eliminated.
Abstract: In this letter, an enhancement of power-synchronization control is proposed, whereby pole–zero cancellation in the closed-loop system is achieved. An effect thereof is that step-response ringing and overshoot are eliminated. For strong grids, the closed-loop bandwidth increases, allowing a shorter step-response rise time.

Journal ArticleDOI
22 May 2020-Sensors
TL;DR: A novel intelligent double closed-loop control with chaotic optimization and adaptive fuzzy logic is developed for a multi-sensor based variable spray system, where a Bang-Bang relay controller is used to speed up the system operation, and Adaptive fuzzy nonlinear PID is employed to improve the accuracy and stability of the system.
Abstract: During the variable spray process, the micro-flow control is often held back by such problems as low initial sensitivity, large inertia, large hysteresis, nonlinearity as well as the inevitable difficulties in controlling the size of the variable spray droplets. In this paper, a novel intelligent double closed-loop control with chaotic optimization and adaptive fuzzy logic is developed for a multi-sensor based variable spray system, where a Bang-Bang relay controller is used to speed up the system operation, and adaptive fuzzy nonlinear PID is employed to improve the accuracy and stability of the system. With the chaotic optimization of controller parameters, the system is globally optimized in the whole solution space. By applying the proposed double closed-loop control, the variable pressure control system includes the pressure system as the inner closed-loop and the spray volume system as the outer closed-loop. Thus, the maximum amount of spray droplets deposited on the plant surface may be achieved with the minimum medicine usage for plants. Multiple sensors (for example: three pressure sensors and two flow rate sensors) are employed to measure the system states. Simulation results show that the chaotic optimized controller has a rise time of 0.9 s, along with an adjustment time of 1.5 s and a maximum overshoot of 2.67% (in comparison using PID, the rise time is 2.2 s, the adjustment time is 5 s, and the maximum overshoot is 6.0%). The optimized controller parameters are programmed into the hardware to control the established variable spray system. The experimental results show that the optimal spray pressure of the spray system is approximately 0.3 MPa, and the flow rate is approximately 0.08 m3/h. The effective droplet rate is 89.4%, in comparison to 81.3% using the conventional PID control. The proposed chaotically optimized composite controller significantly improved the dynamic performance of the control system, and satisfactory control results are achieved.

Journal ArticleDOI
TL;DR: Modification of objective function by adding performance parameter into consideration could improve the performance of rise time, settling time, overshoot percentage, and steady state error.
Abstract: PID Optimization by Genetic Algorithm or any intelligent optimization method is widely being used recently. The main issue is to select a suitable objective function based on error criteria. Original error criteria that is widely being used such as ITAE, ISE, ITSE and IAE is insufficient in enhancing some of the performance parameter. Parameter such as settling time, rise time, percentage of overshoot, and steady state error is included in the objective function. Weightage is added into these parameters based on users’ performance requirement. Based on the results, modified error criteria show improvement in all performance parameter after being modified. All of the error criteria produce 0% overshoot, 29.51%-39.44% shorter rise time, 21.11%-42.98% better settling time, 10% to 53.76% reduction in steady state error. The performance of modified objective function in minimizing the error signal is reduced. It can be concluded that modification of objective function by adding performance parameter into consideration could improve the performance of rise time, settling time, overshoot percentage, and steady state error

Journal ArticleDOI
20 Feb 2020-Energies
TL;DR: In this paper, a thermal deformation compensation model is presented that can reduce the influence of spindle thermal error on machining accuracy, which is one of the main reasons for the loss of accuracy in lathe machining.
Abstract: Thermal error is one of the main reasons for the loss of accuracy in lathe machining. In this study, a thermal deformation compensation model is presented that can reduce the influence of spindle thermal error on machining accuracy. The method used involves the collection of temperature data from the front and rear spindle bearings by means of embedded sensors in the bearing housings. Room temperature data were also collected as well as the thermal elongation of the main shaft. The data were used in a linear regression model to establish a robust model with strong predictive capability. Three methods were used: (1) Comsol was used for finite element analysis and the results were compared with actual measured temperatures. (2) This method involved the adjustment of the parameters of the linear regression model using the indicators of the coefficient of determination, root mean square error, mean square error, and mean absolute error, to find the best parameters for a spindle thermal displacement model. (3) The third method used system recognition to determine similarity to actual data by dividing the model into rise time and stable time. The rise time was controlled to explore the accuracy of prediction of the model at different intervals. The experimental results show that the actual measured temperatures were very close to those obtained in the Comsol analysis. The traditional model calculates prediction error values within single intervals, and so the model was divided to give rise time and stable time. The experimental results showed two error intervals, 19µm in the rise time and 15µm in the stable time, and these findings allowed the machining accuracy to be enhanced.

