摘要
为了准确评估激光装置靶室内、外的周围剂量当量分布情况,进一步验证剂量评估模型的合理性,利用蒙特卡罗程序FLUKA对激光靶室进行了全建模,基于现有电子源项理论模型以及XG-Ⅲ激光装置典型实验条件对靶室内外剂量情况进行了计算分析。为了更准确地测量光子周围剂量当量,需要对光子剂量测量组件进行设计,对不同能量区间电子对测量元件的总剂量贡献进行了模拟分析,在此基础上针对0~15 MeV区间电子的屏蔽进行了优化设计,最后对光子剂量测量组件的效果进行了模拟计算,并进行了设计优化。模拟结果表明靶室内、外电子周围剂量当量均高于光子剂量当量。激光靶室主观察窗内、外的电子与光子剂量水平相差约1个量级。相较于无屏蔽情况下,优化后的测量组件使电子剂量水平下降了99.7%,光子剂量水平仅衰减了30.9%,电子与光子的剂量比值约为0.12,总光子剂量中有5%是高能电子在PMMA中发生轫致辐射所贡献。模拟结果表明:经过对测量结果的合理修正,该组件可适用于强激光装置中靶室内的光子剂量测量。
The possibility of using lasers to achieve previously unobtainable states of matter in the laboratory gained much attention following the demonstration of the first pulsed laser in 1960.In the following few years there was plenty research activity as attempts were made to increase the peak power and focused intensity in order to reach extreme conditions within the laboratory.Laser-acceleration technology is rapidly developing.Petawatt class lasers have been constructed for specific research activities,including particle acceleration,inertial confinement fusion and radiation therapy,and for secondary source generation(X rays,electrons,protons,neutrons and ions).As a new source of ionizing radiation,dose measurement in ultra-intense and ultra-short laser facilities is of great value for radiation protection of the environment,occupational staff and shielding design in laser device design stage.Owing to the pulsed and mixed characteristics of radiation field around the laser facility,it is really challenging to accurately measure the dose equivalent induced by bremsstrahlung photon in the target chamber of the laser facility.Moreover,the rationality of dose assessment model needs more experimental data and to be further verified.To reach this point,the Monte-Carlo program FLUKA was employed to characterize the radiation filed distribution.Firstly,a complete and thorough target chamber module was established according to the XG-Ⅲgeometry parameter and material composition.The in-chamber and out-chamber dose distribution were then calculated and analyzed based on the existing theoretical model of electron source term and typical experimental conditions.The electron energy distribution,characteristic electron temperature,scaling laws and laser-to-energy conversion efficiency were introduced.Secondly,the typical electron spectrum was divided into four intervals.The portion of different energy intervals to the total equivalent dose was determined.Thirdly,a bremsstrahlung photon dose equivalent measuring module was desi
作者
宋鸿鹄
闫永宏
衣宏昌
武祯
李君利
邱睿
SONG Honghu;YAN Yonghong;YI Hongchang;WU Zhen;LI Junli;QIU Rui(Department of Engineering Physics,Tsinghua University,Beijing 100084,China;Science and Technology on Plasma Physics Laboratory,Laser Fusion Research Center,China Academy of Engineering Physics,Mianyang 621900,China)
出处
《原子能科学技术》
EI
CAS
CSCD
北大核心
2023年第3期630-638,共9页
Atomic Energy Science and Technology
基金
国家自然科学基金(12175114,U2167209)
清华大学自主科研计划。
关键词
超短超强激光装置
X射线剂量
屏蔽优化
ultra-intense and ultra-short laser facility
X ray dose
shielding design optimization
