12MeV强流脉冲电子束对钽靶的破坏研究  

Destruction Study of Tantalum Target Impacted by 12MeV Electron Beam

作　　者：龙继东[1] 林郁正[1] 罗飞[2] 谷卓伟[2] 石金水[2] 

机构地区：[1]清华大学工程物理系,北京100084 [2]中国工程物理研究院,绵阳621900

出　　处：《高能物理与核物理》2004年第5期564-568,共5页High Energy Physics and Nuclear Physics

基　　金：国防科技基础研究项目资助~~

摘　　要：强流高能电子束由于具有很强穿透能力 ,在材料内的能量沉积具有体分布特点 ,因此其对材料的辐照破坏体现出和低能电子以及X光等不同的特点 .本文分析了金相显微镜和扫描电镜下的被 12MeV的强流电子束轰击后的 1.2mm厚度钽靶的破坏点形貌 ,其破坏断面体现为力学韧性撕裂 ,且关于靶中心基本对称 .为了解释这种现象 ,文中用蒙特卡罗的数值模拟方法给出了电子束在钽靶内的沉积能量分布 :能量沉积呈现靶中心吸能高 ,两侧低 ,且关于中心基本对称的特点 .针对破坏断面特点和靶的吸热情况 ,我们给出高能电子束对靶材破坏初步的定性解释 :认为高能电子束的强穿透能力使得靶材各部分几乎同时加热 .靶材在极短时间里吸收大量能量 ,发生剧烈膨胀 .由于能量沉积特点 ,中心部分材料膨胀最厉害 ,受到两侧边界的强烈约束 ,将产生两大小相近的热激波相对传播 .激波在两侧自由界面反射 ,产生向内传播稀疏波 .当两个稀疏波在靶中心区域相遇 ,就造成了靶对称撕裂的破坏形态 .The radiation destructive appeatance caused by intensive electron beam current with 12MeV energy reveals different mechanism of fracture from those caused by lower energy electron or X-ray due to the strong penetrating ability of the electron. In the paper, the fracture profiles of the 1.2mm Ta target, which is destructed by 12MeV electron beam, are studied using microscope and scanning electron microscope. The result indicates mechanical tear is the major reason, and moreover, the tear fracture is almost symmetrical. In order to understand this, the energy deposit of electron beam along the depth of the target is given out by Monte-Carlo simulation, which is also symmetrical and higher in center, lower in sides. A preliminary conclusion on the major destructing mechanism of the target is drawn out: 12MeV electron beam, which has strong penetration ability, can heat the whole target almost at the same time. The expansion of the center part of the target is constrained by the boundary which results in two shock waves with most destructive power produced in the two sides of center. After the shock waves reach the free surfaces of the target, by wave reflection, two rarefaction waves will propagate inward, then symmetric tearing happens when the two waves meet at the center region of the target.

关 键 词：电子束 轫致辐射靶 热激波 稀疏波 蒙特卡罗法 

分 类 号：O572.2[理学—粒子物理与原子核物理]