无氧铜表面处理在束流准直器中的应用

Application of oxygen-free copper surface treatment in beam collimator

束流准直器作为加速器的关键部件,用于吸收不在预定轨道的束晕粒子。因良好的电导率和良好的准直效率,铜被广泛应用于准直器中作为挡块材料。通常,挡块位于超高真空环境中,承受高功率束流载荷冲击,其不同表面处理工艺直接影响传热性能及放气率。为评估无氧铜表面处理工艺对相关性能的影响,分别对其进行表面化学腐蚀发黑处理、高温氧化处理以及仅机械加工处理,结果表明:无氧铜表面发黑处理后,其热辐射系数明显增加,同时也伴随着放气率的明显增加;而通过高温氧化处理后的铜块,其表面热辐射系数与仅机械加工后的铜块差异不大,放气率有一定程度的增加。以散裂中子源二期项目中的动量准直器为研究对象,在一定的束流载荷作用下,挡块选用发黑无氧铜,可将其最高温度控制在125℃以下,同时增加两台离子泵可使该准直器所在区域真空度满足运行要求。

As a key component of accelerators,beam collimators are used to absorb the beam halo particles that are not in the predetermined orbit.Due to its good conductivity and collimation efficiency,copper is widely used in beam collimators as the absorber material.In general,absorbers are located in ultra-high vacuum environment,and also loaded with high beam power,different surface treatment processes of the absorber will directly affect its heat transfer performance and vacuum performance.To evaluate the effect of the surface treatment of oxygen-free copper,the surface chemical corrosion blackening treatment,high temperature oxidation treatment and mechanical processing treatment are carried out respectively.The test results show that the thermal radiation coefficient and outgassing rate of copper blocks are increased obviously with surface blackening,however,the surface heat radiation coefficient of the copper blocks after high temperature oxidation is close to that of the machined copper block,while the outgassing rate increases a little.Taking the CSNS-II momentum collimator as the research object,with the beam load,blackening oxygen-free copper is used as the absorber,the maximum temperature can be controlled below 125℃,and the pressure of the collimator can meet the operation requirements by adding two ion pumps.