Journal ArticleDOI
TL;DR: In this paper, a coaxial three-gap demountable multigap multiaperture pseudospark switch (MGMA-PSS) is presented, which has three gaps which are separated by two cavity drift space regions.
Abstract: In this article, the development and switching characterization of a coaxial three-gap demountable multigap multiaperture pseudospark switch (MGMA-PSS) prototype is presented. The investigated MGMA-PSS geometry has three gaps which are separated by two cavity drift space regions. A high dielectric constant ferroelectric-based single plasma trigger unit, located within the hollow cathode of the first gap, is used for effective discharge initiation and subsequent synchronous breakdown of the three gaps of the MGMA-PSS. To guarantee long lifetime with high currents and high hold-off voltages and optimized plasma coupling, kidney-shaped ring slot electrodes with baffles are used. Each of the gaps is designed for a minimum voltage hold-off up to 30 kV, with a total voltage hold-off for the MGMA-PSS of approximately 70 kV. Studies of switching behavior are carried out at different operating conditions, such as operating voltages (5–40 kV), hydrogen gas pressures (10–40 Pa), various trigger configurations, and change of circuit parameters [charging capacitance (36, 200, and 380 nF), load resistance (2.7 and $8.3~\Omega $ )]. The short time-scale analysis of the breakdown voltage waveform shows steps in the voltage fall at low gas pressure (< 20 Pa) and low hold-off voltages (< 15 kV), which indicates a too-long time delay in plasma formation and coupling within the drift regions. This effect could not be observed at higher voltages (≥15 kV) and gas pressure (≥20 Pa). The overall performance of the three-gap prototype PSS has been analyzed in terms of hold-off voltage, fall time, current rise time, peak current, delay time, and related parameters.

Journal ArticleDOI
TL;DR: A novel closed-loop switched-capacitor capacitance-to-frequency converter (CFC) is presented in this article, capable of measuring from either a single-element or a differential capacitive sensor, providing ratio and ratiometric outputs, respectively.
Abstract: A novel closed-loop switched-capacitor (SC) capacitance-to-frequency converter (CFC) is presented in this article. The proposed CFC is capable of measuring from either a single-element or a differential capacitive sensor (DCS), providing ratio and ratiometric outputs, respectively. Most of the existing autobalancing schemes for capacitive sensors use the closed-loop approach but require precise sinusoidal ac excitation and provide an analog output that is sensitive to parasitic capacitances. Also, the use of voltage-controlled resistors (VCRs) in many of these schemes limits the linearity and accuracy of their output. The SC-CFC presented in this article employs a simple dc reference for excitation and gives a digital output that is insensitive to parasitic capacitances, by virtue of design. Additionally, the output is linear, irrespective of the sensor characteristic, and independent of the nominal value of the sensor. This feature, along with its compatibility with single-element and DCSs, facilitates its ease of integration with a wide range of capacitive sensors. The CFC has a one-time correction mechanism that significantly reduces the impact of component mismatch. The prototype of the proposed scheme exhibits a maximum nonlinearity error (NLE) of 0.24%, a resolution of 12.59 effective number of bits (ENOB), and a rise time of 6 ms. In addition, the proffered design is fit for integrated circuit (IC) fabrication as it employs an SC approach.

Proceedings ArticleDOI
11 Oct 2020
TL;DR: In this paper, a series of tests are conducted on electrical stators representative of typical low voltage machines used in traction and industrial applications to quantify the detrimental effects on machine insulation lifetime.
Abstract: SiC power devices are gaining increased interest due to their superior performance and increased efficiency in motor drives compared to traditional Si-based IGBT converters. However, the increased switching frequency and much faster switching transients (high dv/dt) of Silicon Carbide (SiC) compared to their IGBT counterparts, can result in increased stress in electrical machines. To quantify these detrimental effects on machine insulation lifetime, a series of tests are conducted on electrical stators representative of typical low voltage machines used in traction and industrial applications. A Design of Experiment (DoE) methodology is employed to identify the test sequence using three stressors. In particular, three values of DC link voltage level, rise time or slew rate of the voltage waveform, and switching frequency, respectively are considered. The paper describes the planned tests and conditions, the insulation health monitoring method employed, and preliminary results.

