Study On Gain Character Of Gated Framing Camera

Presently ,framing camera is one of the important diagnosable instruments in high energy density experiments such as ICF,laser plasma. But it still has a lot of problems. The gain nonuniformity is the important one which causes serious distortion of the imaging results. So it is a significant job to research on the reasons of gain nonuniformity for the X-ray imaging diagnosing of high energy density physical experiments.The structure and working principle of framing camera is presented in the second chapter. The character of framing camera gain is researched. The gain model of Micro-channel-plate is established. The effects of framing camera parameters on the gain are analyzed. Results show that the voltage and electric field of micro channel are the main factors affecting the gain.The CST(Computer Simulation Technology)EM studio and CST microwave studio software are used to simulate the distribution of microstrip MCP electric field intensity on the condition of static voltage in the third chapter. The transmission character of gauss pulse voltage is simulated too. The static gain nonuniformity and dynamic gain nonuniformity are analyzed. The edge gain of microstrip is bigger on the condition of static voltage and the gain nonuniformity is clear. The gain has an exponential attenuation relationship with distance along the microstrip on the condition of dynamic voltage. The attenuation has a direct proportion with dielectric conductance.The static gain character,dynamic gain character and exposing time of framing camera are measured in the fourth chapter. Static gain distribution has a good consistency with CST simulation. The gain of microstrip edge is bigger. The dynamic gain distribution is consistent with CST simulation. The gain has an exponential attenuation relationship with distance along the microstrip and increases suddenly at the end of the microstrip. Gain attenuation is caused by the voltage attenuation. The increase of gain at the end is caused by end voltage reflection. According the experiment data analyzed, the gain attenuation coefficient is 0.3Np/cm, the voltage attenuation coefficient is 0.043Np/cm, the end reflection coefficient of voltage is 10% and the exposing time is 100ps±10%.Optimizing the gain uniformity of framing camera is researched in the fifth chapter. Three ways are used to compensate the gain nonuniformity which are static voltage compensation,end reflection of voltage and taper microstrip of MCP. The three ways are analyzed quantitatively. The physical model of optimizing the gain uniformity is established. The effects of three ways on optimizing gain uniformity are simulated. It turns out that the three ways have their own advantages and disadvantages. Static voltage compensation and taper microstrip are better. End reflection of voltage is difficult to control. It has a better effect that the three ways cooperate to optimize the gain uniformity than a single way is used individually.