A Shutter Strobe Circuit Used For Image Converter Tube, Double-Proximity Focused Image Intensifier And Photomultiplier With Microchannel Plate

Field: Physics and Astronomy (Physical Sciences)

This paper mainly deals with the present status of the development of nanosecond image converter framing cameras and nanosecond double-proximity image intensifier framing cameras in our country, and discusses shutter pulse generator circuits of these cameras. 1-2 The mixing circuit consisting of avalanche transistor series and pulse thyratron maintains strong anti-interference. Its trigger delay time is 14ns, the trigger jitter is about :500 ps, the shortest output pulse width is 15ns, its amplitude is 550V and the pulse spacing is 150ns. The circuit consisting of avalanche transistor series and rapid restorer diode has 300v of output pulse amplitude, lOns of pulse width and 5Ons of pulse spacing. It is suitable for a new type of image converter tube which is not strict with pulse waveform. But, the strobe circuit of multichannel double-proximity image intensifier camera can provides 2ns of pulse width, 2ns of pulse spacing and -300V of amplitude. When it is used with double-proximity tube, this kind of strobe circuit can obtain a dynamic resolution of better than 4.71p/mm. When it is used for MCP-PMT ns pulse generator, its largest synchronous pulse frequency is 30 kc; pulse width is 4-40ns; adjustable amplitude is 200-300. These circuits can be used for controlling low-light silicon target pick-up tubes, for testing high voltage electric device characteristics, for ns pulse source and laser modulation by improving them slightly. The existing ns image converter framing cameras are limited in their applications, since their framing rates can not be high enough to satisfy the requirements for measuring tran-sient phenomena. In 1982, we developed a ns ring-shaped grating image converter framing camera with an exposure time of 15ns and a frame spacing of 150ns. The reason why these data indexes are not high enough is that the ring-shaped grating image converter tube is very strict with the front and back edges and the flat-topped oscillation of the shutter strobe pulse waveform added to the control-grating of the ring-shaped grating image converter tube. The time of switching devices selected as gate pulses can not be very short. The switching devices are in a state of big current pulse discharging, the restoring time of the tube is longer from leading to stopping, so it is difficult for several gate pulses to form rather short spacing and steep-front and back serial pulses on the same common load. Thus, the dynamic space resolution of the image converter tube does not meet the applied requirements because of the poor gate pulse waveform. The gate pulse generator switching device in this kind of framing camera adopts a mixing circuit consisting of the avalanche transistor series and the pulse thyratron (Fig. 1). The output pulse amplitude of this circuit is 550V, rising edge: 2.5ns, falling edge: 4.5ns, trigger delay: 14ns, jitter: 500ps. It adopts low impedance matched output. As the circuit has advantages of short trigger delay, little jitter and strong anti-electromagnetic interference ability, the satisfied results have been obtained in the test of once-through strong electromagnetic interference.