In this paper, a special high-voltage pulse synchronization system is designed for the framing camera used in the Z-pinch experiment.The system adopts a system architecture that combines a programmable delay module and a high-voltage pulse generation module. The delay module uses a digital delay chip to achieve picosecond delay. The high-voltage pulse generation module uses a Marx pulse circuit combined in series and parallel to generate high-voltage narrow pulse.Technical parameters: pulse amplitude 2.5kv, pulse width 4.03ns, delay range 2s, delay accuracy 500Ps, pulse jitter less than 150ps. It avoids the line loss and waveform distortion caused by the long transmission line of the traditional delay line method, improves the system integration, reduces the volume and weight of the equipment, and is more convenient to deploy and use.
In order to improve the dynamic range and the signal-noise ratio of the image intensifier, keep the flux of the screen of image intensifier constant. In the article, introduced a design of the switching power supply and tested its performance. Firstly, used a sampling amplifier amplify the feedback current signals. The feedback signals were converted into square wave signals through a digital circuit. Then, using the MOSFET in the post stage circuit produced high voltage and high speed adjustable square pulses. The frequency of the pulse is 1 kHz, the speed of the cutting edge is 20ns and the amplitude is 200V. The photoelectron emission time of the photocathode is short when the width of the high speed pulse is narrow for strong illumination. On the contrary, the time is long when the width is wide for weak illumination. The number of photoelectron is a constant no matter what kind of the illumination. It keeps the flux reaching the phosphor screen constant.
Delay line anode detector has high spatial resolution and high count rate. It has been an important technical means for
single photon imaging from near earth space to deep space. A two dimensional delay line anode is designed using
multilayer circuit board technology. A complete set of PCB delay line anode single photon detection system is established.
The spatial resolution of the detector is theoretically analyzed. Moreover, the signal transmission characteristic of PCB
delay line and the dark count rate of the detector are tested. Theoretical analysis and experimental results show that the
detector spatial resolution is about 100um and the overall dark count rate is 4counts/cm2 at 2.3KV.
KEYWORDS: Device simulation, Spatial resolution, Cameras, Microchannel plates, Electrodes, Monte Carlo methods, Modulation transfer functions, Scattering, Laser scattering, Electron beams
The structural models of micro-channel plate (MCP) and fluorescent screen of the framing camera were established. By
combining the finite element integration and Monte Carlo method, software Simion and Lorenz were respectively used to
simulate the effects of different voltages loaded on the fluorescent screen, different closed distance between fluorescent
screen and MCP, and electrode immersion depth at MCP output on the spatial resolution, in order to obtain an
axisymmetric distribution curve. Results showed that the closed distance between MCP and fluorescent screen had the
largest impact on the framing camera’s spatial resolution. In addition, higher fluorescent screen voltage did not
necessarily result in better spatial resolution, as it was influenced by the light-emitting mechanism of the fluorescent
screen. At the framing camera’s current closed distance of 0.8mm, a fluorescent screen voltage of 5000V could achieve
the best spatial resolution.
Ultrafast phenomenon has presented widely in natural phenomenon and scientific and technological research. Therefore, study on ultrafast phenomenon is of great important in many research and technology fields. In recent years, the development and application of ultra-short laser pulse has been covered many areas. It has been developed into a powerful tool used to research ultrafast phenomena. In the implementation process of the ultra-short laser pulses, high-speed switching plays a vital role. The difficulty of high-speed switching design is to make the ultrafast electric pulse load on the both ends of the crystal with minimum distortion and delay. It is very difficult to switch electro-optic crystal at a high frequency in traditional method. In this paper, a new method is designed, which combined the electro-optic crystal and micro-strip line. The crystal is a part of the transmission path and the signal path of the micro-strip line is broadened or narrowed continuously to make the impedance matching to 50 ohm. The good match between pulse signal and the crystal make sure the high frequency switches of the crystal. The amplitude loss is less than 11%, and the delay is less than 1 nanosecond.
The design of nanosecond high-voltage ultra wide band bipolar pulse generator is shown in this paper. By analyzing the principle of the avalanche diode and doing the research of the related circuit acting on the pulse, this generator can generate a nanosecond high-voltage ultra wide band bipolar pulse, which its peak-to-peak voltage is about 400V and the pulse time width is 2ns. The experimental results showed a good agreement with the simulation results. A negative unipolar high-voltage pulse, having a fast falling-edge and a slowly exponential rising-edge, was firstly generated by the MARX circuit consist of the avalanche diodes. Then the use of the high speed avalanche diode could generate a negative unipolar high-voltage narrow Gaussian pulse, having a fast falling-edge and a fast rising-edge. In an attempt to cancel the reflection of the pulse made by the impedance mismatch, the circuit introduced the capacitor(C) and inductor(L) by calculating. Eventually a nanosecond high-voltage ultra wide band bipolar pulse could be got after going through the differentiator consist of introducing the right resistance, capacitance and inductance by calculation and experiment, and a filter with 2GHz bandwidth makes the bipolar smooth and perfect.