Journal ArticleDOI
TL;DR: In this paper, the advantages of employing multilevel PWM waveforms with adjustable rise times operating above partial discharge inception are discussed in order to reduce the life length of high voltage motors.
Abstract: Decreasing the rise time of pulse width modulated waveforms (PWM) has been observed to reduce the life length of high voltage motors. To solve this problem, the advantages of employing multilevel PWM waveforms with adjustable rise times operating above partial discharge inception are discussed in this paper. Examples of how the voltage supply circuits can be designed to enable investigation of this well as measured results are presented. To elucidate this approach, it is investigated what influence the choice of inverter levels has on the partial discharge (PD) characteristics within motor winding material applying adjustable rise times. The test objects were fed from either three- or four level inverter voltage waveforms to resemble realistic stress conditions as in field application. Presented experimental results show that the total peak and summed PD magnitude (exposure) drops considerably when applying a longer rise time at the critical voltage flanks and is shown to reduce the wear of the winding insulation material, showing the consistency between PD pattern and wear. It is further suggested that the presence of PDs can be eliminated by adjusting the rise times at the most critical voltage flanks and thus enhance the life of the machine winding. The presented principles can be implemented for various PWM pattern.

Journal ArticleDOI
TL;DR: In this paper, a low voltage sub-nanosecond monolithic pulsed current driver for light detection and ranging (LIDAR) applications is presented. But the performance of the driver is limited by its high-resolution pico-seconds (ps) range pulse width and rapid rise and fall times.
Abstract: This article introduces a new low voltage sub-nanosecond monolithic pulsed current driver for light detection and ranging (LIDAR) applications. A unique architecture based on a controlled current source and Vernier activation sequence, combined with a monolithic implementation, allows operation from low input voltage levels, high-resolution pico-seconds (ps) range pulse width, and rapid rise and fall times. An on-chip low voltage pulsed driver sub-nanosecond prototype has been implemented in a TS 0.18- $\mu \text{m}$ 5-V-gated power management process. It incorporates an integrated wide range senseFET-based current sensor and a rail-to-rail comparator for current regulation. A separate line of investigation has been carried out to characterize the avalanche capabilities of the integrated lateral MOSFET power devices required for the driver IC. Several lateral diffused MOS (LDMOS) power devices have been custom designed and experimentally evaluated for life-cycle performance characterization. In addition, a delay-line (DL) based controller to govern the pulsed current driver IC is described and implemented on a field-programmable gate array (FPGA). To validate the concepts of the high-resolution LIDAR current driver, both discrete and IC experimental setups have been constructed and evaluated, validating the method for currents up to 20-A peak in discrete and 5 A in an integrated solution. Postlayout analysis and the experimental evaluation of the driver IC have been found to be in very good agreement. The experimental results demonstrate overall improvement on several operation properties, such as rise time, fall time, and pulse width resolution, of over one order of magnitude, compared to the state-of-the-art silicon-based LIDAR drivers. For 5-V input, and a representative output pulse of 5 A, the results that have been obtained are 900-ps rise time and fall time of 2.5 ns, all measured at the driver’s light output. In addition, the pulse width resolution has been enhanced to hundreds of ps, which is significantly below the intrinsic delay of the power switches.

Journal ArticleDOI
14 Jul 2020-Entropy
TL;DR: This paper discusses the implementation and tuning algorithms of a variable-, fractional-order Proportional–Integral–Derivative (PID) controller based on Grünwald–Letnikov difference definition and uses three different error values.
Abstract: In this paper, we discuss the implementation and tuning algorithms of a variable-, fractional-order Proportional-Integral-Derivative (PID) controller based on Grunwald-Letnikov difference definition. All simulations are executed for the third-order plant with a delay. The results of a unit step response for all described implementations are presented in a graphical and tabular form. As the qualitative criteria, we use three different error values, which are the following: a summation of squared error (SSE), a summation of squared time weighted error (SSTE) and a summation of squared time-squared weighted error (SST2E). Besides three types of error values, obtained results are additionally evaluated on the basis of an overshoot and a rise time of the output signals achieved by systems with the designed controllers.

