针孔法测量X光源焦斑尺寸

通过针孔成像法得到X光源强度空间分布图像，直接读取图像数据得到X光源的半高宽焦斑（FWHM）尺寸，对图像数据进行傅里叶变换得到调制传递函数，并计算得到X光源的等效焦斑尺寸（50%MTF）。应用针孔成像法测量多脉冲电子直线感应加速器产生的X光源焦斑尺寸，测量结果表明，加速器性能稳定。定义焦斑形状因子参数并用于描述X光源分布，结果表明，该加速器X光源分布在高斯分布和本涅特分布之间变化。

X-ray spot size measurement with pinhole

The high intense pulse electron beam emitted and accelerated by linear induction accelerator (LIA) is focused to heavy metal target to produce X-ray pulses via bremsstrahlung mechanism. The X-ray is applied to high energy flash radiography. The X-ray spot size is a critical parameter for LIA and the main factor which degrades resolution of the flash radiography. This paper describes a pinhole imaging system measuring the X-ray spot size. The full width at half maximum (FWHM) of the X-ray spot size can be obtained from the pinhole image data. The modulation transfer function (MTF) which is derived from the X-ray spot image by Fourier transform is applied to calculate the 50%MTF spot size. In the continuous experiments of multi-pulse electron linear induction accelerator (MPELIA), the X-ray spot size is measured and the results demonstrate reliable performance of MPELIA. The concept of form factor is introduced, and the measured results show that the MPLIA X-ray spot distribution changes between Gaussian and Bennett distribution.