模具表面改性日益受到人们重视。本文采用二维Particle-in-cell/Monte Carlo Collision模型对等离子体浸没离子注入处理凹模型腔内表面的鞘层动力学及均匀性进行了研究。考察了电压脉宽对鞘层中电势分布、离子的运动状态以及型腔内表面...模具表面改性日益受到人们重视。本文采用二维Particle-in-cell/Monte Carlo Collision模型对等离子体浸没离子注入处理凹模型腔内表面的鞘层动力学及均匀性进行了研究。考察了电压脉宽对鞘层中电势分布、离子的运动状态以及型腔内表面离子注入剂量、能量和角度的空间分布的影响。结果表明随着电压脉宽的增加,凹模型腔内表面的注入剂量不均匀性增加,同时注入到内表面的高能离子数目也增加。脉冲宽度变化对注入角度影响不大,离子以接近垂直的入射角度注入到型腔底部,而在侧壁上离子注入角度接近45°。当脉冲宽度较大时,发现少部分注入到侧壁上的离子以一定角度从下往上注入到样品表面,这是由于碰撞效应造成的。从能量和剂量的角度,存在一个合适的脉冲宽度,过大的脉宽会引起剂量不均匀性增加,同时离子注入能量也会下降。展开更多
This paper presents a novel approach to seek the bar width for ripple filter used in pencil beam scanning proton therapy.A weight decay quadratic programming method is employed for the new optimization strategy.Compar...This paper presents a novel approach to seek the bar width for ripple filter used in pencil beam scanning proton therapy.A weight decay quadratic programming method is employed for the new optimization strategy.Compared to the commonly used iterative-least-square technique,the ripple filter derived by the proposed method not only has better depth dose uniformity,i.e.,the dose uniformity is within 0.5%,but also has triangle-like vertical cross-sectional shape which is suitable for manufacture.Moreover,the new method has such good robust characteristics that it is also applicable to the real application with unavoidable measurement errors and noises.The simulation results of this study may be helpful in improving the design of the ripple filter.展开更多
文摘模具表面改性日益受到人们重视。本文采用二维Particle-in-cell/Monte Carlo Collision模型对等离子体浸没离子注入处理凹模型腔内表面的鞘层动力学及均匀性进行了研究。考察了电压脉宽对鞘层中电势分布、离子的运动状态以及型腔内表面离子注入剂量、能量和角度的空间分布的影响。结果表明随着电压脉宽的增加,凹模型腔内表面的注入剂量不均匀性增加,同时注入到内表面的高能离子数目也增加。脉冲宽度变化对注入角度影响不大,离子以接近垂直的入射角度注入到型腔底部,而在侧壁上离子注入角度接近45°。当脉冲宽度较大时,发现少部分注入到侧壁上的离子以一定角度从下往上注入到样品表面,这是由于碰撞效应造成的。从能量和剂量的角度,存在一个合适的脉冲宽度,过大的脉宽会引起剂量不均匀性增加,同时离子注入能量也会下降。
文摘This paper presents a novel approach to seek the bar width for ripple filter used in pencil beam scanning proton therapy.A weight decay quadratic programming method is employed for the new optimization strategy.Compared to the commonly used iterative-least-square technique,the ripple filter derived by the proposed method not only has better depth dose uniformity,i.e.,the dose uniformity is within 0.5%,but also has triangle-like vertical cross-sectional shape which is suitable for manufacture.Moreover,the new method has such good robust characteristics that it is also applicable to the real application with unavoidable measurement errors and noises.The simulation results of this study may be helpful in improving the design of the ripple filter.
