【作者】 黄维；

【导师】 赵红卫； 叶民友；

【作者基本信息】 中国科学技术大学 ， 核科学与技术， 2017， 硕士

【摘要】 自上世纪的80年代末,ECR离子源为核物理及重离子加速器等领域做出了突出的贡献,此后世界各地的科学家们纷纷开展了对ECR离子源的研究。ECR离子源得到不断发展,其种类从早期的第一代离子源装置演变到如今以超导离子源技术为代表的第三代装置,其所能产生的离子类型也已从早期的几种气体如氮气、氧气等的中低电荷态离子,到现在从H到U的所有金属或非金属原子的高电荷态离子。大部分金属元素在自然界中处于固态,需要将其气态化才能进入ECR离子源中产生对应的元素离子,且气态化的金属原子(或簇团)数量需达到一定值。当前,在ECR离子源中产生这些在常温常压下只以固态形式存在的元素气态主要有以下几种方法:炉子加热法、直接等离子体加热法、等离子体溅射法、激光熔融技术以及挥发性化合物金属离子(MIVOC,Metallic ion from volatile compound)法等,其中炉子加热法具有束流强度高、稳定性好的特点。炉子加热法按其工作温区主要分为低温炉、高温炉,其中高温炉主要针对熔点1500 ℃以上的金属元素如钴、钛、钒、铂、铀等的强流离子束产生。本论文课题设计一种目标工作在1800～2000 ℃的高温金属炉,通过ANSYS仿真模拟分析了直流加热电阻炉中钽坩埚的温度分布及其在ECR离子源工作环境的强磁场中所受的洛伦兹力,并对坩埚高温下所受热应力进行模拟分析。根据模拟分析结果研制了直流加热电阻炉的结构,并对其进行了离线测试,实验中钽坩埚在1800 ℃以上发生的形变与ANSYS模拟结果相符,根据模拟分析给出了改进方案。改进后的电阻式加热高温炉能在1500 ℃时稳定维持48小时以上,而在1846 ℃时稳定维持6小时以上。对直流加热电阻炉进行了在线测试,得到了 25 eμA的Ni19+以及185 eμA的Pb28+,验证所设计的高温炉能在ECR离子源强磁场的环境中工作,同时针对出现的问题分析了影响高温炉稳定运行的因素。与此同时,研制了高频加热感应炉及电子束加热蒸发炉,并对两者进行了离线测试,结果表明两者均能使坩埚温度达到1800℃以上。对电子束加热蒸发炉进行了在线测试,结果表明电子束加热蒸发炉受ECR离子源弧腔内强磁场洛伦兹力的作用而无法正常工作,有待改进。更多还原

【Abstract】 Since the end of 1980s,a number of ECR ion sources with variable design have been successfully built in many countries and regions successively,as a result of their outstanding performance in the application of heavy ion accelerator technology and experiments of nuclear physics.The type of ion source has been evolved from the traditional 1st generation to the latest 3rd generation complex with superconducting technology.The ion beam species have also been enhanced from only few low and medium charge state gaseous ions to high charge state ions up to uranium.At room temperature,most of metals are solid.They have to be converted into gases in order to meet the needs of production of these metallic ion beams in an ECR ion source.The typical methods to produce metallic ion beams in ECR ion source are micro-oven,plasma heating,sputtering,laser ablation and MIVOC(Metallic Ion from Volatile Compounds),and so on,amongst which the micro-oven is so far the most reliable method in the production of intense high charge metallic ion beams.There are mainly two types of micro-oven in use,i.e.high and low temperature oven.High temperature oven is especially used for metals with melting temperature over 1500 ℃,such as cobalt,titanium,vanadium,platinum,uranium dioxide.In this thesis,I designed and tested an oven aiming to achieve a temperature as high as 1800～2000 ℃ for the application with an ECR ion source in refractory metallic ion beam production.This study uses ANSYS to simulate and analyze the temperature distribution on a tantalum crucible of high temperature oven and its Lawrence force under the strong magnet field in an ECR ion source.The thermal stress at high temperature has also been estimated with the simulation code.According to the test,the deformation of tantalum crucible over 1800 ℃ during the off-line test is consistent with the ANSYS simulation results,which puts forward an improved scheme.And the improved resistor heating micro-oven can remain stable at 1500 ℃ for 48 hours and 1846 ℃ for more than 6 hours in the off-line test.We test metals such as Nickel and Lead in the on-line test and get 25 eμA of Ni19+and 185 eμA of Pb28+.This results show that the resistor heating oven can work in the magnet field of ECR ion source.Then analyze the problem of resistor heating micro-oven according to the test.At the mean time,design inducting heating oven and electron beam heating oven.The results of off-line tests show that they can both achieve more than 1800 ℃.The on-line test of electron beam heating oven shows that it can’t work as usual because of the Lorentz force in the ECR ion source.It’ll be modified in the near future.更多还原