四路并联二极管辐射X射线场参数计算

摘要

The electron energy distribution of diode was calculated using current and voltage .Moreover ,the characteristics of X‐ray spectrum in parallel diodes environment were calculated using Monte Carlo simulation model .The dose distribution of X‐ray of four parallel diodes environment was calculated using numerical integral method .In the model ,the small cells ,which were divided by diodes ,were used as radiation source . The results indicate that the X‐ray fluence in the position from the target 5 cm is 3.55 mJ/cm2 .The energy of photons with less than 120 keV in the X‐ray spectrum is less than 81.84% of the total energy .The average photon energy of the X‐ray spectrum is 62.18 keV ,and the diode electron beams conversion efficiency is 0.30% .In the area of 2 700 cm2 ,the dose uniformities of axial and diagonal orientation are 3.20 and 6.31 separately ,and in the area of 2 000 cm2 ,the values are less than 2 .%利用二极管的电压、电流计算了发射电子束能谱参数，建立了四路并联二极管阳极靶蒙特卡罗粒子输运计算模型，给出了辐射X射线场参数；将四路并联二极管的每个二极管划分为若干小单元，将其作为点源，采用数值积分的方法计算了辐射X射线剂量分布，并分析了空间不同位置处每路二极管对剂量的贡献。结果表明：真空中，距离四路并联二极管阳极靶5 cm位置处，X射线注量为3.55 mJ／cm2，光子平均能量为62.18 keV ，120 keV以下的光子占辐射X射线谱总能量的81.84％，电子束转换效率为0.30％；在2700 cm2范围内，中轴线和对角线上的剂量均匀性分别为3.20和6.31；在2000 cm2范围内，中轴线和对角线上的剂量均匀性均小于2。