Journal ArticleDOI
TL;DR: An on-demand current source module: the bang–bang transient performance enhancer (BBTPE), which is to follow fast variations in input signals with reduced overshoot and settling time without deteriorating the steady-state performance of the buck regulator.
Abstract: This article presents an agile supply modulator with optimal transient performance that includes improvement in rise time, overshoot and settling time for the envelope tracking supply in linear power amplifiers. For this purpose, we propose an on-demand current source module: the bang–bang transient performance enhancer (BBTPE). Its objective is to follow fast variations in input signals with reduced overshoot and settling time without deteriorating the steady-state performance of the buck regulator. The proposed approach enables fast system response through the BBTPE and an accurate steady-state output response through a low switching ripple and power efficient dynamic buck regulator. Fast output response with the help of the added module induces a slower rise of inductor current in the buck converter that further helps the proposed system to reduce both overshoot and settling time. This article also introduces an efficient selective tracking of envelope signal for linear PAs. To demonstrate the feasibility of the proposed solution, extensive simulations and experimental results from a discrete system are reported. The proposed supply modulator shows 80% improvement in rise time along with 60% reduction in both overshoot and settling time compared to the conventional dynamic buck regulator-based solution. Experimental results using the LTE 16-QAM 5 MHz standard shows improvement of 7.68 dB and 65.1% in adjacent channel power ratio (ACPR) and error vector magnitude (EVM), respectively.

Journal ArticleDOI
TL;DR: In this article, the performance of a single crystal diamond radiation detector with gold films on hydrogen-terminated diamond as electrical contacts and oxygen-termed diamond as surface isolation between electrodes was reported.
Abstract: We report the performance of a single crystal diamond radiation detector with gold films on hydrogen-terminated diamond as electrical contacts and oxygen-terminated diamond as surface isolation between electrodes. The origin-symmetric current-voltage characteristics showed excellent Ohmic contact behavior. An extremely low dark current value of 7.46 × 10−13 A/mm2 was measured at an electric field of 1 V/μm. The charge collection efficiency and energy resolution of this detector were 99.01% and 1.5% for holes, and 98.6% and 1.7% for electrons under irradiation with 241Am α-particles. Under 60Co γ-ray irradiation with a dose rate of 1.271 Gy/s, the gain factor, specific sensitivities, and signal-to-noise ratio were 49.46, 12.43 μC/Gy·mm3, and 1 × 106 at 200 V bias voltage (0.66 V/μm), respectively. A rise time of 347.4 ps of the response to a pico-second pulsed electron source was also measured. This research provides a possibility to improve the performance of the diamond radiation detector through diamond surface modification.

Journal ArticleDOI
TL;DR: In this paper, a shock-induced pulsed power switch based on electroexplosion of exploding bridge wire (EBW) was developed, and the electrical field distribution and electrothermal coupling of EBW were simulated using COMSOL multiphysics software to assess the rationality of structural parameters.
Abstract: The pulsed power switch plays an important role in a wide variety of pulsed power applications, such as plasma science and high-pressure-impact studies. This article develops a shock-induced pulsed power switch based on electroexplosion of exploding bridge wire (EBW). The electrical field distribution and electrothermal coupling of EBW are simulated using COMSOL Multiphysics software to assess the rationality of structural parameters. Employing microelectromechanical system technology, the switches are mass-produced with only three steps, improving experimental efficiency and lowering the cost. Electrical tests are conducted at a series of operation voltages varying from 600 to 1800 V, and the results indicated that peak current increases linearly with operation voltage, while delay time and rise time all show a slowly declined trend. A potential conduction mechanism is discussed for better understanding, and switch resistance is described mathematically. Finally, microchip exploding foil initiators are used as a test vehicle to verify the capability of the switch, and ultrafine hexanitrostilbene (HNS-IV) pellets are successfully detonated at 0.15 μ F/1300 V after the switch is closed.

Journal ArticleDOI
01 Dec 2020
TL;DR: In this paper, the surface discharge current pulses of polyetheretherketone (PEEK) material under positive repetitive square voltage in a nitrogen atmosphere were measured, and the influences of different voltage amplitudes and frequencies on the detail parameters of forward discharge and backward discharge current was statistically analyzed.
Abstract: In this study, the surface discharge current pulses of polyetheretherketone (PEEK) material under positive repetitive square voltage in a nitrogen atmosphere are measured. The influences of different voltage amplitudes and frequencies on the detail parameters of forward discharge and backward discharge current pulses are statistically analysed. The results show that as the square voltage amplitude increases, the current pulse amplitude, fall time and pulse width of both forward and backward discharge current increase, and the rise time does not change significantly. As the voltage frequency increases, current pulse amplitude, fall time and pulse width of both forward and backward discharge current decrease, and the rise time does not change significantly. Due to the independence of the discharge at different repetitive cycles, the specific discharge process in one cycle is analysed in detail to explain the influence mechanism of the voltage amplitude and frequency on the discharge current. By mean of the Richardson–Schottky and the Cavallini relaxation model, the relationship between discharge voltage ratio and surface charge, and the decay process of surface discharge are analysed. Furthermore, the influences of amplitude and frequency of the positive repetitive square voltage on the PEEK surface current pulses are explained qualitatively.

