叠靶研究

 直线感应加速器（LIA）产生的高能、强流电子束与轫致辐射靶作用能够产生具有高剂量、小焦斑的X光，但伴随产生的回流离子会导致电子束束斑变大与X光分辨率降低，在多脉冲情况下更会影响到后续电子束的束靶作用等。叠靶结构能够增大束靶作用的立体空间，降低在靶面的能量沉积，可有效抑制回流离子的产生。对叠靶结构模型进行了理论计算与实验研究，并与单靶情况相比较，证实了在两种靶结构下所得到的X光照射量大小与角分布基本相同，但对于叠靶情况下靶面没有出现烧蚀现象，从而从根本上抑制了由靶面产生回流离子而对束流产生的过聚焦效应。

Development of distributed target

Linear introduction accelerator is expected to generate small diameter X ray spots with high intensity. The interaction of the electron beam with plasmas generated at the X ray converter will make the spot on target increase with time and debase the X ray dose and the imaging resolving power. A distributed target is developed which has about 24 pieces of thin 0.05mm tantalum films distributed over 1cm. Due to the structure adoption, the distributed target material over a large volume decreases the energy deposition per unit volume and hence reduces the temperature of target surface, then reduces the initial plasma formalizing and its expansion velocity. In this paper, the comparison and analysis with two kinds of target structures are presented using numerical calculation and experiments, the results show the X ray dose and normalized angle distribution of the two is basically the same, while the surface of the distributed target is not destroyed like the previous block target.