A new method to get a X-ray framing camera with picoseconds time resolution was proposed based on time amplification. Its principle comes from that we use high voltage electrical pulse to get speed dispersion of the photoelectrons pulse first, and then the photoelectrons pulse will be stretched in axial direction by drift area, at the end the photoelectrons pulse after stretched will be framing imaged by a traditional MCP(microchannel plate)gated framing camera. A model of the camera was built according to this method. Time amplification of the system is about 30, and image magnification of the system is about 0.4. Parameters for designing the camera system were presented after theoretical deriving and model simulation. At last, theoretical time resolution and spatial resolution of the camera were given.
Imaging systems with high temporal resolution are needed to study rapid physical phenomena ranging from shock waves, including extracorporeal shock waves used for surgery, to diagnostics of laser fusion and fuel injection in internal combustion engines. However, conventional streak cameras use a vacuum tube making thus fragile, cumbersome and expensive. Here we report an CMOS streak camera project consists in reproducing completely this streak camera functionality with a single CMOS chip. By changing the mode of charge transfer of CMOS image sensor, fast photoelectric diagnostics of single point with linear CMOS and high-speed line scanning with array CMOS sensor can be achieved respectively. A fast photoelectric diagnostics system has been designed and fabricated to investigate the feasibility of this method. Finally, the dynamic operation of the sensors is exposed. Measurements show a sample time of 500 ps and a time resolution better than 2 ns.
Based on the principle of capacitor pre-charging, an analog pulse stretch circuit is designed for detecting peak power of narrow laser impulse. Experimental test were carried out. And it could achieve regulation accuracy of 5ps, jitter<600ps. Due to the need of different delay ranges during the practical applications, the analog pulse stretch circuit is optimized. It doesn’t only meet the different adjustment ranges, but also maintains high regulation accuracy.
We present evidence that transmission loss in gated x-ray framing cameras can affect relative gains. Transmission loss is caused by a variety of factors including: incident voltage waveform, matched load, width of Au electrode gap, and so on. The transition electrode in MCP (Micro-channel Plate) is continuous gradual change line, and it has good capability of compensation. When continuous gradual change micro-strip line is designed, dielectric loss tangent is one of transmission loss factors too. The model structure is designed based on the analysis of modeling and simulation techniques and experiment data as well as forecast target. The transmission loss is reduced from 50% to 25%, the transmission efficiency is greatly improved.
Framing camera based on gated Micro-channel plate (MCP) was widely used in inertial confinement fusion (ICF) and Z-pinch because of its ultrafast time-resolve. Electrons with imaging information are multiplied when the HV pulse propagating through the MCP strip line. Obviously, the HV pulse was used as a shutter here, then the exposure time of the imagine will be determined by the width of the pulse. Theoretical analysis indicates that thegating pulse(200ps) has a bandwidth of 5GHz, thus, impedance match in the propagating path of the pulse will be very important. Impedance mismatch will cause reflecting of the pulse and decrease the transmission efficiency. This will cause un-uniformity of the dynamic gain of the MCP, and finally resulting in imagedistortion. A new designed impedance matching circuit is developed in this paper. Simulated results showedthatthe newdesignedimpedance matching circuit couldreduce the reflection of thegating pulse significantly, and dynamicgain uniformity of the MCP was increased simultaneously
A novel method to realize fast photoelectric diagnostics using ordinary CCD is presented. By changing the mode of charge
transfer of CCD, fast photoelectric diagnostics of single point with linear CCD and high-speed line scanning with array CCD can
be achieved respectively. A fast photoelectric diagnostics system of single point based on linear CCD has been designed and
fabricated to investigate the feasibility of this method. A pulsed blue light emitting diode (LED) has been used to measure the
system. As a proof of concept, the rate of photoelectric diagnostics of single point reachs up to 20 MHz. The results demonstrated
that the method of fast photoelectric diagnostics based on ordinary CCD is feasible.
Here we report an ultrafast x-ray imaging sensor based on optical measurement of the effects of x-ray absorption and
electron hole pair creation in a direct band-gap semiconductor. Our results indicate that this technology can be used to
provide a new approach for x-ray detectors and x-ray imaging systems with picosecond temporal resolution at x-ray
energies ~10 keV. The x-ray absorption in GaAs produces a transient, non-equilibrium, electron-hole pair distribution
which is then sensed by the phase modulation of the optical probe beam. The basic physics of the detector,
implementation considerations, and preliminary experimental data are presented and discussed. Through further
development, this x-ray imaging sensor could provide insight into previously unmeasurable phenomena in many fields.
KEYWORDS: Field programmable gate arrays, Signal processing, CMOS sensors, Camera shutters, Data storage, Data acquisition, Control systems, Cameras, Charge-coupled devices, Image sensors
The detection of high-speed dynamic spectrum is the main method to acquire transient information. In order to obtain the
large amount spectral data in real-time during the process of detonation, a CMOS-based system with high-speed
spectrum data acquisition is designed. The hardware platform of the system is based on FPGA, and the unique
characteristic of CMOS image sensors in the rolling shutter model is used simultaneously. Using FPGA as the master
control chip of the system, not only provides the time sequence for CIS, but also controls the storage and transmission of
the spectral data. In the experiment of spectral data acquisition, the acquired information is transmitted to the host
computer through the CameraLink bus. The dynamic spectral curve is obtained after the subsequent processing. The
experimental results demonstrate that this system is feasible in the acquisition and storage of high-speed dynamic
spectrum information during the process of detonation.
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