高能闪光照相对电子束参数的要求

Beam Parameter Requrements for Radiography

对高能闪光机光源性能用Monte-Carlo方法模拟研究发现:并非击靶电子束半径越小、发射度越低,闪光机的照相性能就会越好．研究结果表明:为了使闪光照相图像视面上照射量分布比较均匀,对束半径与电子束归一发射度有一个联合限制,对于20MeV闪光机,如果击靶电子束有效半径是 0．12cm,那么仅当束归一发射度≥550cm·mrad时,在2°内的照射量不均匀性才小于5％．

With the Monte Carlo method, the performance of X-ray source of a flash X-ray radiographic machine is simulated. It is not true that the smaller the beam radius and the emittance, the better the performance of radiographic image. The results indicate that there is a joint restriction on the beam radius and the beam emittance. If the beam radius on the target is 0.12cm and the exposure inhomogeneity within the azimuthal angle of 2° is not lager than five percentage, the normalized emittance of the beam should not be less than 550cm·mrad.