Study Of Electron Beam Moir(?) Fringes And Spatial Resolution Of The Time Dilation X-ray Framing

Image converter tube is used to obtain pulse gated,photoelectric conversion and image enhancement in picoseconds framing camera,which is a high-speed diagnosis tool with high temporal resolution and 2-dimensional spatial resolution.It is a important tool which is used to study the nanosecond transient phenomenology,such as the symmetrical compress and instability of target in inertial confinement fusion(ICF),the planar spatial distributing of implosion image.Target is compressed to have dozens of micron and the process persist only 100 picoseconds,if one wants to obtain its information,the temporal resolution and spatial resolution of X-ray framing camera must be improved.Pulse-dilation framing camera is a new type framing camera reported in recent years,which is ultrahigh temporal resolution and imaged by magnetic lens.So the spatial resolution of the framing camera is limited by aberration and electron beam moiré fringes of the imaging system.Therefore the spatial and aberration characteristic of the imaging system and electron beam moiré fringes in the framing camera are studied.We wish to find a way to advance the spatial resolution and the work area of the camera.In this paper,the main completed research work has been shown below.1.The model of electron movement in the framing camera is established by using the numerical method.Study of the spatial and aberration characteristic of the electron optical imaging system by using geometrical aberration method.2.The trajectories of electron in converter tube are simulated and the relationship of the imaging range,spatial resolution and magnetic lens,off-axis range is researched.The variation of the spatial resolution is provided by simulated result.While dc bias on the PC is-3 k V and there is single magnetic lens with 16 cm numerical-aperture,the spatial resolution within 10 mm off-axis range is better than 3.5 lp/mm;While dc bias on the PC is-3 k V and there is single magnetic lens with 40 cm numerical-aperture,the spatial resolution within 10 mm off-axis range is better than 8 lp/mm;While dc bias on the PC is-3 k V and there is double magnetic lenses with 16 cm numerical-aperture,the spatial resolution within 10 mm off-axis range is better than 6.5 lp/mm;While dc bias on the PC is-3 k V and there is treble magnetic lenses with 16 cm numerical-aperture,the spatial resolution within 10 mm off-axis range is better than 10 lp/mm.3.The imaging principle of current-carrying solenoid is discussed.The spatial resolution of the camera with current-carrying solenoid is provided by simulated result.While dc bias on the PC is-3 k V and there is 2.275×106 A/m2 current density in the solenoid,the spatial resolution within 30 mm off-axis range is better than 6 lp/mm.The spatial resolution is stable as the off-axis range increasing.4.According the principle and simulated result,a framing camera is designed to research the spatial characteristics.While the imaging ratio is 2:1 and there is single magnetic lens,the measured static spatial resolution within 12 mm off-axis range is better than 5 lp/mm;Same imaging ratio and there is double magnetic lenses,the measured static spatial resolution within 24 mm off-axis range is better than 5 lp/mm;Same imaging ratio and there is treble magnetic lenses,the measured static spatial resolution within 30 mm off-axis range is better than 5 lp/mm.5.An image conversion tube with a magnetic lens was designed to observe electron beam moiré fringes.The experimental result is contrasted to optical moiré fringes theory.The changes to the fringe direction and the spacing as a function of the rotation angle between the photocathode and the anode mesh were examined.While the rotation angle more than 45° or less than 0°,the modulation of the electron beam moiré fringes is less than 5%.The principle is help to avoid spatial resolution reduce what are caused by electron beam moiré fringes.The main innovations are:1.Introduce a framing camera with multiple lenses to correct for aberration.The work area of the camera is increased fourfold.2.The electron beam moiré fringes in an image converter tube are observed.The changes to the fringe as a function of the rotation angle between the photocathode and the anode mesh were examined.The principle of the electron beam moiré fringes are compare with optical moiré fringes theory.Research of electron beam moiré fringes is help to decrease the modulation of the fringes on the electron image.