Journal ArticleDOI
TL;DR: The adaptation gains improve transient response of DC-DC Boost Converter several operating conditions and has a stable response and able to reach the model reference smoothly.
Abstract: Almost all electronic components require a DC power supply at present days. The needs of DC power supplies from low voltage scales, medium voltages such as generators, to high voltage scales for high voltage electricity transmission. The improvement of PI controller performances is presented in this paper. The adaptation gains improve transient response of DC-DC Boost Converter several operating conditions. Massachusetts Institute of Technology (MIT) rule is applied as an adaptive mechanism to determine the optimal control parameters in some conditions. The used adaptive control technique is Direct Model Reference Adaptive Control (MRAC), this method as able to control system in some various input voltage. The proposed method has a stable response and able to reach the model reference smoothly. However, the response of the system has instantaneously overshoot and follows the response back of model reference. The responses of proposed controller have short period of rise time, settling time, and overshoot.

Journal ArticleDOI
TL;DR: In this paper, a multiple reflection and multiple-path (MRMP) short-wavelength pass filter is manufactured to suppress the contribution from the slow component in the BaF2 crystal.
Abstract: BaF2 crystal is well known for its short fluorescent decay time for its fast component. In measuring the time profile of $\gamma $ -ray flux density, it is important to suppress the contribution from the slow component in the BaF2 crystal. A multiple reflection and multiple-path (MRMP) short-wavelength pass filter is manufactured to achieve this goal, which can filter the slow component by wavelength selection. To accurately investigate the time profile of the fast component in the BaF2 crystal, $\gamma $ -ray source is used. The experimental results show that this filter reduces the slow scintillation light emitted from the BaF2 crystal by 99.7% with a detection efficiency of $\approx 0.11$ electrons/ $\gamma $ for the fast component. The rise time, full-width at half-maximum (FWHM), and duration time for the fast component in a BaF2 detector are 0.31, 1.12, and 2.92 ns, respectively. The fast fluorescent component of the BaF2 crystal is short enough for subnanosecond pulse radiation detection.

Journal ArticleDOI
TL;DR: In this paper, modifications in the conventional structure of a ten-stage CMG were presented to generate various voltage profiles through variations in the stray capacitances between spark gaps and the body.
Abstract: Compact Marx generators (CMGs) are commonly used to provide high-power and high-voltage pulses. Generally, CMGs are composed of spark gaps, charging capacitors, resistors, connections, and a metal body. The stray capacitances between spark gaps and the body could play a significant role in the performance of these generators. This article presents modifications in the conventional structure of a ten-stage CMG to generate various voltage profiles through variations in stray capacitances. These capacitances have been calculated numerically for six reconfigured structures with COMSOL. Eventually, the modified CMGs have been simulated in MATLAB to statistically investigate the impacts of various modified structures on the features of the output voltage such as the voltage peak, the pulsewidth, and the rise time in comparison with the conventional structure. In light of the presented results, the proper and applicable structure would be utilized based on the type of the load.

Journal ArticleDOI
TL;DR: In this paper, a multichannel charge-sensitive preamplifier for silicon or germanium detectors is presented, which includes four channels optimized for anodic signals and one channel specifically designed for cathodic signals.
Abstract: The circuit structure and the experimental performance of a newly integrated multichannel charge-sensitive preamplifier for silicon or germanium detectors are shown. The circuit has been conceived and optimized for the silicon detector GAL-TRACE, employed for light and heavy ion spectroscopy in nuclear physics experiments. The chip includes four channels optimized for anodic signals and one channel specifically designed for cathodic signals. An I2C interface is used to adjust, as needed, a host of key parameters of the preamplifier, such as sensitivity and bandwidth. An integrated range booster yields an exceptional dynamic range of 103 dB for the cathodic channel. The circuit features a low power consumption of 11 mW per channel, a fast rise time of the order of 10 ns, and low noise. Thanks to an accurate design of the input stage, the equivalent noise charge, measured with a commercial shaping amplifier, is as low as 130 rms electrons at a shaping time of 6 $\mu \text{s}$ with 5 pF of detector capacitance. The bandwidth of the preampifier is adequate for pulse shape analysis techniques used for particle discrimination.